/* === NAVBAR EMERGENCY FIX === */
.topnav { display: flex !important; flex-direction: row !important; flex-wrap: nowrap !important; align-items: center !important; background-color: #2C1810; overflow: visible !important; }
.topnav > * { flex-shrink: 0; }
.dropdown-content, .nav-dropdown-menu { display: none !important; position: absolute !important; z-index: 9999; }
.dropdown:hover > .dropdown-content, .dropdown:hover > .nav-dropdown-menu { display: block !important; }
.nav-dropdown:hover .nav-dropdown-menu { display: block !important; }
/* === END FIX === */

/* ════════════════════════════════════════════════════════════
   DevLearn — Design System
   ════════════════════════════════════════════════════════════ */
:root {
    /* 色彩系統 — 科技灰黑色 Dark Theme */
    --bg:       #0f1117;
    --bg2:      #1a1d27;
    --bg3:      #242836;
    --bg4:      #2d3348;
    --border:   #2d3348;
    --border2:  #3d4460;

    /* 文字 */
    --text:      #e2e8f0;
    --text-muted:#94a3b8;
    --text-dim:  #64748b;

    /* 主色 — Teal Green */
    --accent:   #00b894;
    --accent2:  #00cec9;
    --accent3:  #009688;
    --yellow:   #ffd600;
    --orange:   #f97316;
    --success:  #00c853;
    --warning:  #ffd600;
    --danger:   #ff1744;
    --card-bg:  rgba(26, 29, 39, 0.9);
    --card-border: rgba(0, 184, 148, 0.1);
    --card-shadow: 0 4px 20px rgba(0,0,0,0.3);

    /* 分類顏色 */
    --cat-csharp:   #9B59B6;
    --cat-aspnet:   #3498DB;
    --cat-db:       #E74C3C;
    --cat-net:      #27AE60;
    --cat-sec:      #F39C12;
    --cat-docker:   #1ABC9C;
    --cat-frontend: #E91E63;
    --cat-git:      #F57C00;
    --cat-server:   #00897B;
    --cat-aimodel:  #7C4DFF;
    --cat-claude:   #00BCD4;
    --cat-project:  #4CAF50;
    --cat-interview:#FF5722;

    --sidebar-w: 290px;
    --marquee-h: 30px;
    --topnav-h:  56px;
    --radius:    10px;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
    --font-sans: 'Noto Sans TC', 'Inter', sans-serif;
    --shadow:    0 2px 12px rgba(0,0,0,.08);
    --glow:      none;

    /* 微動畫 */
    --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
    --transition: .2s var(--ease-out);
}

/* Light mode */
[data-theme="light"] {
    --bg: #f5f5f5;
    --bg2: #ffffff;
    --bg3: #e8e8e8;
    --accent: #00896b;
    --accent2: #4f46e5;
    --text: #1a1a2e;
    --text-muted: #555555;
    --border: #d0d0d0;
    --card-bg: rgba(255,255,255,0.9);
    --card-border: rgba(0,0,0,0.08);
    --card-shadow: 0 2px 10px rgba(0,0,0,0.08);
}

[data-theme="light"] .topnav {
    background: rgba(255,255,255,0.95) !important;
    border-bottom-color: #e0e0e0 !important;
}

[data-theme="light"] .topnav a,
[data-theme="light"] .topnav .logo {
    color: #1a1a2e !important;
}

[data-theme="light"] .hero {
    background: linear-gradient(135deg, #00b894, #6366f1) !important;
}

/* ── Reset ─────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; scroll-padding-top: calc(var(--topnav-h) + var(--marquee-h) + 16px); }
body {
    background: var(--bg);
    color: var(--text);
    font-family: var(--font-sans);
    font-size: 0.95rem;
    line-height: 1.6;
    min-height: 100vh;
    padding-top: calc(var(--topnav-h) + var(--marquee-h));
}
/* 微動畫：頁面載入淡入 */
@keyframes fadeIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }
.home-layout, .chapter-layout { animation: fadeIn .35s var(--ease-out); }

/* 所有可互動元素加上平滑 transition */
button, a, input, .category-card, .path-node, .challenge-btn, .nav-item {
    transition: all var(--transition);
}

a { color: var(--accent); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--accent2); }

/* ── Scrollbar ──────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--bg2); }
::-webkit-scrollbar-thumb { background: var(--bg4); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--accent); }

/* ════════════════════════════════════════════════════════════
   TOP NAV
   ════════════════════════════════════════════════════════════ */
.topnav {
    position: fixed; top: var(--marquee-h); left: 0; right: 0; z-index: 1003;
    height: var(--topnav-h);
    background: rgba(15, 17, 23, 0.95);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    box-shadow: none;
    display: flex !important; flex-direction: row !important; flex-wrap: nowrap !important;
    align-items: center; gap: 1.2rem; padding: 0 1.8rem;
}
.logo {
    font-weight: 800;
    font-size: 1.05rem;
    color: var(--text);
    white-space: nowrap;
    display: flex;
    align-items: center;
    gap: .5rem;
    letter-spacing: -.02em;
}
.logo { color: #e2e8f0 !important; }
.topnav .logo span { color: #e2e8f0 !important; }
.nav-search input { background: var(--bg3); border-color: var(--border); color: var(--text); }
.nav-search input::placeholder { color: var(--text-dim); }
.nav-search input:focus { border-color: var(--accent); box-shadow: none; }
.nav-scores-link { color: #94a3b8 !important; border-color: var(--border) !important; }
.nav-scores-link:hover { color: var(--accent) !important; border-color: var(--accent) !important; background: rgba(0,184,148,.08) !important; }
.progress-badge { background: var(--bg3); border-color: var(--border); color: var(--accent); }

.nav-search { flex: 1; max-width: 380px; position: relative; }
.nav-search input {
    width: 100%;
    background: var(--bg3);
    border: 1px solid var(--border);
    color: var(--text);
    border-radius: 8px;
    padding: 7px 14px 7px 36px;
    font-size: .84rem;
    font-family: var(--font-sans);
    transition: border-color .2s, box-shadow .2s;
}
.nav-search::before {
    content: '🔍';
    position: absolute;
    left: 10px;
    top: 50%;
    transform: translateY(-50%);
    font-size: .8rem;
    pointer-events: none;
}
.nav-search input:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 2px rgba(91,164,207,.15);
}
.search-dropdown {
    position: absolute; top: calc(100% + 6px); left: 0; right: 0;
    background: var(--bg3);
    border: 1px solid var(--border2);
    border-radius: 10px;
    z-index: 300;
    max-height: 320px;
    overflow-y: auto;
    box-shadow: var(--shadow);
}
.search-item {
    display: flex; align-items: center; gap: 10px;
    padding: 11px 16px;
    cursor: pointer;
    font-size: .84rem;
    border-bottom: 1px solid var(--border);
    transition: background .15s;
}
.search-item:last-child { border-bottom: none; }
.search-item:hover { background: var(--bg4); }
.search-item-cat { font-size: .7rem; color: var(--text-dim); margin-left: auto; }

.nav-right { margin-left: auto; display: flex; align-items: center; gap: 1rem; }
.nav-scores-link {
    font-size: .82rem;
    color: var(--text-muted);
    padding: 5px 12px;
    border: 1px solid var(--border);
    border-radius: 6px;
    transition: all .2s;
}
.nav-scores-link:hover { border-color: var(--accent2); color: var(--accent2); }

