/* ===================================================
   Module Page Styles — Blockchain Course
   mehditmimi.com
   Shared layout for all blockchain module pages.
   Teaching mode CSS is included at the bottom.
   =================================================== */

/* Global scroll behaviour — ensures anchor jumps clear the sticky header */
html {
    scroll-behavior: smooth;
    scroll-padding-top: calc(var(--navbar-h) + 50px); /* navbar + breadcrumb bar + buffer */
}

/* ── Color palette: Bitcoin dark/orange theme ──────── */
:root {
    /* Actual measured navbar height: 60px logo + 1rem top padding + 1rem bottom padding = 92px */
    --navbar-h: 92px;
    --bg-primary:    #0a0c10;
    --bg-secondary:  #10131a;
    --bg-tertiary:   #181c26;
    --bg-card:       rgba(16, 19, 26, 0.88);
    --bg-card-hover: rgba(24, 28, 38, 0.97);

    --text-primary:   #f0f2ff;
    --text-secondary: #c4c9e2;
    --text-tertiary:  #7a8099;

    /* Bitcoin orange primary, amber-gold secondary */
    --accent-primary:   #f7931a;
    --accent-secondary: #fbbf24;
    --accent-gradient:  linear-gradient(135deg, #f7931a, #e88c00);

    /* Ethereum purple (Part 2) */
    --accent-eth:   #8b5cf6;
    /* Chain / data blue (visualisations) */
    --accent-chain: #22d3ee;
    /* Consensus green */
    --accent-ok:    #34d399;
    /* Error / attack red */
    --accent-danger:#f87171;

    --border-color: #1e2230;
    --border-hover: #2e3450;

    --shadow-sm: 0 2px 8px  rgba(0,0,0,0.45);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.50);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.55);

    --code-bg:       #07090e;
    --code-text:     #e8ecff;
    --code-keyword:  #c792ea;
    --code-string:   #c3e88d;
    --code-number:   #f78c6c;
    --code-function: #82aaff;
    --code-comment:  #546e7a;
    --code-orange:   #f7931a;

    --radius:    14px;
    --radius-sm:  8px;
    --radius-lg: 20px;
}

[data-theme="light"] {
    --bg-primary:    #f5f7fc;
    --bg-secondary:  #edf0f8;
    --bg-tertiary:   #e2e8f4;
    --bg-card:       #ffffff;
    --bg-card-hover: #f8faff;

    --text-primary:   #10131a;
    --text-secondary: #2d3452;
    --text-tertiary:  #5a637a;

    --accent-primary:   #d97706;
    --accent-secondary: #b45309;
    --accent-gradient:  linear-gradient(135deg, #d97706, #c06000);

    --accent-eth:   #7c3aed;
    --accent-chain: #0891b2;
    --accent-ok:    #059669;
    --accent-danger:#dc2626;

    --border-color: #d1d9ee;
    --border-hover: #a0aec0;

    --shadow-sm: 0 2px 8px  rgba(0,0,0,0.06);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.09);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.12);

    --code-bg:       #f1f5f9;
    --code-text:     #1e293b;
    --code-keyword:  #7c3aed;
    --code-string:   #059669;
    --code-number:   #ea580c;
    --code-function: #2563eb;
    --code-comment:  #64748b;
    --code-orange:   #d97706;
}

/* (reading progress bar styles are defined further below — two-element version) */

/* ── Module header bar ─────────────────────────────── */
.module-header-bar {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    padding: 0.6rem 2rem;
    /* Sticky: sticks just below the fixed navbar when scrolling */
    position: sticky;
    top: var(--navbar-h);
    z-index: 90;
    /* negative side margins let it span the full module-main column width */
    margin: 0 -2rem;
    padding-left: 2rem;
    padding-right: 2rem;
}
[data-theme="light"] .module-header-bar {
    background: rgba(255,255,255,0.97);
    backdrop-filter: blur(8px);
}

.module-badge-number {
    display: inline-block;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: #fff;
    background: var(--accent-gradient);
    padding: 0.25rem 0.75rem;
    border-radius: 100px;
    margin-bottom: 0.5rem;
}

.module-header-bar h1 {
    font-family: 'Playfair Display', serif;
    font-size: clamp(1.8rem, 5vw, 2.8rem);
    font-weight: 700;
    color: var(--text-primary);
    margin: 0 0 0.3rem;
}

.module-header-subtitle {
    font-size: 1.1rem;
    color: var(--text-tertiary);
    font-weight: 400;
    letter-spacing: 0.03em;
    margin: 0;
}

/* ── Layout: sidebar + main ─────────────────────────── */
.module-layout {
    display: flex;
    min-height: calc(100vh - 200px);
}

/* ── Sidebar ────────────────────────────────────────── */
.module-sidebar {
    position: fixed;
    top: var(--navbar-h); left: 0;
    width: 280px;
    height: calc(100vh - var(--navbar-h));
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    overflow-y: auto;
    z-index: 100;
    padding: 1.5rem 0;
    scrollbar-width: thin;
    scrollbar-color: var(--border-color) transparent;
}

.module-sidebar::-webkit-scrollbar { width: 4px; }
.module-sidebar::-webkit-scrollbar-track  { background: transparent; }
.module-sidebar::-webkit-scrollbar-thumb  { background: var(--border-color); border-radius: 2px; }

.sidebar-close-btn {
    display: none;
    position: absolute;
    top: 0.75rem; right: 0.75rem;
    background: none; border: none;
    color: var(--text-tertiary);
    cursor: pointer;
    padding: 0.25rem;
    border-radius: 6px;
    transition: background 0.2s, color 0.2s;
}
.sidebar-close-btn:hover { background: var(--bg-tertiary); color: var(--text-primary); }

.sidebar-header {
    padding: 0 1.25rem 1rem;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 0.75rem;
}

.sidebar-course-badge {
    display: inline-block;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.65rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--accent-primary);
    background: rgba(247,147,26, 0.12);
    padding: 0.15rem 0.5rem;
    border-radius: 100px;
    margin-bottom: 0.35rem;
}
[data-theme="light"] .sidebar-course-badge { background: rgba(217,119,6, 0.1); }

.sidebar-course-title {
    font-size: 1rem; font-weight: 600;
    color: var(--text-primary);
    margin: 0.25rem 0 0;
    line-height: 1.3;
}

.sidebar-nav { padding: 0 0.75rem; }

.sidebar-link {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    padding: 0.5rem 0.75rem;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.85rem;
    border-radius: var(--radius-sm);
    transition: all 0.2s;
    line-height: 1.3;
}
.sidebar-link:hover { background: var(--bg-tertiary); color: var(--text-primary); }
.sidebar-link.active {
    background: rgba(247,147,26, 0.1);
    color: var(--accent-primary);
    font-weight: 500;
}

.sidebar-link .link-number {
    display: flex; align-items: center; justify-content: center;
    width: 22px; height: 22px;
    font-size: 0.7rem; font-weight: 600;
    border-radius: 50%;
    background: var(--bg-tertiary);
    color: var(--text-tertiary);
    flex-shrink: 0;
}
.sidebar-link.active .link-number { background: var(--accent-primary); color: #fff; }

.back-to-course { margin-bottom: 0.5rem; font-weight: 500; color: var(--text-tertiary); }
.back-to-course:hover { color: var(--accent-primary); }

.sidebar-section { margin-bottom: 1rem; }

.sidebar-section-title {
    display: flex; align-items: center; gap: 0.5rem;
    padding: 0.5rem 0.75rem;
    font-size: 0.65rem; font-weight: 700;
    text-transform: uppercase; letter-spacing: 0.1em;
    color: var(--text-tertiary);
}
.sidebar-section-icon { font-size: 0.8rem; }

.module-link { font-size: 0.8rem; }

.module-dot {
    width: 8px; height: 8px;
    border-radius: 50%; flex-shrink: 0;
}

