/* ================================================================
   FTC-26 Programming Curriculum  —  Light Mode
   Typefaces: Exo 2 (display) · Outfit (body) · JetBrains Mono (code)
   ================================================================ */

:root {
    /* Backgrounds */
    --bg:          #f2f1ed;
    --bg-sidebar:  #ffffff;
    --bg-card:     #ffffff;
    --bg-card-alt: #fafaf8;

    /* Borders */
    --border:       #e2e0da;
    --border-strong:#c8c5bc;

    /* Accent — High Voltage yellow */
    --accent:        #f0c000;
    --accent-light:  #fffbe0;
    --accent-mid:    rgba(240, 192, 0, 0.12);
    --accent-glow:   rgba(240, 192, 0, 0.45);
    --accent-border: rgba(240, 192, 0, 0.35);

    /* Secondary accent — slate blue */
    --blue:         #2563eb;
    --blue-light:   #eff3ff;

    /* Text */
    --text:         #0a0a0a;
    --text-muted:   #444444;
    --text-dim:     #a0a0a0;

    /* Tag palette */
    --tag-java:     #0ea5e9;
    --tag-ftc:      #e03a00;
    --tag-hardware: #d97706;
    --tag-teleop:   #16a34a;
    --tag-drive:    #7c3aed;
    --tag-arch:     #db2777;
    --tag-auto:     #2563eb;
    --tag-vision:   #0d9488;
    --tag-comp:     #b45309;

    /* Layout */
    --sidebar-w:    256px;
    --radius:       7px;
    --radius-sm:    4px;

    /* Fonts */
    --f-display: 'Exo 2', sans-serif;
    --f-body:    'Outfit', sans-serif;
    --f-mono:    'JetBrains Mono', monospace;
}

/* ── Reset ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
    background: var(--bg);
    color: var(--text);
    font-family: var(--f-body);
    font-size: 15px;
    line-height: 1.65;
    min-height: 100vh;
    overflow: hidden;
}

button { font-family: inherit; cursor: pointer; }

/* Subtle dot-grid over the background */
body::before {
    content: '';
    position: fixed;
    inset: 0;
    background-image: radial-gradient(circle, #cccac4 1px, transparent 1px);
    background-size: 26px 26px;
    opacity: 0.55;
    pointer-events: none;
    z-index: 0;
}

/* ── App shell ── */
#app {
    display: flex;
    height: 100vh;
    position: relative;
    z-index: 1;
}

/* ════════════════════════════════════════
   SIDEBAR
════════════════════════════════════════ */
.sidebar {
    width: var(--sidebar-w);
    flex-shrink: 0;
    background: var(--bg-sidebar);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    height: 100vh;
    box-shadow: 2px 0 16px rgba(0,0,0,0.04);
}

/* Header */
.sidebar-header {
    display: flex;
    flex-direction: column;
    gap: 10px;
    padding: 14px 16px;
    border-bottom: 1px solid var(--border);
    flex-shrink: 0;
}

.team-logo {
    width: 100%;
    height: 30px;
    background: var(--accent);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
}

.team-number {
    font-family: var(--f-display);
    font-weight: 800;
    font-size: 13px;
    color: #0a0a0a;
    letter-spacing: 0.04em;
}

.sidebar-header-row {
    display: flex;
    align-items: center;
    gap: 10px;
}

.team-text { flex: 1; min-width: 0; }

.team-name {
    font-family: var(--f-display);
    font-weight: 700;
    font-size: 11px;
    letter-spacing: 0.08em;
    color: var(--text);
    line-height: 1.2;
}

.team-sub {
    font-family: var(--f-mono);
    font-size: 9px;
    color: var(--text-muted);
    letter-spacing: 0.04em;
}

.home-btn {
    background: none;
    border: 1px solid var(--border);
    color: var(--text-muted);
    width: 28px;
    height: 28px;
    border-radius: var(--radius-sm);
    font-size: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    transition: all 0.15s;
}

.home-btn:hover {
    color: var(--accent);
    border-color: var(--accent);
    background: var(--accent-light);
}

/* Lesson list */
.sidebar-lessons {
    flex: 1;
    overflow-y: auto;
    padding: 6px 0;
}

.sidebar-lessons::-webkit-scrollbar { width: 3px; }
.sidebar-lessons::-webkit-scrollbar-track { background: transparent; }
.sidebar-lessons::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 2px;
}

