@import url('https://fonts.googleapis.com/css2?family=Calistoga:ital@0;1&family=Inter:wght@300;400;500;600;700&family=JetBrains+Mono:wght@400;500&display=swap');

:root {
  --ink: #000000;
  --paper: #ffffff;
  --tint: #f1f1f1;
  --soft: #d9d9d9;
  --r: 4px;
  --pad: clamp(16px, 4vw, 56px);
  --head: 118px;
}

*, *::before, *::after { box-sizing: border-box; }

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

body {
  margin: 0 auto;
  max-width: 1680px;
  background: var(--paper);
  color: var(--ink);
  font-family: Inter, Helvetica, Arial, system-ui, sans-serif;
  font-size: 17px;
  line-height: 1.68;
  font-weight: 400;
  letter-spacing: .01em;
}

img { max-width: 100%; }

a { color: var(--ink); }

:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 2px;
}

/* ---------- 头部：两行 ---------- */
.site-head {
  position: sticky;
  top: 0;
  z-index: 60;
  background: var(--paper);
  border-bottom: 1px solid var(--ink);
}

.bar-top {
  display: flex;
  align-items: center;
  min-height: 58px;
  padding: 6px var(--pad);
  border-bottom: 1px solid var(--ink);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-height: 44px;
  padding: 6px 0;
  text-decoration: none;
  color: var(--ink);
  font-family: Calistoga, Georgia, "Songti SC", serif;
  font-size: 20px;
  line-height: 1.1;
}

.mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  border-radius: 2px;
  background: var(--ink);
  color: var(--paper);
  font-family: "JetBrains Mono", monospace;
  font-size: 16px;
  flex: none;
}

.bar-menu {
  padding: 4px var(--pad) 8px;
}

.menu-wrap {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 4px 8px;
}

.menu {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 2px 2px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.menu > li { position: relative; }

.menu a,
.sub-btn {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 10px 12px;
  border: 1px solid transparent;
  border-radius: var(--r);
  background: none;
  color: var(--ink);
  font-family: inherit;
  font-size: 16px;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
}

.menu a:hover,
.sub-btn:hover,
li.open > .sub-btn {
  background: var(--ink);
  color: var(--paper);
}

.sub-btn::after {
  content: "＋";
  margin-left: 6px;
  font-size: 16px;
  line-height: 1;
}

.sub {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  z-index: 70;
  min-width: 176px;
  margin: 4px 0 0;
  padding: 6px;
  list-style: none;
  background: var(--paper);
  border: 1px solid var(--ink);
  border-radius: var(--r);
  box-shadow: 6px 6px 0 var(--ink);
}

li.open > .sub,
li:hover > .sub { display: block; }

.sub a {
  display: flex;
  min-height: 44px;
  padding: 10px 12px;
}

.cta {
  margin-left: auto;
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 10px 22px;
  border-radius: var(--r);
  background: var(--ink);
  color: var(--paper);
  font-size: 16px;
  font-weight: 600;
  text-decoration: none;
}

.cta:hover { background: var(--paper); color: var(--ink); box-shadow: inset 0 0 0 2px var(--ink); }

/* ---------- 首屏 ---------- */
.hero {
  position: relative;
  display: grid;
  grid-template-rows: auto auto 1fr;
  gap: 20px;
  min-height: 100vh;
  padding: 42px var(--pad) 0;
  border-bottom: 1px solid var(--ink);
  overflow: hidden;
}

.badge {
  justify-self: end;
  margin: 0;
  padding: 8px 12px;
  border: 1px solid var(--ink);
  border-radius: var(--r);
  background: var(--paper);
  font-family: "JetBrains Mono", monospace;
  font-size: 16px;
  line-height: 1.2;
  letter-spacing: .02em;
}

.hero-head { display: grid; grid-template-columns: repeat(12, 1fr); gap: 16px; }

.hero-head h1 {
  grid-column: 1 / span 10;
  margin: 0;
  font-family: Calistoga, Georgia, "Songti SC", serif;
  font-weight: 400;
  font-size: clamp(36px, 6.4vw, 88px);
  line-height: 1.02;
  letter-spacing: -.02em;
  word-break: break-word;
}

.hero-fig {
  align-self: end;
  margin: 0;
  min-height: 220px;
  overflow: hidden;
  border-radius: var(--r) var(--r) 0 0;
  background: var(--tint);
}

.hero-fig img {
  display: block;
  width: 100%;
  height: 100%;
  min-height: 260px;
  object-fit: cover;
  transform: scale(1.12);
  transform-origin: 50% 30%;
  will-change: transform;
}

/* ---------- 正文 + 侧栏 ---------- */
.body-block {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 24px 16px;
  padding: 64px var(--pad) 72px;
  border-bottom: 1px solid var(--ink);
}

.prose {
  grid-column: 1 / span 8;
  min-width: 0;
}

.prose h2 {
  margin: 52px 0 8px;
  font-family: Calistoga, Georgia, "Songti SC", serif;
  font-weight: 400;
  font-size: clamp(26px, 3.2vw, 40px);
  line-height: 1.14;
  letter-spacing: -.01em;
}

.prose h3 {
  margin: 34px 0 8px;
  font-size: 20px;
  font-weight: 700;
  line-height: 1.35;
}

.prose h2:first-child,
.prose h3:first-child { margin-top: 0; }

.prose hr {
  margin: 0 0 18px;
  border: 0;
  border-top: 1px solid var(--ink);
}