.sidebar-link.module-link.active-module {
    background: rgba(247,147,26, 0.08);
    color: var(--accent-primary);
    font-weight: 500;
}
.sidebar-link.module-link.disabled { opacity: 0.5; pointer-events: none; }

/* ── Main content area ──────────────────────────────── */
.module-main {
    padding: var(--navbar-h) 2rem 4rem;  /* top clears the fixed navbar */
    max-width: 900px;
    width: 100%;
    box-sizing: border-box;
    margin-left: max(280px, calc(50vw - 310px));
    margin-right: auto;
}

/* ── Lesson cards ───────────────────────────────────── */
.lesson-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 2rem 2.5rem;
    margin-bottom: 2rem;
    transition: border-color 0.3s, box-shadow 0.3s;
    scroll-margin-top: 80px;
}
.lesson-card:hover { border-color: var(--border-hover); box-shadow: var(--shadow-md); }

.lesson-card > h2 {
    font-family: 'Playfair Display', serif;
    font-size: 1.6rem; font-weight: 700;
    color: var(--text-primary);
    margin: 0 0 1rem; line-height: 1.3;
}
.lesson-card > h3 {
    font-size: 1.2rem; font-weight: 600;
    color: var(--text-primary);
    margin: 1.5rem 0 0.75rem;
}
.lesson-card > h4 {
    font-size: 1rem; font-weight: 600;
    color: var(--text-primary);
    margin: 1.2rem 0 0.5rem;
}
.lesson-card > p { color: var(--text-secondary); line-height: 1.7; margin: 0 0 1rem; }
.lesson-card > p:last-child { margin-bottom: 0; }
.lesson-card strong { color: var(--text-primary); font-weight: 600; }
.lesson-card em { color: var(--accent-primary); font-style: italic; }

.lesson-card code {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85em;
    background: var(--code-bg);
    color: var(--code-orange);
    padding: 0.15em 0.4em;
    border-radius: 5px;
    border: 1px solid var(--border-color);
}

.lesson-card ul, .lesson-card ol {
    color: var(--text-secondary);
    line-height: 1.7;
    margin: 0 0 1rem 1.2rem;
}
.lesson-card li { margin-bottom: 0.4rem; }
.lesson-card li strong { color: var(--text-primary); }

/* ── Info / callout cards ───────────────────────────── */
.info-card {
    border-radius: var(--radius-sm);
    padding: 1.25rem 1.5rem;
    margin: 1.2rem 0;
    border-left: 3px solid;
}
.info-card h3 { font-size: 1rem; font-weight: 600; margin: 0 0 0.6rem; }
.info-card ul { margin: 0 0 0 1.2rem; }

.info-card--orange {
    background: rgba(247,147,26, 0.08);
    border-color: var(--accent-primary);
}
.info-card--orange h3 { color: var(--accent-primary); }

.info-card--blue {
    background: rgba(34,211,238, 0.07);
    border-color: var(--accent-chain);
}
.info-card--blue h3 { color: var(--accent-chain); }

.info-card--green {
    background: rgba(52,211,153, 0.07);
    border-color: var(--accent-ok);
}
.info-card--green h3 { color: var(--accent-ok); }

.info-card--red {
    background: rgba(248,113,113, 0.08);
    border-color: var(--accent-danger);
}
.info-card--red h3 { color: var(--accent-danger); }

.info-card--purple {
    background: rgba(139,92,246, 0.08);
    border-color: var(--accent-eth);
}
.info-card--purple h3 { color: var(--accent-eth); }

[data-theme="light"] .info-card--orange { background: rgba(217,119,6, 0.06); }
[data-theme="light"] .info-card--blue   { background: rgba(8,145,178, 0.06); }
[data-theme="light"] .info-card--green  { background: rgba(5,150,105, 0.06); }
[data-theme="light"] .info-card--red    { background: rgba(220,38,38, 0.06); }
[data-theme="light"] .info-card--purple { background: rgba(124,58,237, 0.06); }

/* ── Code blocks ────────────────────────────────────── */
.code-block {
    background: var(--code-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    overflow: hidden;
    margin: 1.25rem 0;
    font-size: 0.88rem;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.18);
    transition: box-shadow 0.3s ease, border-color 0.3s ease;
}
.code-block:hover {
    box-shadow: 0 6px 24px rgba(0, 0, 0, 0.28);
    border-color: rgba(247, 147, 26, 0.25);
}
[data-theme="light"] .code-block {
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
}
[data-theme="light"] .code-block:hover {
    box-shadow: 0 6px 24px rgba(0, 0, 0, 0.12);
    border-color: rgba(217, 119, 6, 0.3);
}

.code-block-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.7rem 1.25rem;
    background: linear-gradient(135deg, rgba(247, 147, 26, 0.12), rgba(247, 147, 26, 0.03));
    border-bottom: 1px solid var(--border-color);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.78rem;
    font-weight: 500;
    color: var(--text-secondary);
}
[data-theme="light"] .code-block-header {
    background: linear-gradient(135deg, rgba(217, 119, 6, 0.08), rgba(217, 119, 6, 0.02));
}

/* macOS-style traffic light dots */
.code-dots {
    display: flex;
    gap: 6px;
    flex-shrink: 0;
}
.code-dots span {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    display: block;
}
.code-dots span:nth-child(1) { background: #ff5f57; }
.code-dots span:nth-child(2) { background: #febc2e; }
.code-dots span:nth-child(3) { background: #28c840; }

/* Filename label */
.code-filename {
    font-weight: 600;
    color: var(--text-primary);
    letter-spacing: 0.02em;
}

/* Language badge pill */
.code-lang-badge {
    margin-left: auto;
    background: rgba(247, 147, 26, 0.15);
    color: var(--accent-primary);
    padding: 0.2rem 0.65rem;
    border-radius: 20px;
    font-size: 0.68rem;
    font-weight: 600;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    flex-shrink: 0;
}
[data-theme="light"] .code-lang-badge {
    background: rgba(217, 119, 6, 0.1);
}
/* Terminal badge variant */
.code-lang-badge--terminal {
    background: rgba(34, 211, 238, 0.12);
    color: var(--accent-chain);
}
[data-theme="light"] .code-lang-badge--terminal {
    background: rgba(8, 145, 178, 0.1);
    color: #0891b2;
}
/* Pseudo-code badge variant */
.code-lang-badge--pseudo {
    background: rgba(139, 92, 246, 0.12);
    color: var(--accent-eth);
}
[data-theme="light"] .code-lang-badge--pseudo {
    background: rgba(124, 58, 237, 0.08);
    color: #7c3aed;
}

/* Syntax highlighting classes (alternative to inline styles) */
.hl-keyword  { color: var(--code-keyword);  font-weight: 600; }
.hl-string   { color: var(--code-string);   }
.hl-number   { color: var(--code-number);   }
.hl-comment  { color: var(--code-comment);  font-style: italic; }
.hl-function { color: var(--code-function); }
.hl-orange   { color: var(--code-orange);   }

.code-block pre {
    margin: 0;
    padding: 1.25rem 1.4rem;
    overflow-x: auto;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    line-height: 1.55;
    color: var(--code-text);
    tab-size: 2;
}
.code-block code,
.module-main section .code-block code {
    background: none;
    border: none;
    padding: 0;
    color: inherit;
    font-size: inherit;
    border-radius: 0;
}

/* ── Concept grid ───────────────────────────────────── */
.concept-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin: 1.2rem 0;
}
.concept-card {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: 1rem 1.2rem;
    transition: border-color 0.2s, transform 0.2s;
}
.concept-card:hover { border-color: var(--accent-primary); transform: translateY(-2px); }
.concept-card-icon { font-size: 1.5rem; margin-bottom: 0.4rem; }
.concept-card h4 { font-size: 0.9rem; font-weight: 600; color: var(--text-primary); margin: 0 0 0.3rem; }
.concept-card p  { font-size: 0.82rem; color: var(--text-tertiary); margin: 0; line-height: 1.5; }

