/* ============================================================
   Minimalist Monochrome — pure black & white, serif hero,
   oversized type, zero radius, line-based, editorial luxury.
   ============================================================ */

:root {
  --bg: #ffffff;
  --fg: #000000;
  --muted: #f5f5f5;
  --muted-fg: #525252;
  --border: #000000;
  --border-light: #e5e5e5;

  --display: "Playfair Display", "Songti SC", "Songti TC", "SimSun", Georgia, serif;
  --body: "Source Serif 4", "Songti SC", "SimSun", Georgia, serif;
  --mono: "JetBrains Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; border-radius: 0 !important; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--body);
  font-size: 18px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  position: relative;
}

/* paper-quality line texture, globally, almost invisible */
body::before {
  content: "";
  position: fixed; inset: 0; z-index: -1; pointer-events: none;
  background-image: repeating-linear-gradient(0deg, transparent, transparent 1px, #000 1px, #000 2px);
  background-size: 100% 4px;
  opacity: 0.015;
}

.wrap { max-width: 1100px; margin: 0 auto; padding: 0 28px; }
.reading { max-width: 760px; }

/* ---------- selection ---------- */
::selection { background: #000; color: #fff; }

/* ---------- links ---------- */
a { color: var(--fg); text-decoration: none; }
.article a, .prose a { border-bottom: 1px solid var(--fg); }
.article a:hover, .prose a:hover { background: var(--fg); color: var(--bg); }

/* ---------- icons ---------- */
.icon { width: 20px; height: 20px; stroke: currentColor; fill: none; stroke-width: 1.5; stroke-linecap: square; stroke-linejoin: miter; vertical-align: middle; display: inline-block; }
.icon-sq { width: 22px; height: 22px; }

/* ---------- nav ---------- */
.nav {
  display: flex; align-items: center; justify-content: space-between;
  padding: 26px 0; border-bottom: 1px solid var(--border);
}
.nav .brand { display: flex; align-items: center; gap: 12px; }
.nav .brand .mark { width: 26px; height: 26px; border: 2px solid var(--fg); position: relative; flex: none; }
.nav .brand .mark::after { content: ""; position: absolute; left: 0; right: 0; top: 50%; height: 3px; background: var(--fg); transform: translateY(-50%); }
.nav .name { font-family: var(--mono); font-size: 13px; letter-spacing: .16em; text-transform: uppercase; color: var(--fg); }
.nav .links { display: flex; gap: 26px; align-items: center; }
.nav .links a { font-family: var(--mono); font-size: 12px; letter-spacing: .12em; text-transform: uppercase; color: var(--fg); display: inline-flex; align-items: center; gap: 6px; padding: 4px 0; }
.nav .links a:hover { border-bottom: 2px solid var(--fg); margin-bottom: -2px; }

/* ---------- rules ---------- */
.rule { height: 4px; background: var(--fg); border: 0; margin: 0; }
.rule-thin { height: 1px; background: var(--fg); border: 0; }
.punct { display: flex; align-items: center; gap: 0; margin: 0 0 30px; }
.punct .bar { height: 4px; background: var(--fg); flex: 1; }
.punct .box { width: 16px; height: 16px; border: 2px solid var(--fg); margin-left: 10px; flex: none; }

/* ---------- hero ---------- */
.hero { padding: 84px 0 20px; }
.hero .kicker { font-family: var(--mono); font-size: 12px; letter-spacing: .22em; text-transform: uppercase; color: var(--fg); margin: 0 0 30px; }
.hero h1 {
  font-family: var(--display); font-weight: 800;
  font-size: clamp(2.2rem, 6vw, 4rem); line-height: 1.05;
  letter-spacing: -0.02em; margin: 0 0 30px;
}
.hero h1 .en { display: block; font-size: clamp(1rem, 2.4vw, 1.6rem); font-family: var(--mono); font-weight: 400; letter-spacing: .1em; text-transform: uppercase; color: var(--muted-fg); margin-top: 22px; }
.hero .lead { max-width: 720px; font-size: 20px; line-height: 1.6; margin: 0 0 16px; }
.hero .lead.small { font-size: 17px; color: var(--muted-fg); }

/* ---------- sections ---------- */
section { padding: 64px 0; }
section + section { border-top: 4px solid var(--fg); }
.sec-label { font-family: var(--mono); font-size: 12px; letter-spacing: .2em; text-transform: uppercase; color: var(--muted-fg); margin: 0 0 34px; display: flex; align-items: center; gap: 14px; }
.sec-label::after { content: ""; height: 1px; background: var(--border-light); flex: 1; }

