/* ============================================================
   3DGS · Antialiasing — visual essay stylesheet
   Warm coral/peach palette: edges meant to be soft
   ============================================================ */

:root {
  --bg:         #0d0a0c;
  --bg-soft:    #161115;
  --bg-card:    #1c1518;
  --bg-deep:    #07060a;
  --line:       #2b1f25;
  --line-soft:  #221820;
  --text:       #f0e6e3;
  --text-dim:   #c0a8a8;
  --text-muted: #80686f;
  --accent:     #ff8a6a;       /* coral */
  --accent-2:   #ffcf66;       /* honey */
  --accent-3:   #ff5c87;       /* pink */
  --accent-4:   #94d4ff;       /* contrast cool */
  --good:       #80d8a4;
  --warn:       #ffcf66;
  --bad:        #ff5c87;

  --ff-display: "Fraunces", Georgia, serif;
  --ff-body:    "Inter", system-ui, sans-serif;
  --ff-mono:    "JetBrains Mono", ui-monospace, Menlo, monospace;

  --measure:    72ch;
  --gutter:     24px;
  --nav-h:      56px;
  --radius:     14px;
}

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

body {
  margin: 0; background: var(--bg); color: var(--text);
  font-family: var(--ff-body); font-size: 17px; line-height: 1.65;
  -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility;
}

::selection { background: var(--accent); color: #1a0d09; }

a { color: var(--accent-2); text-decoration: none;
  border-bottom: 1px solid rgba(255,207,102,0.28); transition: color 0.15s, border-color 0.15s; }
a:hover { color: var(--accent); border-color: var(--accent); }
em { font-style: italic; color: var(--text); }
strong { color: #fff; font-weight: 600; }

code, pre { font-family: var(--ff-mono); font-size: 0.92em; }
code { background: rgba(255,255,255,0.05); padding: 0.1em 0.35em; border-radius: 4px;
  border: 1px solid var(--line-soft); color: #ffd6a8; }
pre { background: var(--bg-deep) !important; border: 1px solid var(--line); border-radius: var(--radius);
  padding: 18px 20px !important; overflow-x: auto; margin: 1.4em 0; font-size: 13.5px; line-height: 1.55; }
pre code { background: none; border: none; padding: 0; color: inherit; }

h1, h2, h3, h4 { font-family: var(--ff-display); font-weight: 600; letter-spacing: -0.01em; color: #fff; line-height: 1.15; }
h1 { font-size: clamp(2.4rem, 5.5vw, 4.6rem); }
h2 { font-size: clamp(1.7rem, 3vw, 2.4rem); margin: 0 0 0.4em; }
h3 { font-size: 1.3rem; margin: 2.5em 0 0.5em; color: var(--accent); }
h4 { font-size: 1.0rem; margin: 1.4em 0 0.4em; color: #fff; }
p { margin: 0 0 1em; }
ul, ol { padding-left: 1.4em; margin: 0 0 1.2em; }
li { margin: 0.4em 0; }

/* ===== NAV ===== */
#topnav { position: sticky; top: 0; z-index: 50;
  background: rgba(13,10,12,0.85); backdrop-filter: blur(12px) saturate(140%);
  border-bottom: 1px solid var(--line); height: var(--nav-h); }
.nav-inner { max-width: 1100px; margin: 0 auto; height: 100%;
  padding: 0 var(--gutter); display: flex; align-items: center; justify-content: space-between; gap: 16px; }
.brand { display: flex; align-items: center; gap: 10px;
  font-family: var(--ff-mono); font-size: 13px; font-weight: 700;
  color: #fff; letter-spacing: 0.04em; border: none; }
.brand:hover { color: var(--accent); }
.logo-dot { display: inline-block; width: 11px; height: 11px; border-radius: 50%;
  background: radial-gradient(circle at 30% 30%, var(--accent) 0%, var(--accent-3) 60%, transparent 100%);
  box-shadow: 0 0 12px var(--accent); }
#navlinks { display: flex; gap: 22px; list-style: none; margin: 0; padding: 0; }
#navlinks a { font-size: 13.5px; color: var(--text-dim); border: none; font-weight: 500; }
#navlinks a:hover { color: var(--accent); }
#navtoggle { display: none; background: none; border: none; color: var(--text); font-size: 22px; cursor: pointer; }
#progress-bar { position: absolute; bottom: -1px; left: 0; height: 2px; width: 0%;
  background: linear-gradient(90deg, var(--accent), var(--accent-3)); }