/* ── Key-value data display (for block / tx anatomy) ── */
.data-display {
    background: var(--code-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    overflow: hidden;
    margin: 1rem 0;
    font-family: 'JetBrains Mono', monospace;
}
.data-display-header {
    display: flex; align-items: center; gap: 0.6rem;
    padding: 0.6rem 1rem;
    background: rgba(247,147,26, 0.08);
    border-bottom: 1px solid var(--border-color);
    font-size: 0.72rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em;
    color: var(--accent-primary);
}
.data-row {
    display: grid;
    grid-template-columns: 180px 1fr;
    gap: 0.5rem;
    padding: 0.55rem 1rem;
    border-bottom: 1px solid rgba(255,255,255,0.04);
    font-size: 0.82rem;
    align-items: start;
}
.data-row:last-child { border-bottom: none; }
.data-key {
    color: var(--text-tertiary);
    font-weight: 500;
    white-space: nowrap;
    display: flex; align-items: center; gap: 0.4rem;
}
.data-key .key-dot {
    width: 6px; height: 6px;
    border-radius: 50%; flex-shrink: 0;
    background: var(--border-color);
}
.data-value {
    color: var(--code-text);
    word-break: break-all;
    line-height: 1.5;
}
.data-value.val-orange { color: var(--code-orange); }
.data-value.val-green  { color: var(--accent-ok);   }
.data-value.val-blue   { color: var(--accent-chain); }
.data-value.val-purple { color: var(--accent-eth);  }
.data-annotation {
    font-family: 'Inter', sans-serif;
    font-size: 0.75rem;
    color: var(--text-tertiary);
    margin-top: 0.2rem;
    font-style: italic;
}

[data-theme="light"] .data-row { border-bottom-color: rgba(0,0,0,0.06); }
[data-theme="light"] .data-value { color: #1e293b; }

/* ── Chain diagram ──────────────────────────────────── */
.chain-diagram {
    display: flex;
    align-items: center;
    gap: 0;
    overflow-x: auto;
    padding: 1rem 0;
    margin: 1rem 0;
}
.chain-block {
    flex-shrink: 0;
    min-width: 140px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: 0.75rem;
    font-size: 0.78rem;
    font-family: 'JetBrains Mono', monospace;
    transition: border-color 0.2s, box-shadow 0.2s;
}
.chain-block:hover { border-color: var(--accent-primary); box-shadow: 0 0 10px rgba(247,147,26,0.2); }
.chain-block-label {
    font-size: 0.65rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em;
    color: var(--accent-primary); margin-bottom: 0.4rem;
}
.chain-block-hash {
    color: var(--text-tertiary); font-size: 0.72rem; word-break: break-all; line-height: 1.4;
    margin-bottom: 0.3rem;
}
.chain-block-data { color: var(--text-secondary); font-family: 'Inter', sans-serif; font-size: 0.78rem; }
.chain-arrow {
    flex-shrink: 0;
    padding: 0 0.5rem;
    color: var(--accent-primary);
    font-size: 1.2rem;
    opacity: 0.6;
}

/* ── Comparison table ───────────────────────────────── */
.compare-table {
    width: 100%; border-collapse: collapse;
    font-size: 0.88rem;
    margin: 1rem 0;
}
.compare-table th {
    text-align: left; padding: 0.6rem 1rem;
    background: var(--bg-tertiary);
    color: var(--text-primary); font-weight: 600;
    border-bottom: 2px solid var(--border-color);
}
.compare-table td {
    padding: 0.6rem 1rem;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-secondary); vertical-align: top;
}
.compare-table tr:hover td { background: rgba(255,255,255,0.02); }
[data-theme="light"] .compare-table tr:hover td { background: rgba(0,0,0,0.02); }

/* ── Badge / tag pills ──────────────────────────────── */
.tag-pills { display: flex; flex-wrap: wrap; gap: 0.4rem; margin: 0.6rem 0; }
.tag-pill {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.72rem; font-weight: 500;
    padding: 0.2rem 0.6rem;
    border-radius: 100px;
    background: var(--bg-tertiary);
    color: var(--text-tertiary);
    border: 1px solid var(--border-color);
}
.tag-pill--orange { background: rgba(247,147,26,0.12); color: var(--accent-primary);  border-color: rgba(247,147,26,0.25); }
.tag-pill--blue   { background: rgba(34,211,238,0.10); color: var(--accent-chain);    border-color: rgba(34,211,238,0.2); }
.tag-pill--green  { background: rgba(52,211,153,0.10); color: var(--accent-ok);        border-color: rgba(52,211,153,0.2); }
.tag-pill--purple { background: rgba(139,92,246,0.10); color: var(--accent-eth);       border-color: rgba(139,92,246,0.2); }
.tag-pill--red    { background: rgba(248,113,113,0.10); color: var(--accent-danger);   border-color: rgba(248,113,113,0.2); }

/* ── Timeline (Module 1) ───────────────────────────── */
.timeline {
    position: relative;
    padding-left: 2.2rem;
    margin: 2rem 0 2.4rem;
}
.timeline::before {
    content: '';
    position: absolute;
    left: 0.55rem;
    top: 0.3rem;
    bottom: 0.3rem;
    width: 2px;
    background: var(--border-color);
}
.timeline-item {
    position: relative;
    padding: 0 0 2rem 1.6rem;
}
.timeline-item:last-child { padding-bottom: 0; }
.timeline-item::before {
    content: '';
    position: absolute;
    left: -1.65rem;
    top: 0.35rem;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--text-muted);
    border: 2px solid var(--bg-card);
    box-shadow: 0 0 0 2px var(--border-color);
}
.timeline-item--btc::before {
    background: var(--accent-primary);
    box-shadow: 0 0 0 2px var(--accent-primary), 0 0 12px rgba(247,147,26,0.35);
    width: 12px;
    height: 12px;
    left: -1.72rem;
    top: 0.28rem;
}
.timeline-year {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--accent-primary);
    margin-bottom: 0.25rem;
    letter-spacing: 0.04em;
}
.timeline-content h4 {
    font-family: var(--font-heading);
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-primary);
    margin: 0 0 0.3rem;
}
.timeline-content p {
    font-size: 0.92rem;
    line-height: 1.55;
    color: var(--text-secondary);
    margin: 0;
}
.timeline-content .tag-pill {
    display: inline-block;
    margin-top: 0.35rem;
}
/* Neutralise global style.css .timeline-item (display:flex, hover translateX) */
.module-main .timeline-item,
.dd-container .timeline-item {
    display: block;
}
.module-main .timeline-item:hover,
.dd-container .timeline-item:hover {
    background: none;
    transform: none;
}
@media (max-width: 600px) {
    .timeline { padding-left: 1.6rem; }
    .timeline-item { padding-left: 1.2rem; }
    .timeline-item::before { left: -1.4rem; }
    .timeline-item--btc::before { left: -1.47rem; }
}

/* ── Deep-dive link (Know More) ─────────────────────── */
.deep-dive-link {
    display: flex; align-items: center; gap: 1.2rem;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--accent-eth);
    border-radius: var(--radius-sm);
    padding: 1.2rem 1.6rem;
    margin-top: 1.5rem;
    text-decoration: none;
    transition: all 0.3s;
}
.deep-dive-link:hover {
    border-color: var(--accent-eth);
    background: var(--bg-card-hover);
    box-shadow: 0 0 20px rgba(139,92,246,0.12);
    transform: translateY(-1px);
}
.deep-dive-icon {
    font-size: 1.6rem; flex-shrink: 0;
}
.deep-dive-link strong {
    display: block; font-size: 0.95rem;
    color: var(--accent-eth); margin-bottom: 0.2rem;
}
.deep-dive-link span {
    font-size: 0.82rem; color: var(--text-tertiary); line-height: 1.4;
}
@media (max-width: 600px) {
    .deep-dive-link { padding: 1rem; gap: 0.8rem; }
    .deep-dive-icon { font-size: 1.3rem; }
}

