/* ============================================================
   SimpleFold → Low-Poly Mesh · 站点设计系统
   ============================================================ */

:root {
  --bg: #0b0d12;
  --bg-soft: #12151d;
  --bg-card: #161a24;
  --bg-card-hover: #1c2130;
  --border: #262c3b;
  --border-soft: #1c212e;
  --text: #e8eaf0;
  --text-dim: #9aa3b8;
  --text-faint: #626b82;
  --accent: #7c9eff;
  --accent-soft: #7c9eff22;
  --accent-strong: #a9c1ff;
  --accent2: #ff9d7c;
  --accent2-soft: #ff9d7c22;
  --good: #6fd6a8;
  --good-soft: #6fd6a822;
  --warn: #f2c14e;
  --warn-soft: #f2c14e22;
  --bad: #ef7676;
  --bad-soft: #ef767622;
  --radius: 14px;
  --radius-sm: 8px;
  --shadow: 0 10px 40px -12px rgba(0,0,0,0.6);
  --serif: "Noto Serif SC", "Songti SC", "STSong", Georgia, "Times New Roman", serif;
  --sans: "Inter", "PingFang SC", "Microsoft YaHei", -apple-system, BlinkMacSystemFont, sans-serif;
  --mono: "SF Mono", "JetBrains Mono", Consolas, monospace;
  --max-w: 920px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background:
    radial-gradient(1200px 600px at 15% -10%, #1a2036 0%, transparent 60%),
    radial-gradient(900px 500px at 100% 0%, #2a1f30 0%, transparent 55%),
    var(--bg);
  color: var(--text);
  font-family: var(--sans);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

::selection { background: var(--accent-soft); color: var(--accent-strong); }

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }

.wrap {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- Top nav ---------- */
.topnav {
  position: sticky; top: 0; z-index: 40;
  backdrop-filter: blur(14px) saturate(140%);
  background: rgba(11,13,18,0.72);
  border-bottom: 1px solid var(--border-soft);
}
.topnav .wrap { display: flex; align-items: center; justify-content: space-between; padding: 14px 24px; max-width: 1080px; }
.brand { display: flex; align-items: center; gap: 10px; font-family: var(--serif); font-weight: 700; font-size: 16px; letter-spacing: 0.02em; color: var(--text); }
.brand .dot { width: 9px; height: 9px; border-radius: 50%; background: linear-gradient(135deg, var(--accent), var(--accent2)); box-shadow: 0 0 14px var(--accent-soft); }
.navlinks { display: flex; gap: 22px; font-size: 14px; }
.navlinks a { color: var(--text-dim); }
.navlinks a:hover { color: var(--accent-strong); }
.navlinks a.active { color: var(--text); }

/* ---------- Hero ---------- */
.hero { padding: 84px 0 56px; max-width: 1080px; margin: 0 auto; padding-left: 24px; padding-right: 24px; }
.kicker {
  display: inline-flex; align-items: center; gap: 8px;
  font-size: 12.5px; letter-spacing: 0.08em; text-transform: uppercase;
  color: var(--accent-strong); background: var(--accent-soft);
  border: 1px solid #7c9eff33; padding: 5px 12px; border-radius: 999px;
  margin-bottom: 22px;
}
h1.title {
  font-family: var(--serif); font-weight: 700;
  font-size: clamp(32px, 5vw, 50px); line-height: 1.28; margin: 0 0 18px;
  letter-spacing: 0.01em;
}
h1.title .accent { color: var(--accent); font-style: italic; }
.lede { font-size: 17.5px; color: var(--text-dim); max-width: 680px; margin: 0 0 8px; }
.meta-row { display: flex; gap: 18px; flex-wrap: wrap; margin-top: 26px; font-size: 13px; color: var(--text-faint); }
.meta-row span { display: inline-flex; align-items: center; gap: 6px; }

/* ---------- Cards / nav grid ---------- */
.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 18px; margin: 36px 0; }
.card {
  background: linear-gradient(180deg, var(--bg-card), var(--bg-soft));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  position: relative;
  transition: transform .22s ease, border-color .22s ease, box-shadow .22s ease;
}
.card:hover { transform: translateY(-3px); border-color: #3a4258; box-shadow: var(--shadow); }
.card .card-icon { font-size: 22px; margin-bottom: 14px; display: inline-block; }
.card h3 { font-family: var(--serif); margin: 0 0 8px; font-size: 19px; }
.card p { margin: 0; color: var(--text-dim); font-size: 14.5px; }
.card .lock-badge {
  position: absolute; top: 18px; right: 18px;
  font-size: 11px; color: var(--warn); background: var(--warn-soft);
  border: 1px solid #f2c14e33; padding: 3px 9px; border-radius: 999px;
  letter-spacing: 0.03em;
}
.card .go { display: inline-block; margin-top: 16px; font-size: 13.5px; color: var(--accent-strong); }