.sidebar-item {
    display: flex;
    align-items: center;
    gap: 9px;
    padding: 7px 16px;
    border: none;
    background: none;
    width: 100%;
    text-align: left;
    border-left: 2px solid transparent;
    transition: all 0.12s;
}

.sidebar-item:hover { background: var(--bg); }

.sidebar-item.active {
    background: var(--accent-light);
    border-left-color: var(--accent);
}

.si-num {
    font-family: var(--f-mono);
    font-size: 10px;
    color: var(--text-dim);
    min-width: 18px;
}

.si-title {
    font-size: 12px;
    color: var(--text-muted);
    flex: 1;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    font-weight: 400;
    transition: color 0.12s;
}

.sidebar-item.active .si-num  { color: var(--accent); }
.sidebar-item.active .si-title { color: var(--text); font-weight: 500; }

.si-dot {
    width: 5px;
    height: 5px;
    border-radius: 50%;
    background: var(--border-strong);
    flex-shrink: 0;
    transition: all 0.15s;
}

.sidebar-item.active .si-dot { background: var(--accent); }

/* Footer / progress */
.sidebar-footer {
    border-top: 1px solid var(--border);
    padding: 14px 16px;
    flex-shrink: 0;
}

.progress-label {
    display: flex;
    justify-content: space-between;
    font-family: var(--f-mono);
    font-size: 9px;
    color: var(--text-muted);
    letter-spacing: 0.08em;
    margin-bottom: 7px;
}

.progress-track {
    height: 3px;
    background: var(--border);
    border-radius: 2px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(to right, var(--accent), #ffa800);
    border-radius: 2px;
    transition: width 0.4s ease;
}

/* ════════════════════════════════════════
   MAIN AREA
════════════════════════════════════════ */
.main {
    flex: 1;
    overflow-y: auto;
    position: relative;
}

.main::-webkit-scrollbar { width: 5px; }
.main::-webkit-scrollbar-track { background: transparent; }
.main::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

/* Views */
.view { min-height: 100vh; animation: fadeUp 0.25s ease; }
.view.hidden { display: none; }

@keyframes fadeUp {
    from { opacity: 0; transform: translateY(6px); }
    to   { opacity: 1; transform: translateY(0); }
}

/* ════════════════════════════════════════
   HOME VIEW — HERO
════════════════════════════════════════ */
.hero {
    min-height: 52vh;
    padding: 64px 64px 48px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    position: relative;
    overflow: hidden;
    border-bottom: 1px solid #222;
    background: #0a0a0a;
}

/* Decorative diagonal stripe */
.hero::after {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 380px;
    height: 100%;
    background: linear-gradient(135deg, transparent 40%, rgba(240, 192, 0, 0.06) 40%);
    pointer-events: none;
}

.hero-grid-deco {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    width: 380px;
    background-image: radial-gradient(circle, rgba(240, 192, 0, 0.45) 1px, transparent 1px);
    background-size: 22px 22px;
    opacity: 0.5;
    pointer-events: none;
    mask-image: linear-gradient(135deg, transparent 40%, black 40%);
    -webkit-mask-image: linear-gradient(135deg, transparent 40%, black 40%);
}

.hero-eyebrow {
    font-family: var(--f-mono);
    font-size: 10px;
    letter-spacing: 0.14em;
    color: var(--accent);
    margin-bottom: 22px;
    display: flex;
    align-items: center;
    gap: 10px;
    position: relative;
    z-index: 1;
}

.hero-eyebrow::before {
    content: '';
    display: inline-block;
    width: 20px;
    height: 2px;
    background: var(--accent);
    border-radius: 1px;
}

.hero-title {
    font-family: var(--f-display);
    font-weight: 800;
    font-size: clamp(42px, 5.5vw, 74px);
    line-height: 0.95;
    letter-spacing: -0.02em;
    display: flex;
    flex-direction: column;
    margin-bottom: 24px;
    position: relative;
    z-index: 1;
}

.ht-line       { color: #ffffff; }
.ht-accent     { color: var(--accent); }

.hero-sub {
    font-family: var(--f-mono);
    font-size: 12px;
    color: rgba(255, 255, 255, 0.45);
    letter-spacing: 0.05em;
    margin-bottom: 36px;
    position: relative;
    z-index: 1;
}