/* ── Code-block action bar (try-it + copy) ──────────── */
.code-block-actions {
    display: flex; align-items: center; justify-content: space-between;
    padding: 0.5rem 0.75rem;
    border-top: 1px solid var(--border-color);
    background: rgba(255,255,255,0.02);
    gap: 0.5rem;
}
.try-it-btn {
    display: inline-flex; align-items: center; gap: 0.55rem;
    background: none; border: none;
    padding: 0.4rem 0.6rem;
    border-radius: 6px;
    text-decoration: none;
    color: #60a5fa;
    font-size: 0.78rem;
    font-weight: 600;
    font-family: var(--font-body);
    letter-spacing: 0.01em;
    transition: all 0.25s ease;
    cursor: pointer;
}
.try-it-btn:hover {
    background: rgba(59,130,246,0.1);
    color: #93bbfd;
}
.try-it-icon {
    font-size: 0.65rem;
    display: inline-flex; align-items: center; justify-content: center;
    width: 1.3rem; height: 1.3rem;
    background: rgba(59,130,246,0.15);
    border-radius: 50%;
    flex-shrink: 0;
    transition: background 0.25s;
}
.try-it-btn:hover .try-it-icon {
    background: rgba(59,130,246,0.3);
}
.try-it-arrow {
    opacity: 0; transform: translateX(-4px);
    transition: all 0.25s;
    font-size: 0.85rem;
}
.try-it-btn:hover .try-it-arrow {
    opacity: 1; transform: translateX(0);
}
/* Copy button */
.copy-code-btn {
    display: inline-flex; align-items: center; gap: 0.4rem;
    background: none; border: 1px solid var(--border-color);
    padding: 0.35rem 0.7rem;
    border-radius: 6px;
    color: var(--text-tertiary);
    font-size: 0.75rem;
    font-weight: 500;
    font-family: var(--font-body);
    cursor: pointer;
    transition: all 0.25s ease;
    flex-shrink: 0;
}
.copy-code-btn:hover {
    background: rgba(255,255,255,0.06);
    color: var(--text-secondary);
    border-color: var(--text-tertiary);
}
.copy-code-btn.copied {
    border-color: rgba(34,197,94,0.4);
    color: #22c55e;
}
.copy-icon { font-size: 0.8rem; }
/* Light-mode overrides */
[data-theme="light"] .try-it-btn { color: #2563eb; }
[data-theme="light"] .try-it-btn:hover {
    background: rgba(37,99,235,0.08); color: #1d4ed8;
}
[data-theme="light"] .try-it-icon { background: rgba(37,99,235,0.1); }
[data-theme="light"] .try-it-btn:hover .try-it-icon { background: rgba(37,99,235,0.2); }
[data-theme="light"] .copy-code-btn:hover { background: rgba(0,0,0,0.04); }
[data-theme="light"] .code-block-actions { background: rgba(0,0,0,0.02); }
@media (max-width: 600px) {
    .code-block-actions { flex-wrap: wrap; }
    .try-it-btn { font-size: 0.74rem; }
    .copy-code-btn { font-size: 0.72rem; }
}

/* ── Next module box ────────────────────────────────── */
.next-module-box {
    display: flex; align-items: center; gap: 1.2rem;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1.5rem 2rem;
    text-decoration: none;
    transition: all 0.3s;
    margin-top: 1rem;
}
.next-module-box:hover {
    border-color: var(--accent-primary);
    box-shadow: 0 0 20px rgba(247,147,26,0.15);
    transform: translateY(-2px);
}
.next-module-badge {
    display: flex; align-items: center; justify-content: center;
    width: 44px; height: 44px; flex-shrink: 0;
    background: var(--accent-gradient);
    border-radius: 50%;
    font-size: 1.1rem; font-weight: 700; color: #fff;
    font-family: 'JetBrains Mono', monospace;
}
.next-module-content { flex: 1; min-width: 0; }
.next-label {
    display: flex; align-items: center; gap: 0.5rem;
    font-size: 0.72rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.1em;
    color: var(--accent-primary); margin-bottom: 0.3rem;
}
.next-module-content h3 { font-size: 1rem; font-weight: 600; color: var(--text-primary); margin: 0 0 0.3rem; }
.next-module-content p  { font-size: 0.85rem; color: var(--text-tertiary); margin: 0 0 0.5rem; }
.next-module-topics { display: flex; flex-wrap: wrap; gap: 0.3rem; }
.next-topic-pill {
    font-size: 0.72rem; font-family: 'JetBrains Mono', monospace;
    background: var(--bg-tertiary); color: var(--text-tertiary);
    border: 1px solid var(--border-color);
    padding: 0.15rem 0.5rem; border-radius: 100px;
}
.next-module-arrow { font-size: 1.4rem; color: var(--accent-primary); flex-shrink: 0; }

/* ── Progress tracker ───────────────────────────────── */
.next-progress {
    display: flex; align-items: center; gap: 0.4rem;
    margin-left: auto;
}
.next-progress-track {
    width: 60px; height: 4px;
    background: var(--bg-tertiary); border-radius: 2px; overflow: hidden;
}
.next-progress-fill { height: 100%; background: var(--accent-gradient); border-radius: 2px; }
.next-progress-text { font-size: 0.65rem; color: var(--text-tertiary); }

/* ── Summary grid ───────────────────────────────────── */
.summary-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem; margin: 1.2rem 0;
}
.summary-item {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: 1rem 1.2rem;
}
.summary-item h4 { font-size: 0.9rem; font-weight: 600; color: var(--text-primary); margin: 0 0 0.4rem; }
.summary-item p  { font-size: 0.82rem; color: var(--text-tertiary); margin: 0; line-height: 1.5; }

/* ── Mobile sidebar ─────────────────────────────────── */
.sidebar-mobile-toggle {
    display: none;
    position: fixed;
    bottom: 1.5rem; right: 1.5rem;
    width: 48px; height: 48px;
    background: var(--accent-gradient);
    border: none; border-radius: 50%;
    color: #fff; cursor: pointer;
    z-index: 200;
    align-items: center; justify-content: center;
    box-shadow: 0 4px 16px rgba(247,147,26,0.4);
    transition: transform 0.2s;
}
.sidebar-mobile-toggle:hover { transform: scale(1.08); }

.sidebar-backdrop {
    display: none;
    position: fixed; inset: 0;
    background: rgba(0,0,0,0.5);
    z-index: 99;
    backdrop-filter: blur(2px);
}
.sidebar-backdrop.active { display: block; }

/* ── Responsive ─────────────────────────────────────── */
@media (max-width: 900px) {
    .module-sidebar {
        transform: translateX(-100%);
        transition: transform 0.3s ease;
        top: 0; height: 100vh;
        padding-top: 3rem;
    }
    .module-sidebar.open { transform: translateX(0); }
    .sidebar-close-btn { display: flex; }
    .sidebar-mobile-toggle { display: flex; }
    .module-main {
        margin-left: 0;
        padding: 0 1.25rem 3rem;
    }
    .lesson-card { padding: 1rem 1rem; }
    .data-row { grid-template-columns: 1fr; gap: 0.2rem; }
    .data-key { font-size: 0.75rem; }
    .module-header-bar { padding: 0.5rem 1.25rem; }
    .module-header-bar h1 { font-size: clamp(1.4rem, 4vw, 2rem); }
    .concept-grid { grid-template-columns: 1fr 1fr; }
    .chain-diagram { gap: 0; }
}

@media (max-width: 600px) {
    .concept-grid { grid-template-columns: 1fr; }
    .summary-grid { grid-template-columns: 1fr; }
    .next-module-box { flex-direction: column; align-items: flex-start; gap: 0.8rem; padding: 1.2rem; }
    .next-module-arrow { display: none; }
    .compare-table { font-size: 0.78rem; }
    .compare-table th, .compare-table td { padding: 0.4rem 0.6rem; }
}

/* ════════════════════════════════════════════════════
   TEACHING MODE
   ════════════════════════════════════════════════════ */

