:root {
    --bg: #0f1419;
    --card: #1a2332;
    --card-hover: #1f2b3d;
    --border: #2d3a4d;
    --text: #e6edf3;
    --text-dim: #8b9bb4;
    --accent: #58a6ff;
    --accent2: #3fb950;
    --accent3: #d29922;
    --accent4: #f85149;
    --accent5: #bc8cff;
    --radius: 12px;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
    background: var(--bg);
    color: var(--text);
    font-family: -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    line-height: 1.7;
    padding: 0 20px 60px;
}
.container { max-width: 1100px; margin: 0 auto; }

/* Header */
header {
    text-align: center;
    padding: 60px 20px 40px;
    border-bottom: 1px solid var(--border);
    margin-bottom: 50px;
}
header h1 {
    font-size: 2.6em;
    font-weight: 800;
    background: linear-gradient(135deg, var(--accent), var(--accent5));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 16px;
}
header p {
    color: var(--text-dim);
    font-size: 1.15em;
    max-width: 680px;
    margin: 0 auto;
}
.badge-row {
    display: flex;
    gap: 10px;
    justify-content: center;
    margin-top: 20px;
    flex-wrap: wrap;
}
.badge {
    padding: 4px 14px;
    border-radius: 20px;
    font-size: 0.82em;
    font-weight: 600;
    border: 1px solid var(--border);
    color: var(--text-dim);
}
.badge.hot { border-color: var(--accent); color: var(--accent); }
.badge.green { border-color: var(--accent2); color: var(--accent2); }

/* Section */
section { margin-bottom: 56px; }
.section-title {
    font-size: 1.6em;
    font-weight: 700;
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    gap: 10px;
}
.section-title .num {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px; height: 36px;
    border-radius: 10px;
    background: var(--accent);
    color: #000;
    font-size: 0.85em;
    font-weight: 800;
    flex-shrink: 0;
}
.section-desc {
    color: var(--text-dim);
    margin-bottom: 28px;
    font-size: 1.02em;
    padding-left: 46px;
}

/* Analogy box */
.analogy {
    background: linear-gradient(135deg, #1a2a3a, #1a2332);
    border-left: 3px solid var(--accent3);
    padding: 18px 22px;
    border-radius: 0 var(--radius) var(--radius) 0;
    margin-bottom: 28px;
    font-size: 0.95em;
}
.analogy strong { color: var(--accent3); }

/* Card grid */
.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 18px; }
.card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    transition: all 0.25s;
    position: relative;
    overflow: hidden;
}
.card:hover {
    background: var(--card-hover);
    border-color: var(--accent);
    transform: translateY(-3px);
    box-shadow: 0 8px 24px rgba(88,166,255,0.1);
}
.card .icon {
    width: 44px; height: 44px;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.3em;
    margin-bottom: 14px;
}
.card h3 {
    font-size: 1.1em;
    font-weight: 700;
    margin-bottom: 8px;
}
.card p {
    color: var(--text-dim);
    font-size: 0.9em;
}
.card .tag {
    display: inline-block;
    margin-top: 12px;
    padding: 3px 10px;
    border-radius: 6px;
    font-size: 0.78em;
    font-weight: 600;
    background: rgba(88,166,255,0.12);
    color: var(--accent);
}
.card .tag.green { background: rgba(63,185,80,0.12); color: var(--accent2); }
.card .tag.yellow { background: rgba(210,153,34,0.12); color: var(--accent3); }
.card .tag.purple { background: rgba(188,140,255,0.12); color: var(--accent5); }
.card .tag.red { background: rgba(248,81,73,0.12); color: var(--accent4); }

/* Flow diagram */
.flow {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0;
    flex-wrap: wrap;
    padding: 30px 10px;
    background: var(--card);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    margin-bottom: 24px;
    overflow-x: auto;
}
.flow-node {
    padding: 12px 20px;
    border-radius: 10px;
    font-weight: 700;
    font-size: 0.9em;
    text-align: center;
    min-width: 90px;
    border: 2px solid;
    position: relative;
}
.flow-node .sub {
    font-weight: 400;
    font-size: 0.72em;
    opacity: 0.7;
    display: block;
    margin-top: 3px;
}
.flow-node.state { border-color: var(--accent5); color: var(--accent5); background: rgba(188,140,255,0.08); }
.flow-node.node { border-color: var(--accent); color: var(--accent); background: rgba(88,166,255,0.08); }
.flow-node.edge { border-color: var(--accent3); color: var(--accent3); background: rgba(210,153,34,0.08); }
.flow-node.checkpoint { border-color: var(--accent2); color: var(--accent2); background: rgba(63,185,80,0.08); }
.flow-arrow {
    color: var(--text-dim);
    font-size: 1.4em;
    padding: 0 8px;
    flex-shrink: 0;
}