/* Navbar Dropdown */
.nav-dropdown { position: relative; }
.nav-dropdown-btn { cursor: pointer; background: none; }
.nav-dropdown-menu {
    display: none !important; position: absolute; top: 100%; left: 50%; transform: translateX(-50%);
    background: var(--bg2); border: 1px solid var(--border); border-radius: 10px;
    padding: 6px 0; min-width: 160px; box-shadow: 0 8px 30px rgba(0,0,0,.12);
    z-index: 1000;
}
.nav-dropdown:hover .nav-dropdown-menu { display: block !important; }
.nav-dropdown-menu a {
    display: block; padding: 8px 16px; color: var(--text); font-size: .85rem;
    text-decoration: none; transition: background .2s;
}
.nav-dropdown-menu a:hover { background: var(--bg3); color: var(--accent2); }

.progress-badge {
    background: var(--bg3);
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 5px 12px;
    font-size: .78rem;
    color: var(--accent);
    font-weight: 600;
    white-space: nowrap;
}

/* ════════════════════════════════════════════════════════════
   HOME PAGE
   ════════════════════════════════════════════════════════════ */
.home-layout { }

/* ── Hero ────────────────────────────────────────────────── */
.hero {
    position: relative;
    min-height: 380px;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 4rem 2rem;
    overflow: hidden;
    background: linear-gradient(135deg, rgba(0,184,148,0.85), rgba(9,132,227,0.85)), url('/images/hero-coding.jpg') center/cover;
    border-bottom: none;
}
.hero-bg {
    position: absolute; inset: 0;
    background: none;
}
.hero-bg::after {
    content: '';
    position: absolute; inset: 0;
    background-image: radial-gradient(circle at 1px 1px, rgba(255,255,255,.08) 1px, transparent 1px);
    background-size: 32px 32px;
}
.hero h1, .hero p, .hero-desc { color: #fff !important; }
.hero h1 .highlight { color: #fff !important; text-shadow: 0 2px 8px rgba(0,0,0,0.15); }
.hero-badge { background: rgba(255,255,255,.2); border-color: rgba(255,255,255,.3); color: #fff; }
.stat-num { color: #fff !important; }
.stat-num.clr-1 { color: #fff !important; }
.stat-num.clr-2 { color: #fff !important; }
.stat-num.clr-3 { color: #fff !important; }
.stat small { color: rgba(255,255,255,.85) !important; }
.hero-content { position: relative; z-index: 1; max-width: 700px; }
.hero-badge {
    display: inline-block;
    background: rgba(255,255,255,.2);
    border: 1px solid rgba(255,255,255,.3);
    color: #fff;
    border-radius: 20px;
    padding: 6px 18px;
    font-size: .75rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    letter-spacing: .06em;
}
.hero h1 {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 1rem;
    line-height: 1.2;
    letter-spacing: -.02em;
}
.hero h1 .highlight {
    color: var(--accent);
}
.hero p {
    font-size: 1.05rem;
    color: var(--text-muted);
    line-height: 1.8;
    margin-bottom: 2.5rem;
    max-width: 540px;
    margin-left: auto;
    margin-right: auto;
}
.hero-cta { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; margin-bottom: 3rem; }
.btn-cta-primary {
    background: #fff;
    color: var(--accent);
    border: none;
    border-radius: 24px;
    padding: 12px 32px;
    font-size: .9rem;
    font-weight: 700;
    cursor: pointer;
    text-decoration: none;
    transition: background 0.2s, transform 0.1s;
    font-family: var(--font-sans);
    box-shadow: 0 2px 8px rgba(0,0,0,.1);
}
.btn-cta-primary:hover { background: #f0f0f0; transform: translateY(-1px); color: var(--accent3); text-decoration:none; }
.btn-cta-secondary {
    background: transparent;
    color: #fff;
    border: 2px solid rgba(255,255,255,.5);
    border-radius: 24px;
    padding: 10px 28px;
    font-size: .9rem;
    font-weight: 600;
    cursor: pointer;
    text-decoration: none;
    transition: all .2s;
}
.btn-cta-secondary:hover { border-color: #fff; color: #fff; transform: translateY(-1px); text-decoration:none; background: rgba(255,255,255,.1); }

.hero-stats { display: flex; justify-content: center; gap: 2rem; }
.stat {
    text-align: center;
    background: rgba(255,255,255,.2);
    border-radius: 16px;
    padding: 12px 24px;
    backdrop-filter: blur(4px);
}
.stat-num { font-size: 2.4rem; font-weight: 800; display: block; line-height: 1; }
.stat-num.clr-1 { color: #fff; }
.stat-num.clr-2 { color: #fff; }
.stat-num.clr-3 { color: #fff; }
.stat small { color: rgba(255,255,255,.85); font-size: .78rem; margin-top: .3rem; display: block; }

/* ── Categories Grid ─────────────────────────────────────── */
.courses-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
    gap: 1.5rem;
    padding: 2.5rem 2rem;
    max-width: 1400px;
    margin: 0 auto;
}
.category-card {
    background: var(--bg2);
    border: 1px solid var(--card-border);
    border-radius: 16px;
    overflow: hidden;
    transition: transform 0.2s, border-color 0.3s, box-shadow 0.3s;
    position: relative;
    box-shadow: var(--card-shadow);
}
.category-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 0;
    background: none;
}
.category-card:hover {
    transform: translateY(-2px);
    border-color: var(--accent);
    box-shadow: 0 4px 20px rgba(0,0,0,0.12);
}
.category-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1.3rem 1.5rem;
    background: var(--bg3);
    border-bottom: 1px solid var(--border);
}
.cat-icon-wrap {
    width: 44px; height: 44px;
    background: var(--bg3);
    border: 1px solid var(--border);
    border-radius: 10px;
    display: flex; align-items: center; justify-content: center;
    font-size: 1.4rem;
    flex-shrink: 0;
}
.category-header h2 { font-size: .95rem; color: var(--text); margin-bottom: 2px; }
.category-header small { color: var(--text-muted); font-size: .73rem; }
.dl-all-btn {
    margin-left: auto;
    background: var(--bg4);
    border: 1px solid var(--border2);
    border-radius: 7px;
    padding: 5px 11px;
    font-size: .75rem;
    color: var(--text-muted);
    white-space: nowrap;
    transition: all .2s;
    flex-shrink: 0;
}
.dl-all-btn:hover { background: var(--bg3); color: var(--accent2); border-color: var(--accent2); text-decoration: none; }

.chapter-list { list-style: none; padding: .4rem 0; }
.chapter-link {
    display: flex;
    align-items: center;
    gap: .7rem;
    padding: 10px 1.5rem;
    color: var(--text-muted);
    transition: all .18s;
    font-size: .875rem;
}
.chapter-link:hover { background: var(--bg3); color: var(--text); text-decoration: none; }
.ch-icon { font-size: .95rem; width: 22px; flex-shrink: 0; }
.ch-title { flex: 1; }
.ch-arrow { color: var(--border2); font-size: .8rem; transition: transform .2s; }
.chapter-link:hover .ch-arrow { transform: translateX(3px); color: var(--accent); }