.cta-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: var(--accent);
    color: #0a0a0a;
    font-family: var(--f-display);
    font-weight: 700;
    font-size: 12px;
    letter-spacing: 0.12em;
    padding: 12px 28px;
    border: none;
    border-radius: var(--radius);
    transition: all 0.2s;
    align-self: flex-start;
    position: relative;
    z-index: 1;
    box-shadow: 0 2px 12px var(--accent-glow);
}

.cta-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 24px var(--accent-glow);
}

.cta-btn:active { transform: none; box-shadow: none; }

/* ════════════════════════════════════════
   HOME VIEW — LESSON GRID
════════════════════════════════════════ */
.home-body {
    padding: 40px 64px 64px;
}

.section-label {
    font-family: var(--f-mono);
    font-size: 9px;
    letter-spacing: 0.18em;
    color: var(--text-muted);
    margin-bottom: 18px;
    display: flex;
    align-items: center;
    gap: 14px;
}

.section-label::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--border);
}

.lesson-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(270px, 1fr));
    gap: 12px;
}

.lesson-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px;
    cursor: pointer;
    transition: all 0.18s;
    position: relative;
    overflow: hidden;
}

/* Colored top bar on hover */
.lesson-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 3px;
    background: var(--card-color, var(--accent));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.2s ease;
}

.lesson-card:hover {
    border-color: var(--border-strong);
    box-shadow: 0 4px 20px rgba(0,0,0,0.07);
    transform: translateY(-2px);
}

.lesson-card:hover::before { transform: scaleX(1); }

.card-top {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 10px;
}

.card-week {
    font-family: var(--f-display);
    font-weight: 800;
    font-size: 30px;
    line-height: 1;
    color: var(--border-strong);
    transition: color 0.18s;
}

.lesson-card:hover .card-week { color: var(--text-dim); }

.card-tag {
    font-family: var(--f-mono);
    font-size: 8px;
    font-weight: 500;
    letter-spacing: 0.1em;
    padding: 3px 7px;
    border-radius: var(--radius-sm);
    border: 1px solid;
}

.card-title {
    font-family: var(--f-display);
    font-weight: 600;
    font-size: 14px;
    color: var(--text);
    line-height: 1.3;
    margin-bottom: 12px;
}

.card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.card-count {
    font-family: var(--f-mono);
    font-size: 10px;
    color: var(--text-muted);
}

.card-arrow {
    font-size: 15px;
    color: var(--text-dim);
    transition: all 0.18s;
}

.lesson-card:hover .card-arrow {
    color: var(--accent);
    transform: translateX(4px);
}

/* ════════════════════════════════════════
   LESSON VIEW
════════════════════════════════════════ */
.lesson-topbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 14px 64px;
    border-bottom: 1px solid var(--border);
    background: rgba(245, 245, 243, 0.9);
    backdrop-filter: blur(8px);
    position: sticky;
    top: 0;
    z-index: 5;
}

.back-btn {
    font-family: var(--f-mono);
    font-size: 10px;
    letter-spacing: 0.1em;
    color: var(--text-muted);
    background: none;
    border: 1px solid var(--border);
    padding: 7px 13px;
    border-radius: var(--radius-sm);
    transition: all 0.15s;
}

.back-btn:hover {
    color: var(--accent);
    border-color: var(--accent);
    background: var(--accent-light);
}

.lesson-nav-arrows { display: flex; gap: 8px; }

.nav-arrow {
    font-family: var(--f-mono);
    font-size: 10px;
    letter-spacing: 0.08em;
    color: var(--text-muted);
    background: none;
    border: 1px solid var(--border);
    padding: 7px 13px;
    border-radius: var(--radius-sm);
    transition: all 0.15s;
}

.nav-arrow:hover {
    color: var(--accent);
    border-color: var(--accent);
    background: var(--accent-light);
}

.nav-arrow:disabled {
    opacity: 0.35;
    cursor: not-allowed;
}
.nav-arrow:disabled:hover {
    color: var(--text-muted);
    border-color: var(--border);
    background: none;
}

/* Lesson header */
.lesson-header {
    padding: 48px 64px 36px;
    background: var(--accent);
    border-bottom: 1px solid rgba(0,0,0,0.12);
}

.lesson-meta {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 16px;
}

.lw-badge {
    font-family: var(--f-mono);
    font-size: 10px;
    letter-spacing: 0.14em;
    color: var(--accent);
    background: #0a0a0a;
    border: 1px solid #0a0a0a;
    padding: 4px 10px;
    border-radius: var(--radius-sm);
}

