/* ============================================================
   AIDC — Design System
   "Institutional Precision" — 黑白体系 + 单一信号色
   Brand: `//` slash family (wider gap + clipped ends)
   Type:  Archivo (display/body) + IBM Plex Mono (labels/code)
   ============================================================ */

:root {
  /* palette — dark (marketing default) */
  --bg: #0b0b0c;
  --bg-2: #101013;
  --bg-3: #16161a;
  --ink: #ece9e1;
  --ink-strong: #fffdf7;
  --mut: #8f8c84;
  --mut-2: #66645e;
  --line: rgba(236, 233, 225, 0.13);
  --line-soft: rgba(236, 233, 225, 0.07);
  --signal: #ff4d00;
  --signal-soft: rgba(255, 77, 0, 0.12);
  --signal-hover: #ff6b2e;

  /* type */
  --font-display: "Archivo", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Archivo", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: "IBM Plex Mono", "SFMono-Regular", Consolas, monospace;

  /* scale */
  --w-max: 1280px;
  --pad-x: clamp(20px, 4vw, 56px);
  --nav-h: 64px;
  --radius: 2px;
}

/* light theme (docs) */
[data-theme="light"] {
  --bg: #f7f5f0;
  --bg-2: #f0eee7;
  --bg-3: #e9e6dd;
  --ink: #1a1916;
  --ink-strong: #0b0b0a;
  --mut: #6f6c64;
  --mut-2: #98948a;
  --line: rgba(26, 25, 22, 0.14);
  --line-soft: rgba(26, 25, 22, 0.07);
  --signal: #e34400;
  --signal-soft: rgba(227, 68, 0, 0.09);
  --signal-hover: #ff4d00;
}

/* ---------- base ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.7;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
::selection { background: var(--signal); color: #0b0b0c; }

img, svg { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
p a, li a, td a {
  color: var(--ink-strong);
  border-bottom: 1px solid var(--signal);
  transition: color .15s, background .15s;
}
p a:hover, li a:hover, td a:hover { color: var(--signal); }

h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--ink-strong);
  font-weight: 700;
  line-height: 1.12;
  letter-spacing: -0.015em;
  margin: 0 0 0.5em;
}
h1 { font-size: clamp(2.4rem, 5.4vw, 4.4rem); font-weight: 800; letter-spacing: -0.03em; }
h2 { font-size: clamp(1.7rem, 3.2vw, 2.6rem); letter-spacing: -0.02em; }
h3 { font-size: 1.25rem; }
h4 { font-size: 1.02rem; }
p { margin: 0 0 1em; }
strong { color: var(--ink-strong); font-weight: 600; }
hr { border: 0; border-top: 1px solid var(--line); margin: 2.5rem 0; }

code {
  font-family: var(--font-mono);
  font-size: 0.86em;
  background: var(--bg-3);
  border: 1px solid var(--line-soft);
  padding: 0.1em 0.4em;
  border-radius: var(--radius);
  color: var(--ink-strong);
}
pre {
  background: var(--bg-2);
  border: 1px solid var(--line);
  border-left: 2px solid var(--signal);
  padding: 1.1rem 1.3rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.84rem;
  line-height: 1.65;
  margin: 1.4rem 0;
}
pre code { background: none; border: 0; padding: 0; font-size: inherit; }

/* ---------- the // mark ---------- */
.mark {
  display: inline-flex;
  align-items: center;
  gap: 0.30em;          /* wider gap — brand rule */
  height: 1em;
  flex: none;
}
.mark i {
  display: block;
  width: 0.26em;
  height: 1em;
  background: currentColor;
  transform: skewX(-20deg);   /* clipped ends — parallelogram */
}
.mark--signal i { background: var(--signal); }

/* ---------- kicker label ---------- */
.kicker {
  display: flex;
  align-items: center;
  gap: 0.8em;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 500;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--mut);
  margin-bottom: 1.6rem;
}
.kicker::before {
  content: "";
  display: inline-block;
  width: 7px; height: 13px;
  background:
    linear-gradient(currentColor, currentColor) left/2px 100% no-repeat,
    linear-gradient(currentColor, currentColor) right/2px 100% no-repeat;
  transform: skewX(-20deg);
  color: var(--signal);
}
.kicker .num { color: var(--signal); }