/* Badges */
.badge {
    font-size: .65rem;
    padding: 2px 8px;
    border-radius: 4px;
    font-weight: 700;
    letter-spacing: .04em;
    text-transform: uppercase;
}
.badge-green  { background: rgba(34,197,94,.1); color: #22c55e; border: 1px solid rgba(34,197,94,.2); }
.badge-blue   { background: rgba(99,102,241,.1); color: #818cf8; border: 1px solid rgba(99,102,241,.2); }
.badge-red    { background: rgba(239,68,68,.1); color: #ef4444; border: 1px solid rgba(239,68,68,.2); }

/* ── Section Blocks ──────────────────────────────────────── */
.section-block {
    max-width: 1400px;
    margin: 0 auto;
    padding: 3rem 2rem 1rem;
}
.section-header {
    text-align: center;
    margin-bottom: 2.5rem;
}
.section-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text);
    margin-bottom: .5rem;
    letter-spacing: -.02em;
}
.title-icon { margin-right: .4rem; }
.section-subtitle {
    color: var(--text-muted);
    font-size: .92rem;
}

/* ── Learning Path (視覺化學習路徑) ─────────────────────── */
.learning-path {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: .6rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
    padding: 2rem 0;
}
.path-node {
    background: var(--bg2);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 1.8rem 1.5rem;
    text-align: center;
    width: 240px;
    position: relative;
    transition: all .3s;
    overflow: hidden;
    box-shadow: var(--card-shadow);
}
.path-node::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 4px;
    background: var(--node-color, var(--accent));
    border-radius: 16px 16px 0 0;
}
.path-node:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 24px rgba(0,0,0,.1);
    border-color: var(--node-color, var(--accent));
}
.path-step-num {
    display: inline-block;
    font-size: .65rem;
    font-weight: 800;
    letter-spacing: .15em;
    color: var(--node-color, var(--accent));
    background: rgba(0,184,148,.06);
    border: 1px solid rgba(0,184,148,.15);
    border-radius: 4px;
    padding: 2px 10px;
    margin-bottom: 1rem;
}
.path-icon { font-size: 2.2rem; margin-bottom: .8rem; }
.path-node h3 { font-size: .95rem; margin-bottom: .4rem; }
.path-desc { font-size: .78rem; color: var(--text-muted); margin-bottom: 1rem; line-height: 1.5; }
.path-meta { font-size: .7rem; color: var(--text-dim); margin-bottom: .8rem; }
.path-start-btn {
    display: inline-block;
    padding: 6px 18px;
    border: 1px solid var(--node-color, var(--accent));
    border-radius: 8px;
    font-size: .8rem;
    color: var(--node-color, var(--accent));
    font-weight: 600;
    transition: all .2s;
}
.path-start-btn:hover {
    background: var(--node-color, var(--accent));
    color: var(--bg);
    text-decoration: none;
}
.path-arrow {
    color: var(--text-dim);
    flex-shrink: 0;
    animation: arrowPulse 2s ease-in-out infinite;
}
@keyframes arrowPulse {
    0%, 100% { opacity: .4; transform: translateX(0); }
    50% { opacity: 1; transform: translateX(4px); }
}

/* ── Core Cards ─────────────────────────────────────────── */
.core-cards {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
    gap: 1.5rem;
}

/* ── Quick Challenge ────────────────────────────────────── */
.challenge-box {
    max-width: 700px;
    margin: 0 auto;
}
.challenge-options {
    display: flex;
    gap: 1.2rem;
    justify-content: center;
    flex-wrap: wrap;
}
.challenge-btn {
    display: flex;
    align-items: center;
    gap: 1rem;
    background: var(--bg2);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 1.2rem 2rem;
    cursor: pointer;
    transition: all .25s;
    color: var(--text);
    font-family: var(--font-sans);
    min-width: 180px;
    box-shadow: var(--card-shadow);
}
.challenge-btn:hover {
    border-color: var(--accent);
    transform: translateY(-2px);
}
.cb-num {
    font-size: 2rem;
    font-weight: 800;
    color: var(--accent);
    line-height: 1;
}
.cb-label {
    text-align: left;
    font-size: .88rem;
    font-weight: 600;
}
.cb-label small {
    font-weight: 400;
    color: var(--text-muted);
    font-size: .75rem;
}

/* ── Hero extra btn ─────────────────────────────────────── */
.btn-cta-ghost {
    color: rgba(255,255,255,.9);
    border: 1px solid rgba(255,255,255,.3);
    border-radius: 24px;
    padding: 12px 28px;
    font-size: .95rem;
    font-weight: 600;
    transition: all .2s;
}
.btn-cta-ghost:hover { border-color: #fff; color: #fff; text-decoration: none; background: rgba(255,255,255,.1); }

/* ── Quiz Modal ─────────────────────────────────────────── */
.quiz-modal {
    position: fixed; inset: 0; z-index: 999;
    background: rgba(0,0,0,.7);
    backdrop-filter: blur(8px);
    display: flex; align-items: center; justify-content: center;
    padding: 2rem;
}
.quiz-modal-inner {
    background: var(--bg2);
    border: 1px solid var(--border);
    border-radius: 16px;
    max-width: 700px;
    width: 100%;
    max-height: 85vh;
    overflow-y: auto;
    padding: 2rem;
    position: relative;
}
.quiz-close {
    position: absolute; top: 12px; right: 16px;
    background: none; border: none; color: var(--text-muted);
    font-size: 1.3rem; cursor: pointer;
}
.quiz-close:hover { color: var(--accent3); }
.quiz-title { font-size: 1.2rem; margin-bottom: 1.5rem; text-align: center; }
.quiz-q {
    background: var(--bg3);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 1.2rem;
    margin-bottom: 1rem;
}
.quiz-q-num {
    font-size: .7rem; font-weight: 800; color: var(--accent2);
    letter-spacing: .1em; margin-bottom: .4rem;
}
.quiz-q-text { margin-bottom: .8rem; font-size: .9rem; line-height: 1.6; }
.quiz-option {
    display: flex; align-items: flex-start; gap: .6rem;
    padding: 8px 10px; margin-bottom: 4px;
    border-radius: 6px; cursor: pointer;
    font-size: .85rem; color: var(--text-muted);
    transition: background .15s;
}
.quiz-option:hover { background: var(--bg4); }
.quiz-option input { margin-top: 3px; }
.quiz-input {
    width: 100%; padding: 8px 12px;
    background: var(--bg4); border: 1px solid var(--border);
    border-radius: 6px; color: var(--text);
    font-family: var(--font-mono); font-size: .85rem;
}
.quiz-input:focus { outline: none; border-color: var(--accent); }
.quiz-submit-btn {
    display: block; width: 100%; padding: 12px;
    background: var(--accent);
    color: #fff; border: none; border-radius: 8px;
    font-size: .92rem; font-weight: 700; cursor: pointer;
    margin-top: 1rem; font-family: var(--font-sans);
    transition: all var(--transition);
}
.quiz-submit-btn:hover { background: var(--accent3); transform: translateY(-1px); }