.lt-badge {
    font-family: var(--f-mono);
    font-size: 9px;
    letter-spacing: 0.1em;
    padding: 4px 10px;
    border-radius: var(--radius-sm);
    border: 1px solid;
}

.lesson-title {
    font-family: var(--f-display);
    font-weight: 800;
    font-size: clamp(28px, 4vw, 50px);
    color: #0a0a0a;
    line-height: 1.08;
}

/* Lesson body sections */
.lesson-body {
    padding: 36px 64px 64px;
    display: flex;
    flex-direction: column;
    gap: 20px;
    max-width: 860px;
}

.ls-section {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
}

.ls-header {
    display: flex;
    align-items: center;
    gap: 9px;
    padding: 11px 18px;
    border-bottom: 1px solid var(--border);
    font-family: var(--f-mono);
    font-size: 9px;
    letter-spacing: 0.14em;
    color: var(--text-muted);
    background: var(--bg-card-alt);
}

.accent-dot, .dim-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    flex-shrink: 0;
}
.accent-dot { background: var(--accent); box-shadow: 0 0 5px var(--accent-glow); }
.dim-dot    { background: var(--border-strong); }

.cs-badge {
    margin-left: auto;
    font-size: 8px;
    color: var(--text-dim);
    border: 1px solid var(--border);
    padding: 2px 7px;
    border-radius: 2px;
    letter-spacing: 0.1em;
}

/* Topic list */
.topic-list {
    list-style: none;
    padding: 10px 18px;
}

.topic-list li {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 9px 0;
    font-size: 14px;
    color: var(--text);
    border-bottom: 1px solid rgba(0,0,0,0.04);
    line-height: 1.5;
}

.topic-list li:last-child { border-bottom: none; }

.topic-list li::before {
    content: '';
    width: 5px;
    height: 5px;
    min-width: 5px;
    border-radius: 50%;
    background: var(--accent);
    margin-top: 8px;
}

/* Placeholder sections */
.ls-placeholder { opacity: 0.65; }

.ph-area {
    padding: 22px 18px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.ph-line {
    height: 10px;
    background: var(--border);
    border-radius: 3px;
    width: 100%;
    animation: shimmer 2s ease-in-out infinite;
}
.ph-line.ph-short  { width: 42%; }
.ph-line.ph-med    { width: 68%; }

@keyframes shimmer {
    0%, 100% { opacity: 0.5; }
    50%       { opacity: 0.85; }
}

.ph-code {
    padding: 36px 18px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    color: var(--text-dim);
}

.ph-code-icon {
    font-family: var(--f-mono);
    font-size: 30px;
    color: var(--border-strong);
}

.ph-code-label {
    font-family: var(--f-mono);
    font-size: 11px;
    letter-spacing: 0.04em;
    color: var(--text-muted);
}

/* ════════════════════════════════════════
   LESSON CONTENT RENDERER
════════════════════════════════════════ */

/* Section blocks within a lesson */
.content-section {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
}

.content-section-body {
    padding: 22px 22px 10px;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

/* Text blocks */
.content-text p {
    font-size: 15px;
    color: var(--text);
    line-height: 1.7;
    margin-bottom: 10px;
}

.content-text p:last-child { margin-bottom: 0; }

.content-text strong { font-weight: 600; color: var(--text); }

.content-text code {
    font-family: var(--f-mono);
    font-size: 13px;
    background: var(--bg);
    border: 1px solid var(--border);
    padding: 1px 5px;
    border-radius: 3px;
    color: var(--accent);
}

/* Callout boxes */
.callout {
    border-radius: var(--radius-sm);
    padding: 14px 16px;
    display: flex;
    flex-direction: column;
    gap: 6px;
    border-left: 3px solid;
    font-size: 14px;
    line-height: 1.6;
}

.callout-label {
    font-family: var(--f-mono);
    font-size: 9px;
    font-weight: 600;
    letter-spacing: 0.12em;
}

.callout p { margin: 0; color: var(--text); }

.callout-analogy  { background: #eff6ff; border-color: #3b82f6; }
.callout-analogy .callout-label  { color: #2563eb; }

.callout-warning  { background: #fffbeb; border-color: #f59e0b; }
.callout-warning .callout-label  { color: #b45309; }

.callout-tip      { background: #f0fdf4; border-color: #22c55e; }
.callout-tip .callout-label      { color: #16a34a; }

