/* ===== RESET & BASE ===== */
:root {
  --bg: #0a0a1a;
  --bg-card: #12122a;
  --bg-card-hover: #1a1a3a;
  --border: #1e1e3a;
  --text: #c8c8d8;
  --text-muted: #6a6a8a;
  --accent: #7aa2f7;
  --accent2: #bb9af7;
  --accent3: #9ece6a;
  --accent4: #e0af68;
  --white: #e8e8f0;
  --yang: #e0af68;
  --yin: #bb9af7;
  --radius: 12px;
  --radius-sm: 8px;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { padding-top: 56px; }
body {
  font-family: -apple-system, "SF Pro Display", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); text-decoration: none; transition: color .2s; }
a:hover { color: var(--accent2); }
.container { max-width: 1000px; margin: 0 auto; padding: 0 24px; }

/* ===== NAV ===== */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  background: #0a0a1a;
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
}
.nav-inner {
  max-width: 1000px; margin: 0 auto;
  display: flex; align-items: center; justify-content: space-between;
  height: 56px;
}
.nav-brand {
  font-size: 18px; font-weight: 700; color: var(--white);
  letter-spacing: 1px; display: flex; align-items: center; gap: 8px;
}
.brand-ai { color: var(--accent); }
.nav-links { display: flex; gap: 4px; }
.nav-links a {
  color: var(--text-muted); font-size: 14px; padding: 6px 14px;
  border-radius: 6px; transition: all .2s;
}
.nav-links a:hover, .nav-links a.active {
  color: var(--white); background: rgba(122, 162, 247, 0.1);
}
.nav-yang:hover, .nav-yang.active { color: var(--yang) !important; background: rgba(224,175,104,0.1) !important; }
.nav-yin:hover, .nav-yin.active { color: var(--yin) !important; background: rgba(187,154,247,0.1) !important; }
.nav-toggle { display: none; background: none; border: none; color: var(--text); font-size: 24px; cursor: pointer; }

/* ===== HERO ===== */
.hero {
  text-align: center;
  padding: 100px 24px 60px;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute; top: 0; left: 0; right: 0; bottom: 0;
  background: radial-gradient(ellipse at 50% 0%, rgba(122,162,247,0.08) 0%, transparent 70%);
  pointer-events: none;
}
.hero h1 {
  font-size: 42px; color: var(--white); font-weight: 800;
  letter-spacing: 2px; margin-bottom: 12px;
  background: linear-gradient(135deg, var(--accent), var(--accent2));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero p {
  font-size: 16px; color: var(--text-muted); max-width: 560px; margin: 0 auto 40px;
}

/* ===== DUAL ENTRANCE ===== */
.dual-entrance {
  display: grid; grid-template-columns: 1fr 1fr; gap: 24px;
  max-width: 700px; margin: 0 auto;
}
.entrance {
  display: flex; flex-direction: column; align-items: center;
  padding: 36px 24px; border-radius: var(--radius);
  border: 1px solid var(--border); transition: all .3s;
  text-decoration: none;
}
.entrance-yang { background: linear-gradient(180deg, rgba(224,175,104,0.06) 0%, var(--bg-card) 100%); }
.entrance-yang:hover { border-color: var(--yang); transform: translateY(-4px); box-shadow: 0 12px 32px rgba(224,175,104,0.15); }
.entrance-yin { background: linear-gradient(180deg, rgba(187,154,247,0.06) 0%, var(--bg-card) 100%); }
.entrance-yin:hover { border-color: var(--yin); transform: translateY(-4px); box-shadow: 0 12px 32px rgba(187,154,247,0.15); }
.entrance-icon { font-size: 40px; margin-bottom: 12px; }
.entrance-label { font-size: 22px; font-weight: 800; color: var(--white); margin-bottom: 4px; }
.entrance-sub { font-size: 13px; color: var(--text-muted); margin-bottom: 8px; }
.entrance-desc { font-size: 12px; color: var(--text-muted); }
.entrance-yang .entrance-label { color: var(--yang); }
.entrance-yin .entrance-label { color: var(--yin); }