/* Quiz Result */
.quiz-result { text-align: center; margin-bottom: 1.5rem; }
.result-circle {
    width: 100px; height: 100px;
    border-radius: 50%;
    border: 4px solid var(--accent);
    display: flex; align-items: center; justify-content: center;
    margin: 0 auto 1rem;
    font-size: 1.4rem; font-weight: 800;
    background: conic-gradient(var(--accent) var(--pct), transparent var(--pct));
    position: relative;
}
.result-circle span {
    background: var(--bg2);
    border-radius: 50%;
    width: 84px; height: 84px;
    display: flex; align-items: center; justify-content: center;
}
.result-grade { font-size: 1.1rem; font-weight: 700; }
.quiz-detail {
    padding: 1rem; margin-bottom: .6rem;
    border-radius: 8px; font-size: .84rem;
    border-left: 4px solid var(--border);
}
.quiz-detail.correct { border-left-color: var(--success); background: rgba(34,197,94,.04); }
.quiz-detail.wrong { border-left-color: var(--danger); background: rgba(239,68,68,.04); }
.qd-head { font-weight: 600; margin-bottom: .4rem; }
.qd-ans, .qd-correct { font-size: .8rem; color: var(--text-muted); margin-bottom: .2rem; }
.qd-ans code, .qd-correct code { background: var(--bg4); padding: 1px 6px; border-radius: 3px; }
.qd-explain { font-size: .8rem; color: var(--text-muted); margin-top: .4rem; }

/* ── Locked/Unlock styles ───────────────────────────────── */
.nav-item.locked {
    opacity: .4;
    cursor: not-allowed;
    pointer-events: none;
}
.nav-item.locked .nav-check { color: var(--text-dim); }

.locked-banner {
    text-align: center;
    padding: 5rem 2rem;
    color: var(--text-muted);
}
.locked-icon { font-size: 4rem; margin-bottom: 1rem; }
.locked-banner h2 { color: var(--text); margin-bottom: .5rem; }

.best-score {
    font-size: .7rem;
    padding: 2px 8px;
    border-radius: 4px;
    font-weight: 700;
}
.best-score.passed { background: rgba(34,197,94,.1); color: var(--success); border: 1px solid rgba(34,197,94,.2); }
.best-score.failed { background: rgba(239,68,68,.1); color: var(--danger); border: 1px solid rgba(239,68,68,.2); }

.nav-locked {
    opacity: .5;
    cursor: not-allowed;
}

/* ── Score Toast ─────────────────────────────────────────── */
.score-toast {
    position: fixed;
    top: calc(var(--topnav-h) + 12px);
    right: 20px;
    z-index: 500;
    transition: all .4s ease;
}
.score-toast.hidden { opacity: 0; transform: translateY(-20px); pointer-events: none; }
.score-toast:not(.hidden) { opacity: 1; transform: translateY(0); }
.toast-content {
    background: var(--bg3);
    border: 1px solid var(--border2);
    color: var(--text);
    padding: 12px 20px;
    border-radius: 8px;
    font-size: .88rem;
    font-weight: 600;
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: 8px;
}
.toast-icon { font-size: 1.2rem; }

/* ════════════════════════════════════════════════════════════
   CHAPTER PAGE — Sidebar + Main
   ════════════════════════════════════════════════════════════ */
.chapter-layout {
    display: flex;
    min-height: 100vh;
}

/* ── Sidebar ─────────────────────────────────────────────── */
.sidebar {
    width: var(--sidebar-w);
    flex-shrink: 0;
    background: var(--bg2);
    border-right: 1px solid var(--border);
    position: fixed;
    top: var(--topnav-h);
    bottom: 0;
    left: 0;
    overflow-y: auto;
    z-index: 50;
}
.sidebar-header {
    padding: 1rem;
    border-bottom: 1px solid var(--border);
    background: var(--bg2);
    position: sticky;
    top: 0;
    z-index: 10;
}
.back-home {
    font-size: .78rem;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    gap: .4rem;
    margin-bottom: .7rem;
    transition: color .2s;
}
.back-home:hover { color: var(--accent); text-decoration: none; }
.sidebar-search input {
    width: 100%;
    background: var(--bg3);
    border: 1px solid var(--border);
    color: var(--text);
    border-radius: 7px;
    padding: 7px 11px;
    font-size: .8rem;
    font-family: var(--font-sans);
}
.sidebar-search input:focus { outline: none; border-color: var(--accent); }

.sidebar-nav { padding: .3rem 0; }
.nav-group { border-bottom: 1px solid var(--border); }
.nav-group-toggle {
    width: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 1rem;
    background: none;
    border: none;
    color: var(--text-dim);
    font-size: .72rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: .08em;
    cursor: pointer;
    font-family: var(--font-sans);
    transition: color .2s, background .2s;
}
.nav-group-toggle:hover { color: var(--text-muted); background: var(--bg3); }
.toggle-icon { font-size: .65rem; transition: transform .2s; }
.nav-group:not(.open) .toggle-icon { transform: rotate(-90deg); }
.nav-group-items { display: none; list-style: none; }
.nav-group.open .nav-group-items { display: block; }

.nav-item {
    display: flex;
    align-items: center;
    gap: .5rem;
    padding: 8px .8rem 8px 1.4rem;
    color: var(--text-dim);
    font-size: .81rem;
    transition: all .15s;
    border-left: 3px solid transparent;
}
.nav-item:hover { color: var(--text-muted); background: var(--bg3); text-decoration: none; }
.nav-item.active {
    color: var(--accent);
    background: rgba(99,102,241,.08);
    border-left-color: var(--accent);
}
.nav-item.done .nav-check { color: var(--accent); }
.nav-check { width: 16px; flex-shrink: 0; font-size: .7rem; }
.nav-title { flex: 1; }

/* ── Chapter Main ────────────────────────────────────────── */
.chapter-main {
    flex: 1;
    margin-left: var(--sidebar-w);
    max-width: 860px;
    padding: 2rem 2.5rem;
}
.chapter-toolbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: .8rem;
    margin-bottom: 2rem;
    padding-bottom: 1.2rem;
    border-bottom: 1px solid var(--border);
}
.chapter-meta { display: flex; gap: .5rem; align-items: center; }
.chapter-cat {
    background: var(--bg3);
    border: 1px solid var(--border2);
    border-radius: 5px;
    padding: 3px 10px;
    font-size: .72rem;
    color: var(--text-muted);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: .05em;
}
.chapter-level { border-radius: 5px; padding: 3px 10px; font-size: .72rem; font-weight: 700; }
.level-beginner    { background: rgba(34,197,94,.1); color: var(--success); }
.level-intermediate{ background: rgba(99,102,241,.1); color: var(--accent2); }
.level-advanced    { background: rgba(239,68,68,.1); color: var(--danger); }

.toolbar-actions { display: flex; gap: .5rem; flex-wrap: wrap; }
.btn-tool {
    background: var(--bg3);
    border: 1px solid var(--border);
    color: var(--text-muted);
    border-radius: 7px;
    padding: 7px 14px;
    font-size: .78rem;
    cursor: pointer;
    font-family: var(--font-sans);
    transition: all .2s;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: .3rem;
}
.btn-tool:hover { border-color: var(--border2); color: var(--text); background: var(--bg4); text-decoration: none; }
.btn-quiz  { border-color: rgba(255,215,0,.4); color: var(--yellow); }
.btn-quiz:hover  { background: rgba(255,215,0,.08); border-color: var(--yellow); }
.btn-done.is-done { border-color: rgba(34,197,94,.4); color: var(--success); background: rgba(34,197,94,.06); }