/* ---------- Section ---------- */
section.block { padding: 40px 0; }
.section-label { font-size: 12.5px; letter-spacing: .1em; text-transform: uppercase; color: var(--text-faint); margin-bottom: 10px; }
h2 { font-family: var(--serif); font-size: 28px; margin: 48px 0 18px; letter-spacing: 0.01em; border-left: 3px solid var(--accent); padding-left: 14px; }
h3 { font-family: var(--serif); font-size: 20px; margin: 30px 0 12px; color: var(--accent-strong); }
p { color: #d3d7e2; font-size: 15.5px; }
.prose p, .prose li { color: #d3d7e2; font-size: 15.8px; }
.prose { max-width: 760px; }
.prose blockquote {
  margin: 20px 0; padding: 12px 18px; border-left: 3px solid var(--accent2);
  background: var(--accent2-soft); color: var(--text-dim); border-radius: 0 8px 8px 0; font-size: 14.5px;
}
.prose table { width: 100%; border-collapse: collapse; margin: 22px 0; font-size: 14px; }
.prose th, .prose td { border: 1px solid var(--border); padding: 10px 12px; text-align: left; vertical-align: top; }
.prose th { background: var(--bg-card); color: var(--accent-strong); font-weight: 600; }
.prose tr:nth-child(even) td { background: #ffffff05; }
.prose code { font-family: var(--mono); background: #ffffff0d; padding: 2px 6px; border-radius: 4px; font-size: 0.88em; color: var(--accent-strong); }
.prose hr { border: none; border-top: 1px solid var(--border); margin: 40px 0; }

.formula {
  font-family: var(--mono); background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius-sm); padding: 18px 22px; margin: 18px 0; font-size: 16px;
  color: var(--accent-strong); overflow-x: auto; text-align: center;
}
.formula .fname { display: block; font-family: var(--sans); font-size: 12px; color: var(--text-faint); margin-bottom: 8px; text-transform: uppercase; letter-spacing: .06em; }

.badge { display: inline-block; font-size: 11px; padding: 2px 9px; border-radius: 999px; font-weight: 600; letter-spacing: .02em; }
.badge.high { color: var(--good); background: var(--good-soft); border: 1px solid #6fd6a833; }
.badge.mid { color: var(--warn); background: var(--warn-soft); border: 1px solid #f2c14e33; }
.badge.low { color: var(--bad); background: var(--bad-soft); border: 1px solid #ef767633; }
.badge.verified { color: var(--accent-strong); background: var(--accent-soft); border: 1px solid #7c9eff33; }

/* ---------- Paper cards ---------- */
.paper {
  background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 26px 28px; margin: 22px 0;
}
.paper-head { display: flex; justify-content: space-between; align-items: flex-start; gap: 14px; flex-wrap: wrap; }
.paper-head h3 { margin: 0; }
.paper-meta { font-size: 13px; color: var(--text-faint); margin: 4px 0 14px; font-family: var(--mono); }
.paper dl { display: grid; grid-template-columns: 110px 1fr; gap: 8px 16px; margin: 14px 0 0; font-size: 14.5px; }
.paper dt { color: var(--text-faint); font-weight: 600; }
.paper dd { margin: 0; color: #d3d7e2; }

/* ---------- Gate ---------- */
.gate-wrap { min-height: 60vh; display: flex; align-items: center; justify-content: center; padding: 60px 20px; }
.gate-box {
  width: 100%; max-width: 420px; background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 36px 32px; text-align: center; box-shadow: var(--shadow);
}
.gate-box .icon { font-size: 30px; margin-bottom: 6px; }
.gate-box h2 { border: none; padding: 0; margin: 6px 0 6px; font-size: 21px; }
.gate-box p.hint { color: var(--text-faint); font-size: 13.5px; margin: 0 0 22px; }
.gate-box input {
  width: 100%; background: var(--bg); border: 1px solid var(--border); color: var(--text);
  padding: 12px 14px; border-radius: var(--radius-sm); font-size: 15px; font-family: var(--mono);
  outline: none; transition: border-color .2s;
}
.gate-box input:focus { border-color: var(--accent); }
.gate-box button {
  width: 100%; margin-top: 14px; padding: 12px 14px; border-radius: var(--radius-sm);
  border: none; background: linear-gradient(135deg, var(--accent), #5a7de0); color: #0b0d12;
  font-weight: 700; font-size: 14.5px; cursor: pointer; transition: filter .2s, transform .1s;
}
.gate-box button:hover { filter: brightness(1.08); }
.gate-box button:active { transform: scale(0.98); }
.gate-err { color: var(--bad); font-size: 13px; margin-top: 12px; min-height: 18px; }
.gate-box .back { display: inline-block; margin-top: 18px; font-size: 13px; color: var(--text-faint); }