/* ---------- layout ---------- */
.wrap {
  max-width: var(--w-max);
  margin: 0 auto;
  padding: 0 var(--pad-x);
}
.sec { padding: clamp(72px, 10vw, 140px) 0; position: relative; }
.sec + .sec { border-top: 1px solid var(--line-soft); }
.sec-head { max-width: 720px; margin-bottom: clamp(40px, 5vw, 64px); }
.sec-head .lede { font-size: 1.12rem; color: var(--mut); margin-top: 1.2rem; }
.lede { font-size: 1.15rem; line-height: 1.75; color: var(--mut); }
.en-sub {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.04em;
  color: var(--mut-2);
  margin-top: 0.9rem;
  line-height: 1.7;
}

/* ---------- top navigation ---------- */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  border-bottom: 1px solid var(--line-soft);
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: blur(14px) saturate(1.1);
  -webkit-backdrop-filter: blur(14px) saturate(1.1);
}
.nav-inner {
  width: 100%;
  max-width: var(--w-max);
  margin: 0 auto;
  padding: 0 var(--pad-x);
  display: flex;
  align-items: center;
  gap: 2.5rem;
}
.nav-logo {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.05rem;
  letter-spacing: 0.06em;
  color: var(--ink-strong);
}
.nav-logo .mark { font-size: 0.95rem; color: var(--signal); }
.nav-links {
  display: flex;
  gap: 1.8rem;
  margin-left: auto;
  align-items: center;
}
.nav-links a {
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  color: var(--mut);
  transition: color .15s;
  padding: 0.4rem 0;
}
.nav-links a:hover { color: var(--ink-strong); }
.nav-links a.active { color: var(--ink-strong); position: relative; }
.nav-links a.active::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: -2px;
  height: 2px;
  background: var(--signal);
}
.nav-cta {
  font-family: var(--font-mono);
  font-size: 0.72rem !important;
  letter-spacing: 0.1em !important;
  text-transform: uppercase;
  color: var(--ink-strong) !important;
  border: 1px solid var(--line);
  padding: 0.55rem 1.1rem !important;
  transition: border-color .15s, background .15s, color .15s !important;
}
.nav-cta:hover { border-color: var(--signal); color: var(--signal) !important; }
.nav-burger {
  display: none;
  margin-left: auto;
  background: none;
  border: 1px solid var(--line);
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  padding: 0.5rem 0.9rem;
  cursor: pointer;
}
body { padding-top: var(--nav-h); }

/* ---------- buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.7em;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 0.95rem 1.7rem;
  border: 1px solid var(--line);
  color: var(--ink-strong);
  background: transparent;
  cursor: pointer;
  transition: border-color .18s, background .18s, color .18s, transform .18s;
}
.btn:hover { border-color: var(--signal); color: var(--signal); }
.btn--primary {
  background: var(--signal);
  border-color: var(--signal);
  color: #0b0b0c;
}
.btn--primary:hover { background: var(--signal-hover); border-color: var(--signal-hover); color: #0b0b0c; }
.btn .arr { font-family: var(--font-mono); transition: transform .18s; }
.btn:hover .arr { transform: translateX(4px); }
.btn-row { display: flex; gap: 1rem; flex-wrap: wrap; }

/* ---------- hero ---------- */
.hero {
  position: relative;
  min-height: calc(92vh - var(--nav-h));
  display: flex;
  align-items: center;
  overflow: hidden;
}
.hero-inner { position: relative; z-index: 2; padding: clamp(60px, 8vw, 110px) 0; max-width: 880px; }
.hero h1 .accent { color: var(--signal); }
.hero .lede { max-width: 620px; margin-top: 1.6rem; font-size: 1.18rem; }
.hero .btn-row { margin-top: 2.6rem; }

/* giant background slashes */
.hero-slashes {
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  overflow: hidden;
}
.hero-slashes::before,
.hero-slashes::after {
  content: "";
  position: absolute;
  top: -12%;
  height: 124%;
  width: clamp(90px, 11vw, 170px);
  background: linear-gradient(180deg, var(--signal-soft), rgba(255,77,0,0.02));
  transform: skewX(-20deg);
}
.hero-slashes::before { right: clamp(180px, 24vw, 420px); }
.hero-slashes::after { right: clamp(40px, 10vw, 190px); }