/* ── Toggle button in .fixed-controls ─────────────── */
.tm-toggle-btn {
    display: flex; align-items: center; justify-content: center;
    width: 36px; height: 36px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-tertiary);
    cursor: pointer;
    transition: all 0.25s;
}
.tm-toggle-btn:hover,
.tm-toggle-btn--active {
    background: var(--accent-primary);
    border-color: var(--accent-primary);
    color: #fff;
    box-shadow: 0 0 14px rgba(247,147,26, 0.45);
}

/* ── Language toggle button in .fixed-controls ──────── */
.language-toggle-btn {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.4rem 0.75rem;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 100px;
    color: var(--text-secondary);
    font-size: 0.78rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    font-family: inherit;
    white-space: nowrap;
}
.language-toggle-btn:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-hover);
    color: var(--text-primary);
}
[data-theme="light"] .language-toggle-btn {
    background: #fff;
    border-color: var(--border-color);
    color: var(--text-secondary);
}
[data-theme="light"] .language-toggle-btn:hover {
    background: var(--bg-tertiary);
}

/* ── Teaching toolbar ──────────────────────────────── */
.teaching-toolbar {
    display: none; /* shown only when [data-teaching="true"] */
    position: fixed;
    top: 0; left: 0; right: 0;
    height: 56px;
    background: var(--bg-secondary);
    border-bottom: 2px solid var(--accent-primary);
    z-index: 10001;
    align-items: center;
    padding: 0 1rem;
    gap: 0.75rem;
    box-shadow: 0 2px 16px rgba(0,0,0,0.5);
}
[data-theme="light"] .teaching-toolbar {
    border-bottom-color: var(--accent-primary);
    box-shadow: 0 2px 16px rgba(0,0,0,0.12);
}

/* ── Active: hide chrome, show toolbar ─────────────── */
[data-teaching="true"] .teaching-toolbar { display: flex; }

[data-teaching="true"] .navbar,
[data-teaching="true"] .reading-progress,
[data-teaching="true"] .fixed-controls,
[data-teaching="true"] .sidebar-mobile-toggle,
[data-teaching="true"] .sidebar-backdrop,
[data-teaching="true"] .module-header-bar,
[data-teaching="true"] .module-sidebar {
    display: none !important;
}

[data-teaching="true"] .module-layout {
    display: block;
}

[data-teaching="true"] .module-main {
    margin: 0 auto;
    padding: 1.5rem 2rem 4rem;
    max-width: 860px;
    /* Push content below the toolbar */
    padding-top: calc(56px + 1.5rem);
}

/* ── Section focus / dim ───────────────────────────── */
section[data-tm-focus],
.dd-section[data-tm-focus] {
    transition: opacity 0.35s ease;
}
section[data-tm-focus="active"],
.dd-section[data-tm-focus="active"] { opacity: 1; }
section[data-tm-focus="dim"],
.dd-section[data-tm-focus="dim"]    { opacity: 0.25; cursor: pointer; }

/* ── Toolbar nav buttons ───────────────────────────── */
.tm-nav-btn {
    display: flex; align-items: center; justify-content: center;
    width: 40px; height: 40px; flex-shrink: 0;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s;
}
.tm-nav-btn:hover:not(:disabled) {
    background: var(--accent-primary);
    border-color: var(--accent-primary);
    color: #fff;
}
.tm-nav-btn:disabled { opacity: 0.3; cursor: not-allowed; }

/* ── Center section info ───────────────────────────── */
.tm-center {
    flex: 1; min-width: 0;
    display: flex; align-items: center;
    justify-content: center;
    gap: 0.6rem; overflow: hidden;
}
.tm-module-name {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.68rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.1em;
    color: var(--accent-primary);
    flex-shrink: 0;
}
.tm-sep { color: var(--text-tertiary); flex-shrink: 0; font-size: 0.8rem; }
.tm-title {
    font-size: 0.9rem; font-weight: 600;
    color: var(--text-primary);
    white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.tm-counter {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.72rem;
    color: var(--text-tertiary);
    flex-shrink: 0;
    background: var(--bg-tertiary);
    padding: 0.18rem 0.55rem;
    border-radius: 100px;
    border: 1px solid var(--border-color);
}

/* ── Exit button ───────────────────────────────────── */
.tm-exit-btn {
    display: flex; align-items: center; gap: 0.4rem;
    padding: 0.4rem 0.8rem; flex-shrink: 0;
    background: rgba(248,113,113, 0.1);
    border: 1px solid rgba(248,113,113, 0.3);
    border-radius: 8px;
    color: var(--accent-danger);
    font-size: 0.8rem; font-weight: 600;
    cursor: pointer; transition: all 0.2s;
}
.tm-exit-btn:hover { background: var(--accent-danger); color: #fff; border-color: var(--accent-danger); }

/* ── Zoom controls ─────────────────────────────────── */
.tm-zoom-group {
    display: flex;
    align-items: center;
    gap: 0;
    flex-shrink: 0;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    overflow: hidden;
}
.tm-zoom-btn {
    display: flex; align-items: center; justify-content: center;
    width: 30px; height: 30px;
    background: var(--bg-tertiary);
    border: none;
    color: var(--text-secondary);
    font-size: 1.1rem; font-weight: 700; line-height: 1;
    cursor: pointer;
    transition: background 0.15s, color 0.15s;
    flex-shrink: 0;
}
.tm-zoom-btn:hover:not(:disabled) {
    background: var(--accent-primary);
    color: #fff;
}
.tm-zoom-btn:disabled { opacity: 0.3; cursor: not-allowed; }
.tm-zoom-level {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.68rem; font-weight: 700;
    color: var(--text-tertiary);
    background: var(--bg-secondary);
    padding: 0 0.45rem;
    min-width: 38px;
    text-align: center;
    border-left: 1px solid var(--border-color);
    border-right: 1px solid var(--border-color);
    line-height: 30px;
    white-space: nowrap;
}
.tm-keyboard-hint {
    position: fixed;
    bottom: 2rem; left: 50%;
    transform: translateX(-50%);
    background: rgba(10, 12, 16, 0.9);
    color: #f0f2ff;
    font-size: 0.82rem; font-weight: 500;
    padding: 0.65rem 1.4rem;
    border-radius: 100px;
    border: 1px solid var(--border-color);
    z-index: 10002;
    pointer-events: none;
    white-space: nowrap;
    animation: tmHintFade 4s ease forwards;
}
[data-theme="light"] .tm-keyboard-hint { background: rgba(16,19,26,0.85); }

@keyframes tmHintFade {
    0%   { opacity: 0; transform: translateX(-50%) translateY(8px); }
    15%  { opacity: 1; transform: translateX(-50%) translateY(0); }
    70%  { opacity: 1; }
    100% { opacity: 0; }
}

/* ── Teaching mode responsive ──────────────────────── */
@media (max-width: 600px) {
    .teaching-toolbar { padding: 0 0.75rem; gap: 0.5rem; }
    .tm-title { display: none; }
    .tm-sep   { display: none; }
    .teaching-toolbar .tm-center { gap: 0.4rem; }
    [data-teaching="true"] .module-main { padding: 1rem 1rem 3rem; padding-top: calc(56px + 1rem); }
    .tm-keyboard-hint { font-size: 0.72rem; padding: 0.5rem 1rem; }
}

/* ════════════════════════════════════════════════════
   MODULE HEADER BAR  &  MODULE HERO
   ════════════════════════════════════════════════════ */

/* (module-header-bar rules consolidated above — no duplicate needed) */
.back-link {
    font-size: 0.8rem; font-weight: 500;
    color: var(--text-tertiary);
    text-decoration: none;
    transition: color 0.2s;
}
.back-link:hover { color: var(--accent-primary); }
.module-meta-label {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem; font-weight: 600; text-transform: uppercase; letter-spacing: 0.08em;
    color: var(--text-tertiary);
}
.module-eyebrow {
    font-size: 0.75rem; font-weight: 500;
    color: var(--accent-primary);
    margin-left: auto;
}