/* ===== HERO ===== */
.hero { position: relative; min-height: 88vh;
  display: flex; align-items: center; padding: 120px var(--gutter) 80px;
  overflow: hidden; border-bottom: 1px solid var(--line); }
#hero-canvas { position: absolute; inset: 0; width: 100%; height: 100%; z-index: 0; opacity: 0.55; }
.hero-content { position: relative; z-index: 1; max-width: 880px; margin: 0 auto; }
.kicker { font-family: var(--ff-mono); font-size: 12px;
  letter-spacing: 0.16em; text-transform: uppercase; color: var(--accent); margin: 0 0 24px; }
.hero h1 { margin: 0 0 28px; }
.hero h1 em { font-style: italic;
  background: linear-gradient(120deg, var(--accent), var(--accent-3) 60%, var(--accent-2));
  background-clip: text; -webkit-background-clip: text; color: transparent; }
.subtitle { font-size: clamp(1.05rem, 1.6vw, 1.35rem); color: var(--text-dim);
  max-width: 60ch; margin: 0 0 36px; line-height: 1.55; }
.hero-cta { display: flex; gap: 14px; flex-wrap: wrap; margin-bottom: 50px; }
.btn { display: inline-block; padding: 12px 22px; border-radius: 999px;
  font-family: var(--ff-mono); font-size: 13px; font-weight: 600;
  letter-spacing: 0.04em; text-transform: uppercase; border: 1px solid var(--line);
  transition: transform 0.15s, background 0.15s; }
.btn.primary { background: var(--accent); color: #1a0d09; border-color: var(--accent); }
.btn.primary:hover { transform: translateY(-1px); background: #ffa68a; }
.btn.ghost { background: transparent; color: var(--text); }
.btn.ghost:hover { background: rgba(255,255,255,0.06); color: var(--accent); border-color: var(--accent); }
.hero-meta { font-size: 13.5px; color: var(--text-muted); max-width: 50ch; font-style: italic; }

/* ===== SECTIONS / PROSE ===== */
section { padding: 100px var(--gutter); border-bottom: 1px solid var(--line-soft); }
.prose { max-width: var(--measure); margin: 0 auto; }
.section-kicker { font-family: var(--ff-mono); font-size: 12px;
  color: var(--accent); letter-spacing: 0.14em;
  text-transform: uppercase; margin: 0 0 8px; }

.callout { margin: 2em 0; padding: 18px 22px; background: var(--bg-card);
  border-left: 3px solid var(--accent); border-radius: 8px;
  font-size: 0.96em; color: var(--text-dim); }
.callout.subtle { border-left-color: var(--accent-4); }
.callout strong { color: var(--accent); }

.math-block { margin: 1.6em 0; padding: 18px; background: var(--bg-card);
  border: 1px solid var(--line); border-radius: var(--radius);
  font-size: 1.05em; overflow-x: auto; text-align: center; }
.katex-display { margin: 0 !important; }

.viz-block { margin: 2em 0; padding: 24px; background: var(--bg-card);
  border: 1px solid var(--line); border-radius: var(--radius); }
.viz-block.big { padding: 28px; }
.viz-header h4 { margin: 0 0 4px; color: var(--accent);
  font-family: var(--ff-mono); font-weight: 700;
  letter-spacing: 0.06em; text-transform: uppercase; font-size: 12px; }
.viz-header p { margin: 0 0 16px; font-size: 0.95em; color: var(--text-dim); }
.viz-block canvas { display: block; width: 100%; max-width: 100%; height: auto;
  border-radius: 10px; background: var(--bg-deep);
  cursor: crosshair; touch-action: none; }
.viz-readout { margin-top: 12px; font-family: var(--ff-mono); font-size: 12.5px;
  color: var(--text-dim); background: var(--bg-deep);
  padding: 8px 12px; border-radius: 6px; white-space: pre; overflow-x: auto; }
.viz-controls { margin-top: 14px; display: flex; gap: 16px;
  align-items: center; flex-wrap: wrap;
  font-family: var(--ff-mono); font-size: 12.5px; color: var(--text-dim); }
.viz-controls input[type="range"] { flex: 1; min-width: 180px; accent-color: var(--accent); }
.viz-controls button { background: var(--bg-deep); color: var(--text);
  border: 1px solid var(--line); padding: 6px 14px; border-radius: 6px;
  font-family: var(--ff-mono); font-size: 12px; cursor: pointer;
  text-transform: uppercase; letter-spacing: 0.06em; }
.viz-controls button:hover { background: var(--accent); color: #1a0d09; border-color: var(--accent); }
.viz-controls label { display: flex; gap: 8px; align-items: center; flex: 1; min-width: 160px; }

.pipeline-list { counter-reset: step; list-style: none; padding: 0; margin: 2em 0; }
.pipeline-list li { counter-increment: step; position: relative;
  padding: 14px 16px 14px 60px; background: var(--bg-card);
  border: 1px solid var(--line); border-radius: 10px; margin: 8px 0; }
.pipeline-list li::before { content: counter(step);
  position: absolute; left: 16px; top: 50%; transform: translateY(-50%);
  width: 32px; height: 32px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  background: var(--accent); color: #1a0d09;
  font-family: var(--ff-mono); font-weight: 700; font-size: 14px; }