/* engineering grid backdrop */
.grid-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    linear-gradient(var(--line-soft) 1px, transparent 1px),
    linear-gradient(90deg, var(--line-soft) 1px, transparent 1px);
  background-size: 72px 72px;
  -webkit-mask-image: radial-gradient(ellipse 90% 80% at 50% 0%, #000 30%, transparent 75%);
  mask-image: radial-gradient(ellipse 90% 80% at 50% 0%, #000 30%, transparent 75%);
}

/* ---------- stat strip ---------- */
.stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  border: 1px solid var(--line);
  border-width: 1px 0;
}
.stat {
  padding: 2rem var(--pad-x) 2rem 0;
  border-right: 1px solid var(--line-soft);
  padding-left: 1.6rem;
}
.stat:last-child { border-right: 0; }
.stat .n {
  font-family: var(--font-display);
  font-size: clamp(2rem, 3.4vw, 2.9rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--ink-strong);
}
.stat .n em { font-style: normal; color: var(--signal); }
.stat .l {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--mut);
  margin-top: 0.4rem;
}

/* ---------- cards ---------- */
.cards {
  display: grid;
  gap: 1px;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
}
.cards--2 { grid-template-columns: repeat(2, 1fr); }
.cards--3 { grid-template-columns: repeat(3, 1fr); }
.cards--4 { grid-template-columns: repeat(4, 1fr); }
.card {
  background: var(--bg);
  padding: 2rem 1.8rem 2.2rem;
  position: relative;
  transition: background .25s;
}
.card:hover { background: var(--bg-2); }
.card .idx {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.16em;
  color: var(--signal);
  display: block;
  margin-bottom: 1.6rem;
}
.card h3 { margin-bottom: 0.7rem; }
.card p { color: var(--mut); font-size: 0.93rem; margin: 0; }
.card .card-link {
  display: inline-flex;
  align-items: center;
  gap: 0.5em;
  margin-top: 1.4rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-strong);
}
.card .card-link::after { content: "→"; transition: transform .18s; color: var(--signal); }
.card:hover .card-link::after { transform: translateX(4px); }
.card--flag::before {
  content: "";
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 2px;
  background: var(--signal);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform .3s;
}
.card:hover.card--flag::before { transform: scaleX(1); }

/* ---------- split layout ---------- */
.split {
  display: grid;
  grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  gap: clamp(40px, 6vw, 96px);
  align-items: start;
}
.split--rev { grid-template-columns: minmax(0, 7fr) minmax(0, 5fr); }
.split .sticky { position: sticky; top: calc(var(--nav-h) + 32px); }

/* ---------- numbered list (institutional) ---------- */
.numlist { list-style: none; margin: 0; padding: 0; counter-reset: nl; }
.numlist > li {
  counter-increment: nl;
  display: grid;
  grid-template-columns: 64px 1fr;
  gap: 1.4rem;
  padding: 1.6rem 0;
  border-top: 1px solid var(--line-soft);
}
.numlist > li::before {
  content: counter(nl, decimal-leading-zero);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--signal);
  padding-top: 0.2rem;
}
.numlist h4 { margin-bottom: 0.4rem; }
.numlist p { color: var(--mut); font-size: 0.93rem; margin: 0; }

/* ---------- tables ---------- */
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
  margin: 1.5rem 0;
}
th {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--mut);
  text-align: left;
  padding: 0.8rem 1rem;
  border-bottom: 1px solid var(--line);
}
td {
  padding: 0.85rem 1rem;
  border-bottom: 1px solid var(--line-soft);
  vertical-align: top;
  color: var(--ink);
}
td:first-child { color: var(--ink-strong); font-weight: 500; }
tr:hover td { background: var(--bg-2); }

/* ---------- figure / diagram shell ---------- */
.figure {
  border: 1px solid var(--line);
  background: var(--bg-2);
  padding: clamp(20px, 3vw, 40px);
  margin: 2rem 0;
  position: relative;
}
.figure .fig-label {
  position: absolute;
  top: 0; left: 0;
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--mut);
  background: var(--bg);
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  padding: 0.45rem 0.9rem;
}
.figure figcaption {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  color: var(--mut);
  margin-top: 1.4rem;
  letter-spacing: 0.03em;
  line-height: 1.7;
}