/* ---------- inverted block (pull quote / statement) ---------- */
.invert {
  background: var(--fg); color: var(--bg);
  padding: 64px 48px; position: relative; overflow: hidden;
}
.invert::before {
  content: ""; position: absolute; inset: 0; pointer-events: none;
  background-image: repeating-linear-gradient(90deg, transparent, transparent 1px, #fff 1px, #fff 2px);
  background-size: 4px 100%; opacity: 0.04;
}
.invert .q { font-family: var(--display); font-style: italic; font-size: clamp(1.6rem, 4vw, 2.6rem); line-height: 1.3; margin: 0; position: relative; }
.invert .q .mark { font-size: 3em; line-height: 0; vertical-align: -0.4em; margin-right: 8px; }
.invert .attr { font-family: var(--mono); font-size: 12px; letter-spacing: .14em; text-transform: uppercase; color: #bbb; margin-top: 26px; }

/* ---------- items / cards ---------- */
.item {
  display: block; padding: 30px 28px; text-decoration: none;
  border: 1px solid var(--fg); border-top: 0;
  transition: background 100ms, color 100ms;
}
.list .item:first-child { border-top: 1px solid var(--fg); }
.item:hover { background: var(--fg); color: var(--bg); }
.item .head { display: flex; align-items: baseline; justify-content: space-between; gap: 16px; }
.item .t { font-family: var(--display); font-weight: 700; font-size: 26px; line-height: 1.1; letter-spacing: -0.01em; }
.item .arrow { font-family: var(--mono); font-size: 20px; flex: none; opacity: 0; transform: translateX(-6px); transition: opacity 100ms, transform 100ms; }
.item:hover .arrow { opacity: 1; transform: translateX(0); }
.item .d { font-size: 16.5px; line-height: 1.55; margin-top: 12px; color: var(--muted-fg); }
.item:hover .d { color: #cfcfcf; }
.item .ic { display: flex; align-items: center; gap: 14px; margin-bottom: 14px; }
.item .ic .badge { width: 40px; height: 40px; border: 1.5px solid currentColor; display: flex; align-items: center; justify-content: center; flex: none; }
.item .ic .badge .icon { width: 22px; height: 22px; }
.item .ic .osrc { font-family: var(--mono); font-size: 11px; letter-spacing: .12em; text-transform: uppercase; border: 1px solid currentColor; padding: 2px 7px; }

/* ---------- prose (landing meta) ---------- */
.prose p { max-width: 720px; }
.prose .meta { color: var(--muted-fg); font-size: 16.5px; }

/* ---------- article ---------- */
.article { padding: 60px 0 0; }
.article .kicker { font-family: var(--mono); font-size: 12px; letter-spacing: .2em; text-transform: uppercase; color: var(--fg); margin: 0 0 26px; }
.article h1 { font-family: var(--display); font-weight: 800; font-size: clamp(1.8rem, 4.2vw, 2.9rem); line-height: 1.15; letter-spacing: -0.015em; margin: 0 0 16px; }
.article .sub { font-family: var(--display); font-style: italic; font-size: clamp(1.15rem, 2.6vw, 1.7rem); color: var(--fg); margin: 0 0 6px; }
.article .part {
  font-family: var(--mono); font-size: 13px; letter-spacing: .18em; text-transform: uppercase;
  margin: 70px 0 30px; padding: 16px 0; border-top: 4px solid var(--fg); border-bottom: 4px solid var(--fg);
}
.article h3 { font-family: var(--display); font-weight: 700; font-size: 26px; line-height: 1.15; letter-spacing: -0.01em; margin: 46px 0 14px; }
.article h3 .bk { vertical-align: middle; }
.article p { margin: 0 0 18px; }
.article ul, .article ol { margin: 0 0 20px; padding-left: 0; list-style: none; }
.article li { margin: 0 0 12px; padding-left: 26px; position: relative; }
.article ul li::before { content: ""; position: absolute; left: 0; top: 0.62em; width: 12px; height: 1.5px; background: var(--fg); }
.article ol { counter-reset: n; }
.article ol li { counter-increment: n; }
.article ol li::before { content: counter(n); position: absolute; left: 0; top: 0; font-family: var(--mono); font-size: 13px; font-weight: 700; line-height: 1.9; }
.article strong { font-weight: 700; }
.article em { font-style: italic; }
.article code { font-family: var(--mono); font-size: 0.84em; background: var(--muted); padding: 1px 5px; border: 1px solid var(--border-light); }

/* boxed drop cap on first paragraph after .lede-anchor */
.dropcap::first-letter {
  float: left; font-family: var(--display); font-weight: 800;
  font-size: 4.6rem; line-height: 0.72; margin: 6px 16px 0 0; padding: 12px 14px;
  border: 2px solid var(--fg);
}