/* ── Markdown Content ────────────────────────────────────── */
.chapter-content {
    line-height: 1.85;
    font-size: .95rem;
    color: var(--text-muted);
}
.chapter-content h1 {
    font-size: 2rem;
    font-weight: 800;
    color: var(--text);
    margin: 0 0 1.5rem;
    padding-bottom: .8rem;
    border-bottom: 2px solid var(--border);
    letter-spacing: -.02em;
}
.chapter-content h2 {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--accent);
    margin: 2.5rem 0 .9rem;
    padding-left: 1rem;
    border-left: 3px solid var(--accent);
}
.chapter-content h3 {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text);
    margin: 1.8rem 0 .6rem;
}
.chapter-content h4 {
    font-size: .95rem;
    color: var(--orange);
    margin: 1.2rem 0 .4rem;
    font-weight: 600;
}
.chapter-content p { margin-bottom: 1.1rem; }
.chapter-content strong { color: var(--text); font-weight: 600; }
.chapter-content em { color: var(--yellow); font-style: normal; }

/* Code blocks */
.chapter-content pre {
    background: #070B14 !important;
    border: 1px solid var(--border);
    border-radius: 10px;
    overflow-x: auto;
    margin: 1.2rem 0;
    position: relative;
}
.chapter-content pre::before {
    content: '';
    display: block;
    height: 32px;
    background: var(--bg3);
    border-bottom: 1px solid var(--border);
    border-radius: 10px 10px 0 0;
    background-image: radial-gradient(circle, #ff6058 6px, transparent 6px),
                      radial-gradient(circle, #ffbd2e 6px, transparent 6px),
                      radial-gradient(circle, #28c840 6px, transparent 6px);
    background-repeat: no-repeat;
    background-size: 12px 12px, 12px 12px, 12px 12px;
    background-position: 14px center, 32px center, 50px center;
}
.chapter-content pre code {
    font-family: var(--font-mono) !important;
    font-size: .82rem !important;
    line-height: 1.7 !important;
    display: block;
    padding: 1rem 1.2rem !important;
}
.chapter-content code:not(pre code) {
    background: rgba(99,102,241,.08);
    color: var(--accent2);
    border: 1px solid rgba(99,102,241,.15);
    border-radius: 4px;
    padding: 1px 7px;
    font-family: var(--font-mono);
    font-size: .84em;
}

/* Tables */
.chapter-content table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
    font-size: .86rem;
    border-radius: 8px;
    overflow: hidden;
    border: 1px solid var(--border);
}
.chapter-content th {
    background: var(--bg3);
    padding: 11px 16px;
    text-align: left;
    color: var(--accent);
    font-weight: 700;
    font-size: .78rem;
    text-transform: uppercase;
    letter-spacing: .05em;
    border-bottom: 2px solid var(--border);
}
.chapter-content td {
    padding: 10px 16px;
    border-bottom: 1px solid var(--border);
    color: var(--text-muted);
}
.chapter-content tr:last-child td { border-bottom: none; }
.chapter-content tr:hover td { background: var(--bg3); }

/* Blockquote / Tips */
.chapter-content blockquote {
    border-left: 3px solid var(--accent);
    padding: 1rem 1.4rem;
    margin: 1.4rem 0;
    background: rgba(99,102,241,.04);
    border-radius: 0 8px 8px 0;
    color: var(--text-muted);
}
.chapter-content blockquote strong { color: var(--accent2); }
.chapter-content hr { border: none; border-top: 1px solid var(--border); margin: 2.5rem 0; }
.chapter-content ul, .chapter-content ol { padding-left: 1.6rem; margin-bottom: 1.1rem; }
.chapter-content li { margin-bottom: .4rem; }
.chapter-content li::marker { color: var(--accent); }

/* 常見錯誤 section 特殊樣式 */
.chapter-content h2:has(+ *) { }

/* Nav footer */
.chapter-nav-footer {
    display: flex;
    justify-content: space-between;
    align-items: stretch;
    margin-top: 3.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border);
    gap: 1rem;
}
.nav-prev, .nav-next {
    background: var(--bg2);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 14px 20px;
    font-size: .84rem;
    color: var(--text-muted);
    max-width: 48%;
    transition: all .2s;
    display: block;
}
.nav-prev:hover, .nav-next:hover {
    border-color: var(--accent);
    color: var(--accent);
    text-decoration: none;
    background: rgba(99,102,241,.04);
}
.nav-next { margin-left: auto; text-align: right; }

/* ════════════════════════════════════════════════════════════
   QUIZ MODAL
   ════════════════════════════════════════════════════════════ */
.modal {
    position: fixed; inset: 0; z-index: 500;
    display: flex; align-items: center; justify-content: center;
}
.modal.hidden { display: none; }
.modal-overlay {
    position: fixed; inset: 0;
    background: rgba(0,0,0,.75);
    backdrop-filter: blur(4px);
    z-index: 490;
}
.modal-overlay.hidden { display: none; }
.modal-box {
    background: var(--bg2);
    border: 1px solid var(--border2);
    border-radius: 16px;
    width: 92%;
    max-width: 700px;
    max-height: 88vh;
    overflow-y: auto;
    z-index: 500;
    position: relative;
    box-shadow: 0 16px 48px rgba(0,0,0,.4);
}
.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.3rem 1.6rem;
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    background: var(--bg2);
    z-index: 10;
}
.modal-header h2 { font-size: 1.05rem; color: var(--text); }
.modal-close {
    background: var(--bg3);
    border: 1px solid var(--border);
    color: var(--text-muted);
    font-size: 1rem;
    cursor: pointer;
    padding: 5px 10px;
    border-radius: 6px;
    transition: all .2s;
}
.modal-close:hover { color: var(--accent3); border-color: var(--accent3); }

.quiz-loading { padding: 3rem; text-align: center; color: var(--text-muted); }
.quiz-question { padding: 1.6rem; border-bottom: 1px solid var(--border); }
.q-num { font-size: .7rem; color: var(--text-dim); font-weight: 700; text-transform: uppercase; letter-spacing: .1em; margin-bottom: .5rem; }
.q-text { font-size: .95rem; color: var(--text); margin-bottom: 1.2rem; font-weight: 500; line-height: 1.6; }
.q-options { display: flex; flex-direction: column; gap: .6rem; }
.q-option {
    display: flex;
    align-items: center;
    gap: .8rem;
    padding: 11px 16px;
    border: 1px solid var(--border);
    border-radius: 8px;
    cursor: pointer;
    font-size: .87rem;
    color: var(--text-muted);
    transition: all .18s;
    background: var(--bg3);
}
.q-option:hover { border-color: var(--accent); color: var(--text); background: rgba(99,102,241,.06); }
.q-option input { accent-color: var(--accent2); width: 16px; height: 16px; flex-shrink: 0; }
.q-option.correct { border-color: var(--success); background: rgba(34,197,94,.08); color: var(--success); }
.q-option.wrong   { border-color: var(--danger); background: rgba(239,68,68,.08); color: var(--danger); }