/* Comparison table */
.compare-table {
    width: 100%;
    border-collapse: collapse;
    background: var(--card);
    border-radius: var(--radius);
    overflow: hidden;
    border: 1px solid var(--border);
}
.compare-table th {
    background: rgba(88,166,255,0.1);
    padding: 14px 18px;
    text-align: left;
    font-size: 0.88em;
    font-weight: 700;
    color: var(--accent);
    border-bottom: 1px solid var(--border);
}
.compare-table td {
    padding: 13px 18px;
    font-size: 0.88em;
    border-bottom: 1px solid var(--border);
    color: var(--text-dim);
    vertical-align: top;
}
.compare-table tr:last-child td { border-bottom: none; }
.compare-table td:first-child { color: var(--text); font-weight: 600; }

/* Capability list */
.cap-list { display: flex; flex-direction: column; gap: 14px; }
.cap-item {
    display: flex;
    gap: 16px;
    align-items: flex-start;
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px 22px;
    transition: border-color 0.2s;
}
.cap-item:hover { border-color: var(--accent2); }
.cap-item .cap-icon {
    width: 40px; height: 40px;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.15em;
    flex-shrink: 0;
    background: rgba(63,185,80,0.1);
}
.cap-item h4 { font-size: 1em; font-weight: 700; margin-bottom: 5px; }
.cap-item p { color: var(--text-dim); font-size: 0.88em; }

/* Learning path */
.path { position: relative; padding-left: 36px; }
.path::before {
    content: '';
    position: absolute;
    left: 14px;
    top: 8px;
    bottom: 8px;
    width: 2px;
    background: linear-gradient(to bottom, var(--accent), var(--accent2), var(--accent5));
    opacity: 0.4;
}
.path-item {
    position: relative;
    margin-bottom: 28px;
}
.path-item::before {
    content: '';
    position: absolute;
    left: -30px;
    top: 8px;
    width: 12px; height: 12px;
    border-radius: 50%;
    background: var(--accent);
    border: 2px solid var(--bg);
    box-shadow: 0 0 0 2px var(--accent);
}
.path-item .stage {
    font-size: 0.78em;
    font-weight: 700;
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 4px;
}
.path-item h4 { font-size: 1.02em; font-weight: 700; margin-bottom: 6px; }
.path-item .mods {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    margin-bottom: 6px;
}
.path-item .mods span {
    font-size: 0.75em;
    padding: 3px 9px;
    border-radius: 6px;
    background: rgba(88,166,255,0.1);
    color: var(--accent);
    font-weight: 600;
}
.path-item p { color: var(--text-dim); font-size: 0.88em; }

/* Footer */
footer {
    text-align: center;
    padding-top: 40px;
    border-top: 1px solid var(--border);
    color: var(--text-dim);
    font-size: 0.85em;
}
footer a {
    color: var(--accent);
    text-decoration: none;
}
footer a:hover { text-decoration: underline; }

@media (max-width: 640px) {
    header h1 { font-size: 1.8em; }
    .flow { flex-direction: column; gap: 6px; }
    .flow-arrow { transform: rotate(90deg); padding: 2px 0; }
}

/* Scroll reveal — 由 js/main.js 添加 .reveal-ready，无 JS 时完全不影响展示 */
.reveal-ready .reveal {
    opacity: 0;
    transform: translateY(16px);
    transition: opacity 0.5s ease, transform 0.5s ease;
}
.reveal-ready .reveal.visible {
    opacity: 1;
    transform: none;
}
@media (prefers-reduced-motion: reduce) {
    .reveal-ready .reveal {
        opacity: 1;
        transform: none;
        transition: none;
    }
}