.callout-info     { background: #f8fafc; border-color: #94a3b8; }
.callout-info .callout-label     { color: #64748b; }

/* Code blocks */
.code-block {
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    overflow: hidden;
    font-size: 13px;
}

.code-block-header {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 7px 14px;
    background: #f0f0ee;
    border-bottom: 1px solid var(--border);
}

.code-lang {
    font-family: var(--f-mono);
    font-size: 9px;
    font-weight: 600;
    letter-spacing: 0.1em;
    color: var(--accent);
    background: var(--accent-light);
    border: 1px solid rgba(224,58,0,0.2);
    padding: 2px 7px;
    border-radius: 2px;
}

.code-label {
    font-family: var(--f-mono);
    font-size: 10px;
    color: var(--text-muted);
}

.code-block pre {
    margin: 0;
    padding: 16px;
    background: #fafafa;
    overflow-x: auto;
    line-height: 1.7;
}

.code-block pre code {
    font-family: var(--f-mono);
    font-size: 13px;
    background: none;
    border: none;
    padding: 0;
    color: var(--text);
}

/* Java syntax highlighting — IntelliJ-like colors */
.hj-kw   { color: #0033b3; font-weight: 600; }
.hj-str  { color: #067d17; }
.hj-com  { color: #8c8c8c; font-style: italic; }
.hj-num  { color: #1750eb; }
.hj-meth { color: #7a3e9d; }

/* File path */
.filepath-block {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 14px;
    background: #fafafa;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
}

.filepath-block code {
    font-family: var(--f-mono);
    font-size: 12px;
    color: var(--text-muted);
    background: none;
    border: none;
    padding: 0;
    word-break: break-all;
}

/* Tables */
.content-table-wrap {
    overflow-x: auto;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border);
}

.content-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 13.5px;
}

.content-table th {
    font-family: var(--f-mono);
    font-size: 9px;
    letter-spacing: 0.1em;
    color: var(--text-muted);
    background: #f5f4f0;
    padding: 9px 14px;
    text-align: left;
    border-bottom: 1px solid var(--border);
    font-weight: 600;
}

.content-table td {
    padding: 10px 14px;
    border-bottom: 1px solid #f0eeea;
    color: var(--text);
    vertical-align: top;
    line-height: 1.5;
}

.content-table tr:last-child td { border-bottom: none; }

.content-table td code {
    font-family: var(--f-mono);
    font-size: 12px;
    background: var(--bg);
    border: 1px solid var(--border);
    padding: 1px 5px;
    border-radius: 3px;
}

.type-name { color: #0033b3 !important; font-weight: 600 !important; }

.usage-col { color: var(--text-muted); font-size: 12.5px; }

/* ── Quiz ── */
.quiz-section {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
}

.quiz-score {
    margin-left: auto;
    font-family: var(--f-mono);
    font-size: 10px;
    color: var(--accent);
    background: var(--accent-light);
    border: 1px solid var(--accent-border);
    padding: 2px 9px;
    border-radius: 10px;
}

.quiz-body {
    padding: 18px 20px;
    display: flex;
    flex-direction: column;
    gap: 28px;
}

.quiz-question {}

.quiz-q-text {
    font-size: 15px;
    color: var(--text);
    font-weight: 500;
    line-height: 1.5;
    margin-bottom: 12px;
    display: flex;
    gap: 10px;
    align-items: baseline;
}

.quiz-q-num {
    font-family: var(--f-mono);
    font-size: 10px;
    font-weight: 600;
    color: var(--accent);
    background: var(--accent-light);
    border: 1px solid var(--accent-border);
    padding: 2px 7px;
    border-radius: var(--radius-sm);
    flex-shrink: 0;
    letter-spacing: 0.05em;
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 7px;
}

.quiz-option {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 14px;
    background: var(--bg-card-alt);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    text-align: left;
    font-size: 14px;
    color: var(--text);
    cursor: pointer;
    transition: all 0.15s;
    font-family: inherit;
}

.quiz-option:hover:not(:disabled) {
    border-color: var(--accent);
    background: var(--accent-light);
}

.quiz-opt-letter {
    font-family: var(--f-mono);
    font-size: 10px;
    font-weight: 600;
    color: var(--text-muted);
    min-width: 18px;
    text-align: center;
}

.quiz-option.correct {
    background: #f0fdf4;
    border-color: #16a34a;
    color: #166534;
}