/* Module hero (inside module-main, above sections) */
.module-hero {
    padding: 2.5rem 0 2rem;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 2rem;
}
.module-hero h1 {
    font-family: 'Playfair Display', serif;
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 700;
    color: var(--text-primary);
    margin: 0 0 0.5rem;
    line-height: 1.2;
}
.module-hero-sub {
    font-size: 1.05rem;
    color: var(--text-secondary);
    max-width: 680px;
    line-height: 1.65;
    margin: 0 0 1rem;
}
.module-hero-meta {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
}
.module-hero-meta span {
    display: flex; align-items: center; gap: 0.3rem;
    font-size: 0.8rem;
    color: var(--text-tertiary);
    font-family: 'JetBrains Mono', monospace;
}

/* ════════════════════════════════════════════════════
   READING PROGRESS BAR  (two-element version)
   ════════════════════════════════════════════════════ */
.reading-progress {
    position: fixed;
    top: 0; left: 0;
    width: 100%;
    height: 3px;
    z-index: 10000;
    background: transparent;
}
.reading-progress-bar {
    height: 100%;
    width: 0;
    background: var(--accent-gradient);
    transition: width 0.1s linear;
}

/* ════════════════════════════════════════════════════
   SIDEBAR — EXTENDED STYLES
   ════════════════════════════════════════════════════ */
.sidebar-module-label {
    padding: 0 1.25rem 0.5rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.65rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.1em;
    color: var(--accent-primary);
}
.sidebar-sections {
    display: flex; flex-direction: column;
    padding: 0 0.75rem;
    margin-bottom: 0.5rem;
}
.sidebar-divider {
    height: 1px;
    background: var(--border-color);
    margin: 0.75rem 1.25rem;
}
.sidebar-all-modules {
    padding: 0 0.75rem;
    display: flex; flex-direction: column;
}
.sidebar-all-title {
    font-size: 0.65rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.1em;
    color: var(--text-tertiary);
    padding: 0 0.75rem;
    margin-bottom: 0.25rem;
}
.sidebar-module-item {
    display: block;
    padding: 0.35rem 0.75rem;
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-decoration: none;
    border-radius: 6px;
    transition: all 0.2s;
    white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.sidebar-module-item:hover { background: var(--bg-tertiary); color: var(--text-primary); }
.sidebar-module-item.active {
    background: rgba(247,147,26,0.1);
    color: var(--accent-primary);
    font-weight: 600;
}
.sidebar-module-item.disabled { opacity: 0.4; pointer-events: none; }

.sidebar-part-label {
    padding: 0.6rem 0.75rem 0.15rem;
    font-size: 0.62rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.1em;
    color: var(--text-tertiary);
}

/* ════════════════════════════════════════════════════
   LESSON CARD — ICON VARIANT (flex row)
   Overrides the base .lesson-card above with flex layout
   and tighter padding for the icon+text pattern.
   ════════════════════════════════════════════════════ */
.lesson-card {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    padding: 1.25rem 1.5rem;   /* tighter than the base 2rem 2.5rem */
}
.lesson-card .card-icon {
    font-size: 1.4rem;
    flex: 0 0 auto;            /* NEVER grow/shrink — fixes the 50% width bug */
    line-height: 1;
    margin-top: 0.15rem;
}
/* only the content wrapper div grows, NOT .card-icon */
.lesson-card > div:not(.card-icon) { flex: 1; min-width: 0; }
.lesson-card h3 { font-size: 1rem; font-weight: 600; color: var(--text-primary); margin: 0 0 0.4rem; }
.lesson-card p  { color: var(--text-secondary); line-height: 1.7; margin: 0; font-size: 0.9rem; }
.lesson-card p a { color: var(--accent-primary); text-decoration: underline; text-underline-offset: 2px; }

/* Colour variants */
.card-orange { border-left: 3px solid var(--accent-primary); background: rgba(247,147,26,0.05); }
.card-blue   { border-left: 3px solid var(--accent-chain);  background: rgba(34,211,238,0.05); }
.card-green  { border-left: 3px solid var(--accent-ok);     background: rgba(52,211,153,0.05); }
.card-red    { border-left: 3px solid var(--accent-danger);  background: rgba(248,113,113,0.05); }
.card-purple { border-left: 3px solid var(--accent-eth);    background: rgba(139,92,246,0.05); }
[data-theme="light"] .card-orange { background: rgba(217,119,6,0.04); }
[data-theme="light"] .card-blue   { background: rgba(8,145,178,0.04); }
[data-theme="light"] .card-green  { background: rgba(5,150,105,0.04); }
[data-theme="light"] .card-red    { background: rgba(220,38,38,0.04); }
[data-theme="light"] .card-purple { background: rgba(124,58,237,0.04); }

/* ════════════════════════════════════════════════════
   LISTS
   ════════════════════════════════════════════════════ */
.check-list, .cross-list, .dash-list {
    list-style: none;
    margin: 0.5rem 0;
    padding: 0;
}
.check-list li, .cross-list li, .dash-list li {
    display: flex; align-items: flex-start; gap: 0.6rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
    margin-bottom: 0.4rem;
}
.check-list li::before { content: '✓'; color: var(--accent-ok);     font-weight: 700; flex-shrink: 0; }
.cross-list li::before { content: '✗'; color: var(--accent-danger);  font-weight: 700; flex-shrink: 0; }
.dash-list  li::before { content: '–'; color: var(--text-tertiary); font-weight: 700; flex-shrink: 0; }

/* ════════════════════════════════════════════════════
   TWO-COLUMN INFO LAYOUT
   ════════════════════════════════════════════════════ */
.two-column-info {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    margin: 1.5rem 0;
}
.info-col {
    min-width: 0;            /* prevent grid blow-out on long content */
}
.info-col-title {
    font-size: 0.8rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em;
    color: var(--accent-ok);
    margin: 0 0 0.75rem;
}
.red-title { color: var(--accent-danger); }
@media (max-width: 640px) { .two-column-info { grid-template-columns: 1fr; } }