.quiz-actions {
    padding: 1.2rem 1.6rem;
    border-top: 1px solid var(--border);
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
    position: sticky;
    bottom: 0;
    background: var(--bg2);
}
.btn-submit {
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: 8px;
    padding: 11px 28px;
    font-size: .9rem;
    cursor: pointer;
    font-weight: 700;
    font-family: var(--font-sans);
    transition: background .2s, transform .2s;
}
.btn-submit:hover { background: var(--accent3); transform: translateY(-1px); }
.btn-retry {
    background: var(--bg3);
    color: var(--text-muted);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 11px 22px;
    font-size: .9rem;
    cursor: pointer;
    font-family: var(--font-sans);
    transition: all .2s;
}
.btn-retry:hover { border-color: var(--border2); color: var(--text); }

/* Score display */
.quiz-score {
    padding: 2.5rem 2rem;
    text-align: center;
    border-bottom: 1px solid var(--border);
    background: var(--bg2);
}
.score-circle {
    width: 110px; height: 110px;
    border-radius: 50%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.2rem;
    background: var(--bg3);
    border: 4px solid var(--accent);
}
.score-circle.bad  { border-color: var(--danger); }
.score-circle.ok   { border-color: var(--yellow); }
.score-num { font-size: 2rem; font-weight: 800; color: var(--accent); line-height: 1; }
.score-circle.bad .score-num  { color: var(--accent3); }
.score-circle.ok  .score-num  { color: var(--yellow); }
.score-label { font-size: .68rem; color: var(--text-dim); margin-top: 2px; }
.score-msg { font-size: 1.1rem; font-weight: 600; margin-bottom: .3rem; }
.score-sub { color: var(--text-muted); font-size: .85rem; }

.q-result { padding: 1rem 1.6rem; border-bottom: 1px solid var(--border); }
.q-result .q-text { font-size: .87rem; margin-bottom: .5rem; color: var(--text); }
.explanation {
    font-size: .8rem;
    color: var(--text-muted);
    background: rgba(99,102,241,.06);
    border: 1px solid rgba(99,102,241,.12);
    padding: 9px 13px;
    border-radius: 7px;
    margin-top: .6rem;
    line-height: 1.6;
}
.correct-tag { color: var(--accent);  font-weight: 700; }
.wrong-tag   { color: var(--accent3); font-weight: 700; }

/* ════════════════════════════════════════════════════════════
   SCORES PAGE
   ════════════════════════════════════════════════════════════ */
.scores-page { min-height: 100vh; }
.scores-hero {
    background: var(--bg2);
    padding: 3rem 2.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 1rem;
    border-bottom: 1px solid var(--border);
}
.scores-hero h1 { font-size: 2rem; margin-bottom: .3rem; }
.scores-hero p { color: var(--text-muted); }
.btn-excel {
    background: #27AE60;
    color: #fff;
    border: none;
    border-radius: 9px;
    padding: 12px 24px;
    font-size: .88rem;
    font-weight: 700;
    cursor: pointer;
    text-decoration: none;
    white-space: nowrap;
    transition: opacity .2s, transform .2s;
    display: inline-flex;
    align-items: center;
    gap: .4rem;
}
.btn-excel:hover { opacity: .9; transform: translateY(-2px); text-decoration: none; color: #fff; }

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    padding: 2rem;
    max-width: 900px;
    margin: 0 auto;
}
.stat-card {
    background: var(--bg2);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 1.8rem;
    text-align: center;
    transition: transform .25s, box-shadow .25s;
}
.stat-card:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.stat-icon { font-size: 2.2rem; margin-bottom: .8rem; }
.stat-val { font-size: 2.5rem; font-weight: 800; color: var(--accent); }
.stat-sub { font-size: 1.1rem; color: var(--text-muted); font-weight: 400; }
.stat-label { color: var(--text-muted); font-size: .82rem; margin-top: .3rem; }
.stat-bar { height: 5px; background: var(--bg3); border-radius: 3px; margin-top: 1rem; overflow: hidden; }
.stat-bar-fill { height: 100%; background: linear-gradient(90deg, var(--accent), var(--accent2)); border-radius: 3px; }

.scores-section { max-width: 1000px; margin: 0 auto; padding: 0 2rem 3rem; }
.scores-section h2 { font-size: 1.15rem; margin-bottom: 1.2rem; padding-bottom: .6rem; border-bottom: 1px solid var(--border); color: var(--text); }
.empty-state { text-align: center; padding: 4rem 2rem; color: var(--text-muted); }
.empty-icon { font-size: 3.5rem; margin-bottom: 1rem; }
.btn-primary {
    display: inline-block;
    margin-top: 1rem;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: 8px;
    padding: 10px 20px;
    font-weight: 600;
    text-decoration: none;
    transition: background 0.2s, transform 0.1s;
}
.btn-primary:hover { background: var(--accent3); transform: translateY(-1px); text-decoration: none; color: #fff; }

.attempts-table-wrap { overflow-x: auto; }
.attempts-table { width: 100%; border-collapse: collapse; font-size: .87rem; }
.attempts-table th {
    background: var(--bg3);
    padding: 12px 16px;
    text-align: left;
    color: var(--text-muted);
    font-weight: 700;
    font-size: .74rem;
    text-transform: uppercase;
    letter-spacing: .06em;
    border-bottom: 2px solid var(--border);
}
.attempts-table td { padding: 13px 16px; border-bottom: 1px solid var(--border); }
.attempts-table tr:hover td { background: var(--bg3); }
.row-num { color: var(--text-dim); font-size: .8rem; }
.chapter-name { font-weight: 500; color: var(--text); }
.score-pill { display: inline-block; padding: 4px 13px; border-radius: 20px; font-weight: 800; font-size: .84rem; }
.score-pass { background: rgba(34,197,94,.1); color: var(--success); border: 1px solid rgba(34,197,94,.2); }
.score-ok   { background: rgba(245,158,11,.1); color: var(--yellow); border: 1px solid rgba(245,158,11,.2); }
.score-fail { background: rgba(239,68,68,.1); color: var(--danger); border: 1px solid rgba(239,68,68,.2); }
.score-frac { color: var(--text-muted); font-size: .82rem; }
.time-col   { color: var(--text-dim); font-size: .8rem; }
.btn-sm {
    background: var(--bg3);
    border: 1px solid var(--border);
    color: var(--accent2);
    border-radius: 6px;
    padding: 4px 12px;
    font-size: .76rem;
    text-decoration: none;
    transition: all .2s;
    display: inline-block;
}
.btn-sm:hover { background: rgba(99,102,241,.08); border-color: var(--accent2); text-decoration: none; }

/* ════════════════════════════════════════════════════════════
   NOTE CONTROLLER page (category download)
   ════════════════════════════════════════════════════════════ */
/* reuse existing btn-tool */