.quiz-option.correct .quiz-opt-letter { color: #16a34a; }

.quiz-option.wrong {
    background: #fff1f2;
    border-color: #f43f5e;
    color: #9f1239;
}

.quiz-option.wrong .quiz-opt-letter { color: #f43f5e; }

.quiz-option:disabled { cursor: not-allowed; }

.quiz-explanation {
    margin-top: 10px;
    padding: 10px 14px;
    background: #f8fafc;
    border: 1px solid var(--border);
    border-left: 3px solid var(--blue);
    border-radius: var(--radius-sm);
    font-size: 13.5px;
    color: var(--text-muted);
    line-height: 1.6;
}

.quiz-explanation.hidden { display: none; }

/* ── Complete button ── */
.complete-wrap {
    display: flex;
    justify-content: flex-end;
    padding-top: 8px;
}

.complete-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: none;
    border: 1.5px solid var(--border-strong);
    color: var(--text-muted);
    font-family: var(--f-display);
    font-weight: 700;
    font-size: 11px;
    letter-spacing: 0.1em;
    padding: 11px 24px;
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.2s;
}

.complete-btn:hover {
    background: #f0fdf4;
    border-color: #16a34a;
    color: #16a34a;
}

.complete-btn.done {
    background: #f0fdf4;
    border-color: #16a34a;
    color: #16a34a;
    cursor: default;
}

/* Sidebar done dot */
.si-dot.done { background: #16a34a !important; box-shadow: none !important; }

/* ════════════════════════════════════════
   MOBILE
════════════════════════════════════════ */

/* Hamburger button — hidden on desktop */
.menu-btn {
    display: none;
}

/* Sidebar overlay — hidden by default */
.sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.4);
    z-index: 99;
    backdrop-filter: blur(2px);
}

.sidebar-overlay.show { display: block; }

@media (max-width: 720px) {

    /* Sidebar slides off-canvas */
    .sidebar {
        position: fixed;
        top: 0;
        left: 0;
        height: 100vh;
        z-index: 100;
        transform: translateX(-100%);
        transition: transform 0.25s ease;
        box-shadow: 4px 0 24px rgba(0,0,0,0.12);
    }

    .sidebar.open { transform: translateX(0); }

    /* Main takes full width */
    .main { width: 100%; }

    /* Hamburger button — visible on mobile */
    .menu-btn {
        display: flex;
        align-items: center;
        justify-content: center;
        position: fixed;
        bottom: 24px;
        right: 20px;
        width: 48px;
        height: 48px;
        background: var(--accent);
        color: #0a0a0a;
        border: none;
        border-radius: 50%;
        font-size: 20px;
        box-shadow: 0 4px 16px rgba(0,0,0,0.18);
        z-index: 101;
        cursor: pointer;
        transition: transform 0.15s;
    }

    .menu-btn:active { transform: scale(0.92); }

    /* Hero */
    .hero { padding: 40px 24px 32px; min-height: auto; }
    .hero-title { font-size: clamp(36px, 12vw, 56px); }
    .hero::after, .hero-grid-deco { display: none; }

    /* Home body */
    .home-body { padding: 28px 20px 80px; }
    .lesson-grid { grid-template-columns: 1fr 1fr; gap: 10px; }
    .card-title { font-size: 12px; }
    .card-week  { font-size: 22px; }

    /* Lesson topbar */
    .lesson-topbar { padding: 10px 16px; }
    .lesson-nav-arrows { gap: 6px; }
    .nav-arrow, .back-btn { padding: 6px 10px; font-size: 9px; }

    /* Lesson header + body */
    .lesson-header { padding: 28px 20px 24px; }
    .lesson-body   { padding: 20px 16px 80px; }

    /* Sections */
    .content-section-body { padding: 16px 14px 8px; }
    .ls-header { padding: 10px 14px; }
    .topic-list { padding: 6px 14px; }
    .topic-list li { font-size: 13px; }
    .quiz-body { padding: 14px 14px; }
    .ph-area, .ph-code { padding: 16px 14px; }

    /* Code blocks */
    .code-block pre { padding: 12px; font-size: 12px; overflow-x: auto; }

    /* Tables */
    .content-table td, .content-table th { padding: 8px 10px; font-size: 12px; }
    .usage-col { display: none; }

    /* Complete button */
    .complete-wrap { padding-top: 4px; }
}