/* ════════════════════════════════════════════════════
   BITCOIN TRANSACTION CARD
   ════════════════════════════════════════════════════ */
.tx-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    overflow: hidden;
    margin: 1.5rem 0;
    box-shadow: var(--shadow-md);
}
.tx-card-header {
    display: flex; align-items: center; justify-content: space-between;
    padding: 0.75rem 1.25rem;
    background: rgba(247,147,26,0.07);
    border-bottom: 1px solid var(--border-color);
}
.tx-badge {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.65rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.1em;
    background: var(--accent-gradient);
    color: #fff;
    padding: 0.2rem 0.65rem;
    border-radius: 100px;
}
.tx-status {
    display: flex; align-items: center; gap: 0.45rem;
    font-size: 0.8rem; font-weight: 600; color: var(--accent-ok);
}
.tx-status-dot {
    width: 8px; height: 8px;
    border-radius: 50%;
    background: var(--accent-ok);
    box-shadow: 0 0 6px var(--accent-ok);
    animation: pulseDot 2s ease infinite;
}
@keyframes pulseDot {
    0%, 100% { opacity: 1; transform: scale(1); }
    50%       { opacity: 0.6; transform: scale(0.85); }
}
.tx-id-row {
    display: flex; align-items: center; flex-wrap: wrap; gap: 0.75rem;
    padding: 0.75rem 1.25rem;
    border-bottom: 1px solid var(--border-color);
}
.tx-id-label { font-size: 0.75rem; color: var(--text-tertiary); font-weight: 500; flex-shrink: 0; }
.tx-id-value {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.78rem;
    color: var(--accent-chain);
    word-break: break-all;
    flex: 1;
    line-height: 1.5;
}
.tx-meta-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    border-bottom: 1px solid var(--border-color);
}
.tx-meta-item {
    padding: 0.65rem 1rem;
    border-right: 1px solid var(--border-color);
    display: flex; flex-direction: column; gap: 0.2rem;
}
.tx-meta-item:last-child { border-right: none; }
.tx-meta-key { font-size: 0.68rem; color: var(--text-tertiary); text-transform: uppercase; letter-spacing: 0.07em; }
.tx-meta-val { font-family: 'JetBrains Mono', monospace; font-size: 0.85rem; font-weight: 600; color: var(--text-primary); }
.tx-flow {
    display: flex; align-items: stretch; gap: 0;
    padding: 1rem 1.25rem;
    border-bottom: 1px solid var(--border-color);
}
.tx-side { flex: 1; display: flex; flex-direction: column; gap: 0.5rem; }
.tx-side-title {
    font-size: 0.65rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em;
    color: var(--text-tertiary);
    margin-bottom: 0.25rem;
}
.tx-input-item, .tx-output-item {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: 0.6rem 0.85rem;
    display: flex; align-items: center; justify-content: space-between; gap: 0.5rem;
}
.tx-input-item { border-color: var(--accent-danger); background: rgba(248,113,113,0.05); }
.tx-output-item { border-color: var(--accent-ok); background: rgba(52,211,153,0.05); }
.tx-io-label { display: flex; align-items: center; gap: 0.4rem; min-width: 0; }
.tx-io-tag {
    font-size: 0.6rem; font-weight: 700; text-transform: uppercase;
    background: var(--bg-secondary); padding: 0.1rem 0.4rem; border-radius: 4px;
    color: var(--text-tertiary); flex-shrink: 0;
}
.tx-io-label code {
    font-family: 'JetBrains Mono', monospace; font-size: 0.78rem;
    color: var(--text-secondary); white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.tx-io-amount {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.88rem; font-weight: 700;
    color: var(--accent-secondary);
    flex-shrink: 0;
}
.tx-arrow {
    display: flex; align-items: center; justify-content: center;
    padding: 0 1rem;
    color: var(--accent-primary);
    flex-shrink: 0;
}
.tx-total-row {
    display: flex; align-items: center; justify-content: space-between;
    padding: 0.7rem 1.25rem;
    font-size: 0.85rem;
    color: var(--text-tertiary);
}
.tx-total-row strong {
    font-family: 'JetBrains Mono', monospace;
    color: var(--accent-primary); font-size: 1rem; font-weight: 700;
}
@media (max-width: 580px) {
    .tx-meta-grid { grid-template-columns: repeat(2, 1fr); }
    .tx-flow { flex-direction: column; }
    .tx-arrow { transform: rotate(90deg); padding: 0.5rem 0; }
}

/* ════════════════════════════════════════════════════
   QUESTIONS CARD
   ════════════════════════════════════════════════════ */
.questions-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 2rem 2rem 1.5rem;
    margin: 1.5rem 0;
    border-top: 3px solid var(--accent-secondary);
}
.questions-card h3 {
    font-size: 0.85rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em;
    color: var(--accent-secondary); margin: 0 0 1.2rem;
}
.question-list {
    list-style: none; margin: 0; padding: 0;
    counter-reset: q-counter;
}
.question-list li {
    counter-increment: q-counter;
    color: var(--text-secondary);
    font-size: 0.92rem;
    line-height: 1.65;
    padding: 1.1rem 1.2rem 1.1rem 3.8rem;
    border-radius: var(--radius-sm);
    transition: background 0.2s;
    position: relative;
}
.question-list li:not(:last-child) {
    border-bottom: 1px solid rgba(128, 128, 128, 0.1);
}
.question-list li:hover {
    background: rgba(247, 147, 26, 0.03);
}
.question-list li::before {
    content: counter(q-counter);
    position: absolute;
    left: 1.2rem;
    top: 1.15rem;
    display: flex; align-items: center; justify-content: center;
    width: 30px; height: 30px;
    border-radius: 50%;
    background: var(--accent-gradient);
    color: #fff;
    font-size: 0.78rem; font-weight: 700;
    font-family: 'JetBrains Mono', monospace;
    box-shadow: 0 2px 8px rgba(247, 147, 26, 0.25);
}
.question-list li strong {
    color: var(--text-primary);
    font-weight: 700;
    margin-right: 0.15rem;
}
.question-list li code {
    background: rgba(247, 147, 26, 0.08);
    color: var(--accent-primary);
    padding: 0.15rem 0.5rem;
    border-radius: 4px;
    font-size: 0.84rem;
    border: 1px solid rgba(247, 147, 26, 0.15);
    word-break: break-word;
}

/* ════════════════════════════════════════════════════
   ANATOMY TABLE  (TX fields)
   ════════════════════════════════════════════════════ */
.anatomy-table {
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    overflow: hidden;
    margin: 1.5rem 0;
}
.anatomy-row {
    display: grid;
    grid-template-columns: 180px 1fr;
    gap: 0;
    border-bottom: 1px solid var(--border-color);
    transition: background 0.2s;
}
.anatomy-row:last-child { border-bottom: none; }
.anatomy-row:hover { background: rgba(255,255,255,0.02); }
[data-theme="light"] .anatomy-row:hover { background: rgba(0,0,0,0.02); }
.anatomy-field {
    padding: 0.85rem 1rem;
    background: var(--bg-tertiary);
    border-right: 1px solid var(--border-color);
    display: flex; align-items: center;
}
.anatomy-field code {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.82rem; font-weight: 600;
    color: var(--accent-primary);
    background: none; border: none; padding: 0;
}
.anatomy-desc {
    padding: 0.85rem 1.25rem;
    color: var(--text-secondary);
    font-size: 0.88rem; line-height: 1.6;
    display: flex; align-items: center;
}
@media (max-width: 560px) {
    .anatomy-row { grid-template-columns: 1fr; }
    .anatomy-field { border-right: none; border-bottom: 1px solid var(--border-color); padding: 0.6rem 1rem 0.4rem; }
    .anatomy-desc  { padding: 0.5rem 1rem 0.75rem; }
}

/* ════════════════════════════════════════════════════
   BLOCK DIAGRAM
   ════════════════════════════════════════════════════ */
.block-diagram {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    overflow: hidden;
    margin: 1.5rem 0;
    box-shadow: var(--shadow-sm);
}
.block-diagram-label {
    padding: 0.6rem 1.25rem;
    background: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.68rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.1em;
    color: var(--accent-primary);
}
.block-header-box {
    border-bottom: 1px solid var(--border-color);
}
.block-header-title {
    padding: 0.55rem 1.25rem;
    font-size: 0.7rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em;
    color: var(--text-tertiary);
    background: rgba(247,147,26,0.04);
    border-bottom: 1px solid var(--border-color);
}
.block-header-field {
    display: grid;
    grid-template-columns: 180px auto 1fr;
    gap: 0.75rem;
    align-items: start;
    padding: 0.65rem 1.25rem;
    border-bottom: 1px solid var(--border-color);
    transition: background 0.2s;
}
.block-header-field:last-child { border-bottom: none; }
.block-header-field:hover { background: rgba(255,255,255,0.02); }
[data-theme="light"] .block-header-field:hover { background: rgba(0,0,0,0.02); }
.bf-name {
    font-size: 0.8rem; font-weight: 600;
    color: var(--text-primary);
    padding-top: 0.1rem;
}
.bf-val {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.78rem;
    color: var(--accent-chain);
    background: var(--code-bg);
    padding: 0.15rem 0.5rem;
    border-radius: 5px;
    border: 1px solid var(--border-color);
    white-space: nowrap;
}
.bf-desc {
    font-size: 0.8rem;
    color: var(--text-tertiary);
    line-height: 1.5;
    margin: 0;
    grid-column: 3;
}
/* No bf-val for some fields — span all */
.block-header-field { grid-template-columns: 180px auto 1fr; }

/* coloured left border hints */
.highlight-prev   { border-left: 3px solid var(--accent-primary); }
.highlight-merkle { border-left: 3px solid var(--accent-chain); }
.highlight-diff   { border-left: 3px solid var(--accent-eth); }
.highlight-nonce  { border-left: 3px solid var(--accent-ok); }