/* ════════════════════════════════════════════════════════════
   IDEAS — 想法分享
   ════════════════════════════════════════════════════════════ */
.ideas-section {
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border);
}
.ideas-title {
    font-size: 1.1rem;
    margin-bottom: 1.2rem;
    color: var(--text);
}
.idea-list, .idea-wall-grid {
    display: flex;
    flex-direction: column;
    gap: .8rem;
}
.idea-wall-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1rem;
}
.idea-wall-actions {
    text-align: center;
    margin-bottom: 2rem;
}
.idea-card, .idea-wall-card {
    background: var(--bg2);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 1rem;
    transition: all var(--transition);
    box-shadow: 0 2px 8px rgba(0,0,0,.3);
}
.idea-card:hover, .idea-wall-card:hover {
    border-color: var(--accent);
    transform: translateY(-1px);
}
.idea-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: .5rem;
}
.idea-author {
    font-size: .82rem;
    font-weight: 600;
    color: var(--accent);
}
.idea-time {
    font-size: .72rem;
    color: var(--text-dim);
}
.idea-chapter {
    font-size: .72rem;
    color: var(--text-muted);
    background: var(--bg4);
    display: inline-block;
    padding: 2px 8px;
    border-radius: 4px;
    margin-bottom: .5rem;
}
.idea-body {
    font-size: .88rem;
    color: var(--text);
    line-height: 1.6;
    margin-bottom: .6rem;
    word-break: break-word;
}
.idea-like {
    background: none;
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 3px 10px;
    font-size: .75rem;
    color: var(--text-muted);
    cursor: pointer;
    transition: all .15s;
    font-family: var(--font-sans);
}
.idea-like:hover {
    border-color: var(--accent3);
    color: var(--accent3);
    background: rgba(229,57,53,.08);
}
.idea-empty, .idea-loading {
    text-align: center;
    color: var(--text-dim);
    padding: 2rem;
    font-size: .88rem;
}
.idea-actions {
    display: flex;
    gap: .5rem;
    align-items: center;
}
.idea-reply-btn {
    background: none;
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 3px 10px;
    font-size: .75rem;
    color: var(--text-muted);
    cursor: pointer;
    transition: all .15s;
    font-family: var(--font-sans);
}
.idea-reply-btn:hover {
    border-color: var(--accent);
    color: var(--accent);
    background: rgba(99,102,241,.06);
}

/* ── Idea Reply Count Badge & Inline Replies ── */
.idea-reply-count-badge {
    background: rgba(99,102,241,.1);
    color: var(--accent);
    border: 1px solid rgba(99,102,241,.2);
    border-radius: 10px;
    padding: 1px 8px;
    font-size: .7rem;
    font-weight: 600;
    white-space: nowrap;
}
.idea-view-replies-btn {
    border-color: rgba(99,102,241,.25) !important;
    color: var(--accent) !important;
}
.idea-inline-replies {
    margin-top: .6rem;
    padding-top: .6rem;
    border-top: 1px solid var(--border);
}
.inline-reply-item {
    padding: 6px 10px;
    margin-bottom: 4px;
    background: var(--bg3);
    border-radius: 8px;
    font-size: .8rem;
}
.inline-reply-item .reply-author {
    font-weight: 600;
    color: var(--accent);
    margin-right: 6px;
    font-size: .75rem;
}
.inline-reply-item .reply-time {
    font-size: .65rem;
    color: var(--text-dim);
}
.inline-reply-item .reply-body {
    margin-top: 2px;
    color: var(--text-muted);
    line-height: 1.5;
}

/* ── Idea Modal ── */
.idea-modal {
    position: fixed; inset: 0; z-index: 999;
    background: rgba(0,0,0,.6);
    backdrop-filter: blur(6px);
    display: flex; align-items: center; justify-content: center;
    padding: 1rem;
}
.idea-modal-inner {
    background: var(--bg2);
    border: 1px solid var(--border);
    border-radius: 14px;
    max-width: 520px;
    width: 100%;
    max-height: 85vh;
    overflow-y: auto;
    box-shadow: 0 8px 40px rgba(0,0,0,.4);
}
.idea-modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.2rem 1.5rem;
    border-bottom: 1px solid var(--border);
}
.idea-modal-header h3 {
    font-size: 1rem;
    color: var(--text);
}
.idea-modal-close {
    background: none; border: none;
    color: var(--text-muted); font-size: 1.2rem;
    cursor: pointer;
}
.idea-modal-close:hover { color: var(--accent3); }
.idea-modal-body {
    padding: 1.5rem;
}
.idea-form-group {
    margin-bottom: 1rem;
}
.idea-form-group label {
    display: block;
    font-size: .8rem;
    font-weight: 600;
    color: var(--text-muted);
    margin-bottom: .4rem;
}
.idea-form-group input,
.idea-form-group textarea {
    width: 100%;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 10px 12px;
    color: var(--text);
    font-family: var(--font-sans);
    font-size: .88rem;
    transition: border-color .2s;
}
.idea-form-group input:focus,
.idea-form-group textarea:focus {
    outline: none;
    border-color: var(--accent);
}
.idea-form-group textarea { resize: vertical; line-height: 1.6; }
.idea-char-count {
    text-align: right;
    font-size: .7rem;
    color: var(--text-dim);
    margin-top: .3rem;
}
.idea-submit-btn {
    width: 100%;
    padding: 11px;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: 8px;
    font-size: .9rem;
    font-weight: 700;
    cursor: pointer;
    font-family: var(--font-sans);
    transition: all .2s;
}
.idea-submit-btn:hover { background: var(--accent2); }
.idea-submit-btn:disabled { opacity: .5; cursor: not-allowed; }

/* ── Reply ── */
.reply-original {
    background: var(--bg);
    border-left: 3px solid var(--accent);
    border-radius: 6px;
    padding: .8rem 1rem;
    margin-bottom: 1rem;
}
.reply-orig-author { font-size: .8rem; font-weight: 600; color: var(--accent); margin-bottom: .3rem; }
.reply-orig-content { font-size: .85rem; color: var(--text-muted); line-height: 1.5; }
.reply-list {
    max-height: 300px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: .5rem;
}
.reply-item {
    background: var(--bg3);
    border-radius: 8px;
    padding: .7rem .9rem;
}
.reply-author { font-size: .78rem; font-weight: 600; color: var(--accent); margin-right: .5rem; }
.reply-time { font-size: .68rem; color: var(--text-dim); }
.reply-body { font-size: .84rem; color: var(--text); margin-top: .3rem; line-height: 1.5; }

/* ════════════════════════════════════════════════════════════
   Footer
   ════════════════════════════════════════════════════════════ */
.px-footer {
    background: var(--bg2);
    border-top: 1px solid var(--border);
    padding: 2.5rem 2rem 1.5rem;
}
.px-footer-inner {
    max-width: 1200px;
    margin: 0 auto;
}
.px-footer-brand {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1.5rem;
}
.px-footer-title {
    font-size: 1rem;
    font-weight: 700;
    color: var(--text);
}
.px-footer-sub {
    font-size: .78rem;
    color: var(--text-dim);
}
.px-footer-links {
    display: flex;
    gap: 1.5rem;
    margin-bottom: 1.5rem;
}
.px-footer-links a {
    color: var(--text-muted);
    font-size: .85rem;
    transition: color .2s;
}
.px-footer-links a:hover { color: var(--accent); }
.px-footer-copy {
    font-size: .72rem;
    color: var(--text-dim);
}

/* ════════════════════════════════════════════════════════════
   RESPONSIVE
   ════════════════════════════════════════════════════════════ */
/* ════════════════════════════════════════════════════════════
   RESPONSIVE — Hamburger (hidden on desktop)
   ════════════════════════════════════════════════════════════ */
/* Sidebar Toggle (mobile) */
.sidebar-toggle {
    display: none;
    position: fixed; bottom: 16px; left: 16px; z-index: 98;
    background: var(--accent); color: #fff;
    border: none; border-radius: 8px;
    padding: 8px 16px; font-size: .82rem; font-weight: 700;
    font-family: var(--font-sans);
    box-shadow: var(--shadow); cursor: pointer;
}
.sidebar-overlay {
    display: none;
    position: fixed; inset: 0; background: rgba(0,0,0,.5); z-index: 99;
}
.sidebar-overlay.open { display: block; }