/* stacked architecture layers */
.layers { display: flex; flex-direction: column; gap: 6px; margin-top: 1.5rem; }
.layer {
  display: grid;
  grid-template-columns: 56px 1fr auto;
  align-items: center;
  gap: 1.2rem;
  border: 1px solid var(--line);
  background: var(--bg);
  padding: 1rem 1.3rem;
  transition: border-color .2s, transform .2s, background .2s;
}
.layer:hover { border-color: var(--signal); background: var(--bg-2); transform: translateX(6px); }
.layer .ln {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--signal);
  letter-spacing: 0.1em;
}
.layer .lt { font-weight: 600; color: var(--ink-strong); font-size: 0.95rem; }
.layer .ld {
  font-size: 0.8rem;
  color: var(--mut);
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
  text-align: right;
}

/* ---------- big quote / thesis ---------- */
.thesis {
  font-family: var(--font-display);
  font-size: clamp(1.5rem, 3.2vw, 2.4rem);
  font-weight: 600;
  line-height: 1.35;
  letter-spacing: -0.015em;
  color: var(--ink-strong);
  max-width: 900px;
}
.thesis .accent { color: var(--signal); }
.thesis-src {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--mut);
  margin-top: 2rem;
}

/* ---------- footer ---------- */
.footer {
  border-top: 1px solid var(--line);
  padding: clamp(48px, 6vw, 80px) 0 40px;
  background: var(--bg);
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 2.5rem;
  margin-bottom: 3.5rem;
}
.footer-brand .nav-logo { margin-bottom: 1.2rem; }
.footer-brand p { color: var(--mut); font-size: 0.88rem; max-width: 320px; }
.footer h5 {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--mut);
  margin: 0 0 1.1rem;
}
.footer ul { list-style: none; margin: 0; padding: 0; }
.footer ul li { margin-bottom: 0.65rem; }
.footer ul a { font-size: 0.88rem; color: var(--ink); transition: color .15s; }
.footer ul a:hover { color: var(--signal); }
.footer-base {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1.5rem;
  flex-wrap: wrap;
  border-top: 1px solid var(--line-soft);
  padding-top: 1.8rem;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  color: var(--mut-2);
}

/* ---------- CTA band ---------- */
.cta-band {
  border-top: 1px solid var(--line);
  background:
    linear-gradient(180deg, var(--bg), var(--bg-2));
  position: relative;
  overflow: hidden;
}
.cta-band .hero-slashes::before { right: 12%; }
.cta-band .hero-slashes::after { right: 4%; }
.cta-band .inner { position: relative; z-index: 1; padding: clamp(70px, 9vw, 120px) 0; max-width: 760px; }

/* ---------- reveal animations ---------- */
@media (prefers-reduced-motion: no-preference) {
  .reveal {
    opacity: 0;
    transform: translateY(26px);
    transition: opacity .8s cubic-bezier(.16,1,.3,1), transform .8s cubic-bezier(.16,1,.3,1);
  }
  .reveal.is-in { opacity: 1; transform: none; }
  .reveal[data-d="1"] { transition-delay: .08s; }
  .reveal[data-d="2"] { transition-delay: .16s; }
  .reveal[data-d="3"] { transition-delay: .24s; }
  .reveal[data-d="4"] { transition-delay: .32s; }
  .hero .reveal { transition-duration: 1s; }
}

/* grain overlay */
body::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 999;
  pointer-events: none;
  opacity: 0.05;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='128' height='128'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2'/%3E%3C/filter%3E%3Crect width='128' height='128' filter='url(%23n)' opacity='1'/%3E%3C/svg%3E");
}

/* ---------- responsive ---------- */
@media (max-width: 980px) {
  .cards--3, .cards--4 { grid-template-columns: repeat(2, 1fr); }
  .split, .split--rev { grid-template-columns: 1fr; }
  .split .sticky { position: static; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 720px) {
  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-h);
    left: 0; right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--line);
    padding: 0.5rem var(--pad-x) 1.2rem;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 0.8rem 0; border-bottom: 1px solid var(--line-soft); }
  .nav-cta { border: 0; padding-left: 0 !important; }
  .nav-burger { display: block; }
  .cards--2, .cards--3, .cards--4 { grid-template-columns: 1fr; }
  .layer { grid-template-columns: 42px 1fr; }
  .layer .ld { display: none; }
  .footer-grid { grid-template-columns: 1fr; }
  .numlist > li { grid-template-columns: 44px 1fr; gap: 1rem; }
}