/* bucket tags — monochrome, distinguished by fill vs outline */
.bk { font-family: var(--mono); font-size: 10.5px; letter-spacing: .06em; text-transform: uppercase; padding: 2px 7px; margin-left: 8px; font-weight: 600; white-space: nowrap; position: relative; top: -2px; }
.bk.solid { background: var(--fg); color: var(--bg); }          /* 已上线 */
.bk.open  { background: var(--bg); color: var(--fg); border: 1px solid var(--fg); }  /* 创新·未验 */

/* diagram */
.diagram {
  font-family: var(--mono); font-size: 12px; line-height: 1.45;
  background: var(--bg); border: 2px solid var(--fg);
  padding: 22px; overflow-x: auto; color: var(--fg); margin: 0 0 14px; white-space: pre;
}
figure { margin: 30px 0; }
figcaption { font-family: var(--mono); font-size: 12px; letter-spacing: .08em; text-transform: uppercase; color: var(--muted-fg); margin-top: 12px; }

/* note callout */
.note { border: 1px solid var(--fg); padding: 22px 26px; margin: 0 0 24px; font-size: 16.5px; }
.note.dark { background: var(--fg); color: var(--bg); border: 0; }
.note .label { font-family: var(--mono); font-size: 11px; letter-spacing: .14em; text-transform: uppercase; display: block; margin-bottom: 10px; color: var(--muted-fg); }
.note.dark .label { color: #bbb; }
.note.dark code { background: #222; border-color: #333; color: #eee; }

.meta-line { color: var(--muted-fg); font-size: 15.5px; }

/* ---------- footer ---------- */
footer { padding: 48px 0 70px; border-top: 4px solid var(--fg); margin-top: 20px; }
footer .row { display: flex; align-items: center; gap: 20px; flex-wrap: wrap; font-family: var(--mono); font-size: 12px; letter-spacing: .1em; text-transform: uppercase; color: var(--muted-fg); }
footer a { color: var(--fg); display: inline-flex; align-items: center; gap: 7px; }
footer a:hover { border-bottom: 2px solid var(--fg); }
footer .fine { margin-top: 16px; font-family: var(--mono); font-size: 11px; letter-spacing: .06em; color: var(--muted-fg); text-transform: none; }

.backlink { font-family: var(--mono); font-size: 12px; letter-spacing: .12em; text-transform: uppercase; margin: 56px 0 0; }
.backlink a { border-bottom: 1px solid var(--fg); }
.backlink a:hover { background: var(--fg); color: var(--bg); }

/* ---------- focus (a11y) ---------- */
a:focus-visible, button:focus-visible { outline: 3px solid var(--fg); outline-offset: 3px; }

/* ---------- responsive ---------- */
@media (max-width: 720px) {
  body { font-size: 17px; }
  .nav .links { gap: 16px; }
  .nav .links a span.lbl { display: none; }
  .invert { padding: 44px 26px; }
  .item { padding: 24px 20px; }
  .diagram { font-size: 10px; padding: 16px; }
  .dropcap::first-letter { font-size: 3.4rem; }
}

/* ---------- mermaid ---------- */
.mermaid { text-align: center; margin: 6px 0; overflow-x: auto; font-family: var(--mono); background: var(--bg); border: 2px solid var(--fg); padding: 20px; }
.mermaid svg { max-width: 100%; height: auto; }

/* ---------- figure placeholder slot (screenshots to be dropped in) ---------- */
.slot-box {
  border: 2px dashed var(--fg); background: var(--muted);
  min-height: 150px; display: flex; align-items: center; justify-content: center;
  text-align: center; padding: 28px; font-family: var(--mono); font-size: 12.5px;
  letter-spacing: .03em; color: var(--muted-fg); line-height: 1.7;
}

/* ---------- data table (experiments / ablation) ---------- */
table.data { width: 100%; border-collapse: collapse; margin: 4px 0 22px; font-size: 15px; }
table.data th, table.data td { border: 1px solid var(--fg); padding: 9px 12px; text-align: left; vertical-align: top; }
table.data th { font-family: var(--mono); font-size: 11px; letter-spacing: .07em; text-transform: uppercase; background: var(--fg); color: var(--bg); font-weight: 600; }
table.data td code { background: var(--muted); }
table.data tr:hover td { background: var(--muted); }

/* ---------- project card thumbnails ---------- */
.item .shot { width: 100%; aspect-ratio: 16 / 9; object-fit: cover; object-position: top center; border: 1px solid var(--fg); display: block; margin: 0 0 16px; background: var(--muted); }
.item:hover .shot { filter: grayscale(0); }
.item .link { font-family: var(--mono); font-size: 11px; letter-spacing: .1em; text-transform: uppercase; color: var(--muted-fg); margin-top: 10px; display: inline-block; }
.item:hover .link { color: #cfcfcf; }