.hamburger {
    display: none;
    background: none; border: none; cursor: pointer;
    flex-direction: column; gap: 4px; padding: 6px;
}
.hamburger span {
    display: block; width: 20px; height: 2px;
    background: var(--text); border-radius: 1px;
    transition: all .2s;
}

/* ════════════════════════════════════════════════════════════
   RESPONSIVE — Tablet (≤1024px)
   ════════════════════════════════════════════════════════════ */
@media (max-width: 1024px) {
    .learning-path { gap: .3rem; }
    .path-node { width: 200px; padding: 1.2rem 1rem; }
    .path-node h3 { font-size: .85rem; }
    .path-desc { font-size: .72rem; }
    .courses-container { grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); }
    .core-cards { grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); }
    .chapter-main { padding: 1.5rem; max-width: 100%; }
}

/* ════════════════════════════════════════════════════════════
   RESPONSIVE — Mobile (≤768px)
   ════════════════════════════════════════════════════════════ */
@media (max-width: 768px) {
    :root { --sidebar-w: 0px; --topnav-h: 50px; }

    /* ── Navbar ── */
    .hamburger { display: flex; }
    .topnav { padding: 0 .8rem; gap: .6rem; }
    .nav-search { max-width: none; flex: 1; }
    .nav-search input { font-size: .8rem; padding: 6px 10px 6px 30px; }
    .nav-right {
        display: none;
        position: fixed; top: calc(var(--topnav-h) + var(--marquee-h)); left: 0; right: 0;
        background: var(--bg2); border-bottom: 1px solid var(--border);
        padding: .8rem 1rem;
        flex-direction: column; gap: .5rem; z-index: 199;
    }
    .nav-right.open { display: flex; }
    .nav-scores-link { text-align: center; padding: 8px; }
    .progress-badge { text-align: center; }
    .logo { font-size: .9rem; }

    /* ── Hero ── */
    .hero { min-height: 320px; padding: 2.5rem 1.2rem; }
    .hero h1 { font-size: 1.6rem; }
    .hero p, .hero-desc { font-size: .88rem; }
    .hero-cta { flex-direction: column; align-items: center; gap: .6rem; }
    .btn-cta-primary, .btn-cta-secondary, .btn-cta-ghost {
        width: 100%; max-width: 280px; text-align: center;
        padding: 11px 20px; font-size: .88rem;
    }
    .hero-stats { gap: 1.5rem; }
    .stat-num { font-size: 1.8rem; }

    /* ── Learning Path ── */
    .learning-path { flex-direction: column; gap: 0; }
    .path-node { width: 100%; max-width: 320px; }
    .path-arrow { transform: rotate(90deg); margin: -.5rem 0; }
    .path-arrow svg { width: 24px; height: 40px; }

    /* ── Section ── */
    .section-block { padding: 2rem 1rem .5rem; }
    .section-title { font-size: 1.2rem; }

    /* ── Cards ── */
    .courses-container, .core-cards { grid-template-columns: 1fr; gap: 1rem; padding: 0; }
    .category-header { padding: 1rem; }
    .category-header h2 { font-size: .88rem; }
    .chapter-link { padding: 9px 1rem; font-size: .82rem; }

    /* ── Challenge ── */
    .challenge-options { flex-direction: column; align-items: center; }
    .challenge-btn { width: 100%; max-width: 280px; justify-content: center; }

    /* ── Sidebar (drawer) ── */
    .sidebar-toggle { display: block; }
    .sidebar {
        transform: translateX(-100%);
        width: 280px;
        transition: transform .3s var(--ease-out);
        z-index: 100;
    }
    .sidebar.open { transform: translateX(0); }

    /* ── Chapter Main ── */
    .chapter-main { margin-left: 0; padding: 1rem; }
    .chapter-toolbar { flex-direction: column; align-items: flex-start; gap: .6rem; }
    .toolbar-actions { display: flex; flex-wrap: wrap; gap: .4rem; }
    .btn-tool { font-size: .75rem; padding: 5px 10px; }
    .chapter-nav-footer { flex-direction: column; gap: .5rem; }
    .nav-prev, .nav-next { font-size: .82rem; }

    /* ── Chapter Content ── */
    .chapter-content pre { overflow-x: auto; font-size: .75rem; }
    .chapter-content pre code { white-space: pre; }
    .chapter-content h1 { font-size: 1.4rem; }
    .chapter-content h2 { font-size: 1.15rem; }
    .chapter-content h3 { font-size: 1rem; }
    .chapter-content table { display: block; overflow-x: auto; }

    /* ── Quiz Modal ── */
    .modal-box { width: 95vw; max-height: 90vh; padding: 1rem; border-radius: 12px; }
    .quiz-modal-inner { max-width: 95vw; padding: 1rem; }
    .quiz-q { padding: .8rem; }
    .quiz-option { padding: 6px 8px; font-size: .8rem; }

    /* ── Practice Modal ── */
    #practiceContent > div:first-of-type { flex-direction: column !important; }
    #practiceRef, #practiceInput { min-height: 200px !important; }
}

/* ════════════════════════════════════════════════════════════
   RESPONSIVE — Small phone (≤480px)
   ════════════════════════════════════════════════════════════ */
@media (max-width: 480px) {
    .hero h1 { font-size: 1.3rem; }
    .hero-badge { font-size: .65rem; padding: 4px 10px; }
    .hero-stats { gap: 1rem; }
    .stat-num { font-size: 1.5rem; }
    .stat small { font-size: .68rem; }
    .path-node { padding: 1rem .8rem; }
    .path-icon { font-size: 1.6rem; }
    .chapter-content { font-size: .88rem; }
    .chapter-content pre { font-size: .7rem; padding: .6rem; }
    .cb-num { font-size: 1.5rem; }
}

/* ════════════════════════════════════════════════════════════
   CHAPTER PAGE — Keep Dark Theme
   ════════════════════════════════════════════════════════════ */
.chapter-layout {
    --bg: #0d1117;
    --bg2: #161b22;
    --bg3: #21262d;
    --bg4: #30363d;
    --border: #30363d;
    --border2: #484f58;
    --text: #e6edf3;
    --text-muted: #8b949e;
    --text-dim: #6e7681;
    --accent: #58a6ff;
    --accent2: #79c0ff;
    --accent3: #388bfd;
    --card-bg: rgba(22, 27, 35, 0.8);
    --card-border: rgba(88, 166, 255, 0.1);
    background: #0d1117;
    color: #e6edf3;
}
.chapter-layout .sidebar {
    background: #161b22;
}
.chapter-layout .sidebar-header {
    background: #161b22;
}
.chapter-layout .topnav {
    background: rgba(13,17,23,.95);
    border-bottom-color: #30363d;
}
.chapter-layout .topnav .logo span { color: #fff !important; }

/* Page-light utility class */
.page-light { background: var(--bg2); color: var(--text); }