/* ===== SECTION ===== */
.section { padding: 60px 0; }
.section-title {
  font-size: 20px; font-weight: 700; color: var(--white);
  margin-bottom: 8px; display: flex; align-items: center; gap: 10px;
}
.section-title .icon { font-size: 22px; }
.section-desc { font-size: 13px; color: var(--text-muted); margin-bottom: 28px; }

/* ===== CARD GRID ===== */
.card-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 16px; }
.card {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 24px;
  transition: all .25s; border-left: 3px solid transparent;
}
.card:hover {
  background: var(--bg-card-hover); border-left-color: var(--accent);
  transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,0,0,0.3);
}
.card-yang:hover { border-left-color: var(--yang); }
.card-yin:hover { border-left-color: var(--yin); }
.card h3 { font-size: 16px; color: var(--white); margin-bottom: 6px; }
.card h3 a { color: var(--white); }
.card h3 a:hover { color: var(--accent); }
.card .meta { font-size: 12px; color: var(--text-muted); margin-bottom: 10px; }
.card .desc { font-size: 13.5px; color: var(--text); line-height: 1.7; }
.card-side {
  font-size: 11px; font-weight: 600; margin-bottom: 8px;
  padding: 2px 8px; border-radius: 4px; display: inline-block;
}
.card-yang .card-side { background: rgba(224,175,104,0.1); color: var(--yang); }
.card-yin .card-side { background: rgba(187,154,247,0.1); color: var(--yin); }

.tag {
  display: inline-block; font-size: 11px; padding: 2px 8px;
  border-radius: 4px; margin-right: 4px; margin-bottom: 4px;
  background: rgba(122, 162, 247, 0.1); color: var(--accent);
}
.tag-green { background: rgba(158, 206, 106, 0.1); color: var(--accent3); }
.tag-purple { background: rgba(187, 154, 247, 0.1); color: var(--accent2); }
.tag-orange { background: rgba(224, 175, 104, 0.1); color: var(--accent4); }

/* ===== SIDE HEADER ===== */
.side-header { margin-bottom: 32px; }
.side-header h1 { font-size: 28px; font-weight: 800; margin-bottom: 8px; }
.side-header p { font-size: 14px; color: var(--text-muted); }
.yang-header h1 { color: var(--yang); }
.yin-header h1 { color: var(--yin); }

/* ===== SUB NAV ===== */
.sub-nav { display: flex; gap: 8px; margin-bottom: 28px; flex-wrap: wrap; }
.sub-link {
  font-size: 13px; padding: 6px 16px; border-radius: 6px;
  border: 1px solid var(--border); color: var(--text-muted);
  transition: all .2s;
}
.sub-link:hover { color: var(--white); border-color: var(--accent); background: rgba(122,162,247,0.08); }

/* ===== ARTICLE ===== */
article {
  background: var(--bg-card); border-radius: var(--radius);
  padding: 40px; border: 1px solid var(--border);
}
article h1 { font-size: 26px; color: var(--white); margin-bottom: 12px; line-height: 1.4; }
article .meta {
  font-size: 13px; color: var(--text-muted); margin-bottom: 28px;
  padding-bottom: 20px; border-bottom: 1px solid var(--border);
}
article .content { font-size: 15px; }
article .content p { margin-bottom: 16px; }
article .content h2 { color: var(--white); font-size: 20px; margin: 32px 0 12px; }
article .content h3 { color: var(--accent); font-size: 17px; margin: 24px 0 10px; }
article .content code {
  background: rgba(187, 154, 247, 0.1); padding: 2px 6px;
  border-radius: 4px; font-size: 13px; color: var(--accent2);
}
article .content pre {
  background: #0d0d20; padding: 20px; border-radius: var(--radius-sm);
  overflow-x: auto; margin: 16px 0; border: 1px solid var(--border);
}
article .content pre code { background: none; padding: 0; }
article .content blockquote {
  border-left: 3px solid var(--accent); padding: 12px 20px;
  margin: 16px 0; background: rgba(122, 162, 247, 0.05);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}
article .content ul, article .content ol { margin: 12px 0 12px 20px; }
article .content li { margin-bottom: 6px; }
article .content hr {
  border: none; border-top: 1px solid var(--border); margin: 32px 0;
}
.article-yang { border-left: 3px solid var(--yang); }
.article-yin { border-left: 3px solid var(--yin); }
.article-yin .content h3 { color: var(--yin); }