.block-txs-box { padding: 0.75rem 1.25rem; }
.btx-label {
    font-size: 0.65rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em;
    color: var(--text-tertiary); margin-bottom: 0.4rem;
}
.btx-item {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.82rem; color: var(--text-secondary);
}
.btx-item code { color: var(--accent-chain); background: none; border: none; padding: 0; }

@media (max-width: 580px) {
    .block-header-field { grid-template-columns: 1fr; gap: 0.25rem; }
    .bf-desc { grid-column: 1; }
}

/* ════════════════════════════════════════════════════
   BIG QUESTION
   ════════════════════════════════════════════════════ */
.big-question {
    display: flex; align-items: flex-start; gap: 1.5rem;
    background: linear-gradient(135deg, rgba(247,147,26,0.1), rgba(251,191,36,0.06));
    border: 1px solid rgba(247,147,26,0.3);
    border-radius: var(--radius);
    padding: 2rem 2rem 2rem 1.5rem;
    margin: 1.5rem 0;
}
.big-question-mark {
    font-size: 4rem; line-height: 1;
    color: var(--accent-primary);
    font-weight: 900;
    font-family: 'Playfair Display', serif;
    flex-shrink: 0;
}
.big-question p {
    font-size: 1.3rem; font-weight: 600;
    color: var(--text-primary);
    line-height: 1.45;
    margin: 0;
    padding-top: 0.75rem;
}

/* ════════════════════════════════════════════════════
   THREE CONCEPTS GRID
   ════════════════════════════════════════════════════ */
.three-concepts {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1rem;
    margin: 1.5rem 0;
}
.concept-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1.5rem 1.25rem;
    display: flex; flex-direction: column; gap: 0.6rem;
    transition: border-color 0.2s, transform 0.2s;
}
.concept-card:hover { border-color: var(--accent-primary); transform: translateY(-2px); }
.concept-num {
    display: flex; align-items: center; justify-content: center;
    width: 34px; height: 34px;
    background: var(--accent-gradient);
    color: #fff;
    border-radius: 50%;
    font-weight: 700; font-size: 0.9rem;
    font-family: 'JetBrains Mono', monospace;
    flex-shrink: 0;
}
.concept-card h4 {
    font-size: 0.95rem; font-weight: 600;
    color: var(--text-primary); margin: 0;
}
.concept-card p {
    font-size: 0.82rem; color: var(--text-secondary);
    line-height: 1.55; margin: 0;
}
@media (max-width: 640px) { .three-concepts { grid-template-columns: 1fr; } }

/* ════════════════════════════════════════════════════
   ROADMAP PARTS
   ════════════════════════════════════════════════════ */
.roadmap-parts {
    display: flex; flex-direction: column; gap: 0;
    margin: 1.5rem 0;
}
.roadmap-part {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1.5rem 1.75rem;
    transition: border-color 0.2s;
}
.roadmap-part:hover { border-color: var(--border-hover); }
.roadmap-part--btc { border-left: 4px solid var(--accent-primary); }
.roadmap-part--eth { border-left: 4px solid var(--accent-eth); }
.roadmap-part--ent { border-left: 4px solid var(--accent-chain); }
.roadmap-part-header {
    display: flex; align-items: center; gap: 1rem;
    margin-bottom: 0.75rem;
}
.roadmap-badge {
    display: flex; align-items: center; justify-content: center;
    width: 40px; height: 40px; flex-shrink: 0;
    background: var(--bg-tertiary);
    border-radius: 50%;
    font-size: 1.2rem;
    border: 1px solid var(--border-color);
}
.roadmap-part h3 { font-size: 1rem; font-weight: 700; color: var(--text-primary); margin: 0 0 0.15rem; }
.roadmap-modules {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem; font-weight: 600;
    color: var(--text-tertiary);
}
.roadmap-part p  { font-size: 0.88rem; color: var(--text-secondary); line-height: 1.6; margin: 0; }
.roadmap-arrow-down {
    text-align: center;
    font-size: 1.5rem;
    color: var(--text-tertiary);
    padding: 0.25rem 0;
}

/* ════════════════════════════════════════════════════
   PREREQUISITES GRID
   ════════════════════════════════════════════════════ */
.prereq-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    margin: 1.5rem 0;
}
.prereq-title {
    font-size: 0.78rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em;
    margin: 0 0 0.75rem;
}
.must-title { color: var(--accent-ok); }
.nice-title { color: var(--text-tertiary); }
@media (max-width: 640px) { .prereq-grid { grid-template-columns: 1fr; } }

/* ════════════════════════════════════════════════════
   INSTALL LIST
   ════════════════════════════════════════════════════ */
.install-list {
    display: flex; flex-direction: column; gap: 0;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    overflow: hidden;
    margin: 1.25rem 0;
}
.install-item {
    display: flex; align-items: center; gap: 1rem;
    padding: 0.75rem 1.25rem;
    border-bottom: 1px solid var(--border-color);
    transition: background 0.2s;
}
.install-item:last-child { border-bottom: none; }
.install-item:hover { background: var(--bg-tertiary); }
.install-item code {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem; font-weight: 600;
    color: var(--accent-primary);
    background: var(--code-bg);
    padding: 0.2rem 0.5rem;
    border-radius: 5px;
    border: 1px solid var(--border-color);
    min-width: 90px; flex-shrink: 0;
}
.install-item span { flex: 1; font-size: 0.88rem; color: var(--text-secondary); }
.install-item a {
    font-size: 0.85rem; font-weight: 600;
    color: var(--accent-chain);
    text-decoration: none;
    padding: 0.2rem 0.5rem;
    border-radius: 5px;
    transition: background 0.2s;
}
.install-item a:hover { background: rgba(34,211,238,0.1); }

/* ════════════════════════════════════════════════════
   NEXT MODULE BOX  (text version used in module0)
   ════════════════════════════════════════════════════ */
.next-module-box {
    flex-direction: column;
    align-items: stretch;
    gap: 0.75rem;
    margin-top: 3rem;
}
.next-module-box .next-label {
    font-size: 0.72rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.1em;
    color: var(--accent-primary); margin: 0;
}
.next-module-box p {
    font-size: 0.92rem; color: var(--text-secondary); line-height: 1.6; margin: 0;
}
.btn-next {
    display: inline-block;
    background: var(--accent-gradient);
    color: #fff;
    font-weight: 600; font-size: 0.9rem;
    padding: 0.7rem 1.5rem;
    border-radius: var(--radius-sm);
    text-decoration: none;
    transition: opacity 0.2s, transform 0.2s;
    width: fit-content;
}
.btn-next:hover { opacity: 0.9; transform: translateX(3px); }

/* ════════════════════════════════════════════════════
   section heading & general spacing
   ════════════════════════════════════════════════════ */
.module-main section {
    scroll-margin-top: 90px;
    padding-bottom: 2.5rem;
    margin-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-color);
}
.module-main section:last-child { border-bottom: none; }
.module-main section h2 {
    font-family: 'Playfair Display', serif;
    font-size: clamp(1.5rem, 3.5vw, 2rem);
    font-weight: 700;
    color: var(--text-primary);
    margin: 0 0 1.25rem;
    padding-top: 2rem;
    line-height: 1.2;
}
.module-main section h3 {
    font-size: 1.1rem; font-weight: 600;
    color: var(--text-primary);
    margin: 1.5rem 0 0.75rem;
}
.module-main section p {
    color: var(--text-secondary);
    line-height: 1.7;
    margin: 0 0 1rem;
}
.module-main section code {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85em;
    background: var(--code-bg);
    color: var(--code-orange);
    padding: 0.15em 0.4em;
    border-radius: 5px;
    border: 1px solid var(--border-color);
}
/* Reset inline-code styling inside code blocks (high specificity override) */
.module-main section .code-block pre code {
    background: none;
    border: none;
    padding: 0;
    color: inherit;
    font-size: inherit;
    border-radius: 0;
}