.stat-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 14px; margin: 2em 0; }
.stat { background: var(--bg-card); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 22px 20px; }
.stat-num { font-family: var(--ff-display); font-size: 2.6rem; font-weight: 700;
  color: var(--accent); line-height: 1.05; }
.stat-num small { font-size: 0.45em; color: var(--text-dim); margin-left: 4px;
  font-weight: 500; font-family: var(--ff-mono); letter-spacing: 0.04em; }
.stat-lbl { font-size: 13px; color: var(--text-dim); margin-top: 8px; line-height: 1.4; }

.timeline-section { padding-bottom: 60px;
  background: radial-gradient(ellipse at top, rgba(255,138,106,0.06), transparent 60%), var(--bg); }
.timeline-wrap { max-width: 1100px; margin: 40px auto 0; padding: 0 var(--gutter);
  display: grid; grid-template-columns: 1fr 1.1fr; gap: 40px; align-items: start; }
#timeline-rail { position: relative; border-left: 2px solid var(--line); padding: 0; }
.tl-item { position: relative; padding: 14px 16px 14px 32px;
  cursor: pointer; border-radius: 8px; margin-left: -2px;
  transition: background 0.15s, border-left-color 0.15s;
  border-left: 2px solid transparent; }
.tl-item:hover { background: var(--bg-card); }
.tl-item.active { background: var(--bg-card); border-left-color: var(--accent); }
.tl-item::before { content: ''; position: absolute; left: -8px; top: 22px;
  width: 12px; height: 12px; border-radius: 50%;
  background: var(--bg); border: 2px solid var(--line); }
.tl-item.active::before { background: var(--accent); border-color: var(--accent);
  box-shadow: 0 0 0 4px rgba(255,138,106,0.18); }
.tl-year { font-family: var(--ff-mono); font-size: 11px; letter-spacing: 0.1em; color: var(--accent); text-transform: uppercase; }
.tl-title { font-family: var(--ff-display); font-weight: 600; font-size: 1.05rem; color: #fff; margin: 2px 0; }
.tl-tag { font-family: var(--ff-mono); font-size: 11px; color: var(--text-dim); }
#timeline-detail { position: sticky; top: calc(var(--nav-h) + 20px);
  background: var(--bg-card); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 30px; min-height: 360px; }
#timeline-detail h3 { margin-top: 0; color: var(--accent); }
.td-meta { font-family: var(--ff-mono); font-size: 12px; color: var(--text-dim);
  margin-bottom: 18px; border-bottom: 1px dashed var(--line); padding-bottom: 14px; }
.td-meta span { display: inline-block; margin-right: 14px; }
.td-meta b { color: var(--accent-2); }

.cmp-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin: 2em 0; }
.cmp { background: var(--bg-card); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 20px; }
.cmp h4 { margin: 0 0 10px; color: var(--accent);
  font-family: var(--ff-mono); font-size: 12px;
  letter-spacing: 0.08em; text-transform: uppercase; }
.cmp.alt h4 { color: var(--accent-3); }
.cmp p { font-size: 0.95em; color: var(--text-dim); margin: 0 0 0.7em; }
.cmp ul { padding-left: 1.2em; font-size: 0.93em; color: var(--text-dim); }

.deepdive { padding-top: 60px; padding-bottom: 60px;
  border-bottom: 1px dashed var(--line-soft); }
.dd-meta { font-family: var(--ff-mono); font-size: 12.5px;
  color: var(--text-muted); margin: -8px 0 14px; }

footer { padding: 80px var(--gutter); background: var(--bg-deep);
  border-top: 1px solid var(--line); }
footer h3 { color: var(--accent); }
.refs { list-style: none; padding: 0; }
.refs li { padding: 6px 0; border-bottom: 1px solid var(--line-soft); }
.footer-meta { margin-top: 30px; font-size: 13px; color: var(--text-muted); }

@media (max-width: 760px) {
  body { font-size: 16px; }
  section { padding: 60px var(--gutter); }
  .hero { padding: 90px var(--gutter) 60px; }
  #navtoggle { display: block; }
  #navlinks { display: none; position: absolute; top: var(--nav-h);
    right: 0; left: 0; flex-direction: column; background: var(--bg-soft);
    padding: 14px var(--gutter); border-bottom: 1px solid var(--line); }
  #navlinks.open { display: flex; }
  .timeline-wrap { grid-template-columns: 1fr; }
  #timeline-detail { position: static; }
  .cmp-grid { grid-template-columns: 1fr; }
  #lang-toggle { margin-left: 8px; padding: 4px 8px; font-size: 10px; }
}

/* ===== LANG TOGGLE ===== */
#lang-toggle {
  background: transparent;
  color: var(--text-dim);
  border: 1px solid var(--line);
  padding: 5px 11px;
  border-radius: 6px;
  font-family: var(--ff-mono);
  font-size: 11px;
  cursor: pointer;
  letter-spacing: 0.08em;
  margin-left: 14px;
  flex-shrink: 0;
  transition: color 0.15s, border-color 0.15s;
}
#lang-toggle:hover { color: var(--accent); border-color: var(--accent); }
[lang="zh"] { display: none; }
html[data-lang="zh"] [lang="en"] { display: none; }
html[data-lang="zh"] [lang="zh"] { display: revert; }