/* ===== TIMELINE ===== */
.timeline { position: relative; padding-left: 28px; }
.timeline::before {
  content: ''; position: absolute; left: 8px; top: 0; bottom: 0;
  width: 2px; background: var(--border);
}
.timeline-item { position: relative; margin-bottom: 28px; }
.timeline-item::before {
  content: ''; position: absolute; left: -24px; top: 6px;
  width: 10px; height: 10px; border-radius: 50%;
  background: var(--accent); border: 2px solid var(--bg);
}
.timeline-item .date { font-size: 12px; color: var(--accent); font-weight: 600; margin-bottom: 4px; }
.timeline-item .title { font-size: 15px; color: var(--white); font-weight: 600; margin-bottom: 4px; }
.timeline-item .detail { font-size: 13px; color: var(--text-muted); }

/* ===== PROJECT CARDS ===== */
.project-card {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 28px;
  display: flex; flex-direction: column; gap: 12px;
  transition: all .25s;
}
.project-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,0,0,0.3);
}
.project-card .project-icon { font-size: 32px; }
.project-card h3 { font-size: 17px; color: var(--white); }
.project-card .tech { display: flex; flex-wrap: wrap; gap: 4px; }
.project-card .desc { font-size: 13.5px; color: var(--text); }

/* ===== ABOUT BRIEF ===== */
.about-cards { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.about-card-mini {
  border-radius: var(--radius); padding: 24px;
  border: 1px solid var(--border);
}
.yang-bg { background: linear-gradient(135deg, rgba(224,175,104,0.06) 0%, var(--bg-card) 100%); }
.yin-bg { background: linear-gradient(135deg, rgba(187,154,247,0.06) 0%, var(--bg-card) 100%); }
.about-label { font-size: 14px; font-weight: 700; color: var(--white); margin-bottom: 8px; }
.about-text { font-size: 13px; color: var(--text-muted); line-height: 1.7; }

/* ===== ABOUT PAGE ===== */
.about-card {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 40px;
}
.about-card h2 { color: var(--white); font-size: 20px; margin-bottom: 16px; }
.about-card p { margin-bottom: 12px; }
.about-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 24px; }
.about-item {
  background: rgba(122, 162, 247, 0.05); border-radius: var(--radius-sm);
  padding: 16px; border: 1px solid var(--border);
}
.about-item .label { font-size: 12px; color: var(--text-muted); margin-bottom: 4px; }
.about-item .value { font-size: 15px; color: var(--white); font-weight: 600; }

/* ===== FOOTER ===== */
footer {
  text-align: center; padding: 40px 0; margin-top: 40px;
  border-top: 1px solid var(--border); color: var(--text-muted); font-size: 12px;
}
footer a { color: var(--accent); }

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  .hero { padding: 60px 16px 40px; }
  .hero h1 { font-size: 28px; }
  .dual-entrance { grid-template-columns: 1fr; max-width: 400px; }
  .card-grid { grid-template-columns: 1fr; }
  .about-grid { grid-template-columns: 1fr; }
  .about-cards { grid-template-columns: 1fr; }
  article { padding: 24px; }
  .nav-links {
    display: none; position: absolute; top: 56px; left: 0; right: 0;
    background: #0a0a1a;
    flex-direction: column; padding: 12px; border-bottom: 1px solid var(--border);
  }
  .nav-links.open { display: flex; }
  .nav-toggle { display: block; }
  .container { padding: 0 16px; }
  .section { padding: 40px 0; }
}
@media (max-width: 480px) {
  .hero h1 { font-size: 24px; }
  .hero p { font-size: 14px; }
}