/* ---------- Demo page ---------- */
.demo-stage {
  background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius);
  overflow: hidden; margin: 24px 0;
}
#three-canvas { width: 100%; height: 440px; display: block; touch-action: none; }
.controls { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px,1fr)); gap: 20px; padding: 22px 24px; border-top: 1px solid var(--border-soft); background: var(--bg-soft); }
.ctrl label { display: block; font-size: 12.5px; color: var(--text-faint); margin-bottom: 8px; letter-spacing: .03em; text-transform: uppercase; }
.ctrl input[type=range] { width: 100%; accent-color: var(--accent); }
.ctrl .val { font-family: var(--mono); color: var(--accent-strong); font-size: 13px; }
.demo-fallback { padding: 40px; text-align: center; color: var(--text-faint); font-size: 14px; display: none; }

.flow-diagram { display: flex; align-items: center; justify-content: space-between; gap: 8px; margin: 30px 0; flex-wrap: wrap; }
.flow-node {
  flex: 1; min-width: 120px; text-align: center; background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius-sm); padding: 18px 10px; font-size: 13.5px; position: relative;
}
.flow-node .n-icon { font-size: 22px; display: block; margin-bottom: 8px; }
.flow-arrow { color: var(--accent); font-size: 20px; opacity: .7; }
.flow-node.pulse { animation: pulseGlow 2.4s ease-in-out infinite; }
@keyframes pulseGlow {
  0%, 100% { box-shadow: 0 0 0 0 var(--accent-soft); border-color: var(--border); }
  50% { box-shadow: 0 0 0 6px transparent; border-color: var(--accent); }
}

.noise-strip { display: flex; gap: 6px; padding: 26px 0; align-items: center; justify-content: center; flex-wrap: wrap; }
.noise-frame { width: 74px; height: 74px; border-radius: 10px; background: var(--bg-card); border: 1px solid var(--border); position: relative; overflow: hidden; }
.noise-frame .dot { position: absolute; width: 4px; height: 4px; border-radius: 50%; background: var(--accent2); }
.noise-arrow { color: var(--text-faint); font-size: 16px; }

/* ---------- Compare chart ---------- */
.chart-card { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 24px; margin: 24px 0; }
.chart-card canvas { max-height: 320px; }

/* ---------- Footer ---------- */
footer { border-top: 1px solid var(--border-soft); padding: 40px 0 60px; color: var(--text-faint); font-size: 13px; }
footer .wrap { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 12px; }

/* ---------- Misc ---------- */
.note {
  background: var(--warn-soft); border: 1px solid #f2c14e33; border-radius: var(--radius-sm);
  padding: 14px 16px; font-size: 13.5px; color: #e9d197; margin: 20px 0;
}
.note.info { background: var(--accent-soft); border-color: #7c9eff33; color: #c3d2ff; }
.toc { font-size: 13.5px; color: var(--text-dim); display: flex; flex-wrap: wrap; gap: 6px 18px; margin: 18px 0 0; }
.toc a { color: var(--text-dim); }
.toc a:hover { color: var(--accent-strong); }

.fade-up { animation: fadeUp .7s ease both; }
@keyframes fadeUp { from { opacity: 0; transform: translateY(14px); } to { opacity: 1; transform: translateY(0); } }

.gate-box.shake { animation: shake .32s ease; }
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-8px); }
  75% { transform: translateX(8px); }
}

.noise-frame .dot { animation: dotDrift 3.2s ease-in-out infinite; }
@keyframes dotDrift {
  0%, 100% { transform: translate(0, 0); }
  50% { transform: translate(1.5px, -1.5px); }
}

@media (max-width: 640px) {
  .navlinks { gap: 12px; font-size: 12.5px; flex-wrap: wrap; justify-content: flex-end; }
  .topnav .wrap { flex-wrap: wrap; gap: 8px; }
  .hero { padding: 56px 0 40px; }
  .paper dl { grid-template-columns: 1fr; }
  .paper dt { margin-top: 6px; }
  .flow-diagram { flex-direction: column; }
  .flow-arrow { transform: rotate(90deg); }
}