.prose p { margin: 0 0 18px; }

.prose ul,
.prose ol { margin: 0 0 18px; padding-left: 1.3em; }

.prose li { margin: 0 0 8px; }

.prose a { text-underline-offset: 3px; }

.prose blockquote {
  margin: 0 0 18px;
  padding: 14px 18px;
  border-left: 4px solid var(--ink);
  background: var(--tint);
  border-radius: 0 var(--r) var(--r) 0;
}

.prose figure {
  margin: 0 0 18px;
  padding: 12px;
  background: var(--tint);
  border-radius: var(--r);
}

.prose img { border-radius: var(--r); display: block; height: auto; }

.prose figure figcaption {
  margin-top: 8px;
  font-size: 16px;
}

.prose table { width: 100%; border-collapse: collapse; margin: 0 0 18px; }

.prose th,
.prose td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--soft);
  text-align: left;
  font-size: 16px;
}

.prose code {
  font-family: "JetBrains Mono", monospace;
  font-size: 16px;
  background: var(--tint);
  padding: 2px 6px;
  border-radius: 2px;
}

section[id] { scroll-margin-top: calc(var(--head) + 12px); }

.rail {
  grid-column: 10 / span 3;
  align-self: start;
  position: sticky;
  top: calc(var(--head) + 16px);
}

.rail h2 {
  margin: 0 0 8px;
  font-size: 16px;
  font-weight: 700;
  letter-spacing: .1em;
}

.rail hr {
  margin: 0 0 10px;
  border: 0;
  border-top: 4px solid var(--ink);
}

.rail-list {
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: rail;
}

.rail-list li {
  counter-increment: rail;
  border-bottom: 1px solid var(--soft);
}

.rail-list a {
  display: flex;
  align-items: center;
  gap: 10px;
  min-height: 44px;
  padding: 10px 2px;
  font-size: 16px;
  line-height: 1.35;
  text-decoration: none;
}

.rail-list a::before {
  content: counter(rail, decimal-leading-zero);
  flex: none;
  font-family: "JetBrains Mono", monospace;
  font-size: 12px;
  letter-spacing: .04em;
}

.rail-list a:hover { text-decoration: underline; text-underline-offset: 4px; }

/* ---------- 页脚 ---------- */
.site-foot {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 32px 16px;
  padding: 56px var(--pad) 24px;
}

.foot-brand { grid-column: 1 / span 7; }

.giant {
  margin: 0;
  font-family: Calistoga, Georgia, "Songti SC", serif;
  font-size: clamp(38px, 8.6vw, 116px);
  line-height: .92;
  letter-spacing: -.03em;
  word-break: break-word;
}

.foot-nav { grid-column: 9 / span 4; }

.foot-nav dl { margin: 0; }

.foot-nav dt {
  margin: 16px 0 2px;
  padding-top: 12px;
  border-top: 1px solid var(--ink);
  font-size: 16px;
  font-weight: 700;
  letter-spacing: .08em;
}

.foot-nav dt:first-of-type { margin-top: 0; padding-top: 0; border-top: 0; }

.foot-nav dd { margin: 0; }

.foot-nav dd a,
.foot-pair a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 8px 0;
  font-size: 16px;
  text-decoration: none;
}

.foot-nav dd a:hover,
.foot-pair a:hover { text-decoration: underline; text-underline-offset: 4px; }

.foot-more {
  grid-column: 1 / span 7;
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px 24px;
}

.foot-kw {
  margin: 0;
  font-size: 16px;
  letter-spacing: .04em;
}

.foot-pair { display: flex; flex-wrap: wrap; gap: 24px; margin: 0; }

.copy {
  grid-column: 1 / span 12;
  margin: 8px 0 0;
  padding-top: 16px;
  border-top: 1px solid var(--ink);
  font-size: 16px;
}

/* ---------- 动效 ---------- */
.js .reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity .62s cubic-bezier(.2, .7, .3, 1), transform .62s cubic-bezier(.2, .7, .3, 1);
}

.js .reveal.in { opacity: 1; transform: none; }

.rail-list li:nth-child(2) { transition-delay: .05s; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .js .reveal { opacity: 1; transform: none; transition: none; }
  .hero-fig img { transform: none !important; }
}

/* ---------- 移动端 ---------- */
@media (max-width: 900px) {
  .prose { grid-column: 1 / span 12; }
  .rail { grid-column: 1 / span 12; position: static; margin-top: 8px; }
  .foot-brand { grid-column: 1 / span 12; }
  .foot-nav { grid-column: 1 / span 6; }
  .foot-more { grid-column: 1 / span 12; }
}

@media (max-width: 760px) {
  :root { --head: 150px; }
  body { font-size: 17px; }
  .hero {
    min-height: 0;
    padding: 24px var(--pad) 0;
    grid-template-rows: auto auto auto;
    gap: 14px;
  }
  .badge { justify-self: start; }
  .hero-head h1 { grid-column: 1 / span 12; }
  .hero-fig { min-height: 180px; }
  .hero-fig img { min-height: 190px; }
  .body-block { padding: 40px var(--pad) 48px; gap: 20px; }
  .site-foot { padding: 40px var(--pad) 20px; gap: 24px; }
  .foot-nav { grid-column: 1 / span 12; }
  .cta { margin-left: 0; width: 100%; justify-content: center; }
  .menu-wrap { gap: 6px; }
  .menu { gap: 2px; }
  .sub { position: static; margin: 4px 0 6px; box-shadow: none; min-width: 0; }
  .sub a { min-height: 44px; }
}

@media (max-width: 420px) {
  .bar-top { min-height: 52px; }
  .menu a, .sub-btn { padding: 10px 9px; }
}

button[aria-expanded]{min-width:44px;min-height:44px}