@import url('https://fonts.googleapis.com/css2?family=Fira+Code:wght@400;500;600;700&family=Fira+Sans:wght@300;400;500;600;700&display=swap');

:root {
  --ink: #000000;
  --paper: #ffffff;
  --pad: 5vw;
  --mono: "Fira Code", ui-monospace, SFMono-Regular, Menlo, monospace;
  --sans: "Fira Sans", "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
}

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

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

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.65;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

a { color: inherit; }

img { max-width: 100%; }

/* ---------- 顶栏 ---------- */
.top {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 1rem;
  padding: 0.4rem var(--pad);
  border-bottom: 2px solid var(--ink);
  background: var(--paper);
}

.top-nav ol {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.1rem 1.1rem;
  margin: 0;
  padding: 0;
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.01em;
}

.top-nav--l ol { justify-content: flex-start; }
.top-nav--r ol { justify-content: flex-end; }

.top-nav a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 0.1rem;
  text-decoration: none;
  border-bottom: 2px solid transparent;
}

.top-nav a:hover,
.top-nav a:focus-visible { border-bottom-color: var(--ink); }

.brand-cell {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.05rem;
  padding: 0.2rem 0.5rem;
}

.brand {
  font-size: 1.02rem;
  font-weight: 900;
  letter-spacing: -0.03em;
  text-decoration: none;
  white-space: nowrap;
}

.reach {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  font-family: var(--mono);
  font-size: 0.7rem;
  letter-spacing: 0.18em;
  text-decoration: none;
  opacity: 0.55;
}

.reach:hover { opacity: 1; }

/* ---------- 粘性锚点条 ---------- */
.rail {
  position: sticky;
  top: 0;
  z-index: 20;
  background: var(--ink);
  color: var(--paper);
  border-bottom: 2px solid var(--ink);
}

.rail-nav {
  overflow-x: auto;
  padding: 0 var(--pad);
  scrollbar-width: thin;
}

.rail-nav ol {
  list-style: none;
  display: flex;
  gap: 1.5rem;
  margin: 0;
  padding: 0;
  white-space: nowrap;
  font-family: var(--mono);
  font-size: 0.76rem;
}

.rail-nav a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  color: var(--paper);
  text-decoration: none;
  opacity: 0.6;
  border-bottom: 2px solid transparent;
}

.rail-nav a:hover,
.rail-nav a:focus-visible,
.rail-nav a.is-on {
  opacity: 1;
  border-bottom-color: var(--paper);
}

/* ---------- 主区 ---------- */
main { padding: 0 var(--pad); }

.hero {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  align-items: center;
  gap: clamp(1.4rem, 4vw, 4rem);
  min-height: 45vh;
  margin: 0 calc(var(--pad) * -1);
  padding: clamp(1.8rem, 4vw, 3.4rem) var(--pad);
  background: var(--ink);
  color: var(--paper);
}

.hero-art {
  position: relative;
  margin: 0;
  min-height: 180px;
  background: #101010;
  border: 2px solid var(--paper);
  border-radius: 4px;
  overflow: hidden;
}

.hero-img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.hero-art figcaption {
  position: absolute;
  left: 0;
  bottom: 0;
  padding: 0.35rem 0.65rem;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.02em;
}

.hero-copy { text-align: right; }

h1 {
  margin: 0;
  font-size: clamp(2.1rem, 8vw, 6.2rem);
  font-weight: 900;
  letter-spacing: -0.05em;
  line-height: 0.98;
}

.lede {
  margin: 1.1rem 0 0 auto;
  max-width: 34ch;
  font-size: clamp(0.95rem, 1.5vw, 1.1rem);
  line-height: 1.6;
  color: #d6d6d6;
}

.stage {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 258px;
  align-items: start;
  gap: clamp(1.6rem, 4vw, 3.6rem);
  padding: clamp(2rem, 5vw, 4rem) 0;
}

/* ---------- 正文 ---------- */
.body > div {
  padding: clamp(2.2rem, 5vw, 4.6rem) 0;
  border-top: 2px solid var(--ink);
  scroll-margin-top: 76px;
}

.body > div:first-child {
  border-top: 0;
  padding-top: 0;
}

.body h2 {
  margin: 0.1rem 0 1.1rem;
  font-size: clamp(1.7rem, 4.4vw, 3.4rem);
  font-weight: 900;
  letter-spacing: -0.04em;
  line-height: 1.02;
}

.body h3 {
  margin: 2rem 0 0.6rem;
  font-size: clamp(1.15rem, 2.2vw, 1.6rem);
  font-weight: 700;
  letter-spacing: -0.02em;
}

.body p {
  margin: 0 0 1rem;
  max-width: 64ch;
}

.body ul,
.body ol {
  max-width: 64ch;
  padding-left: 1.2rem;
}

.body li { margin-bottom: 0.4rem; }

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

.body img {
  border-radius: 4px;
}

.body code {
  font-family: var(--mono);
  font-size: 0.9em;
}

small {
  display: block;
  margin-bottom: 0.5rem;
  font-family: var(--mono);
  font-size: 0.7rem;
  letter-spacing: 0.24em;
  font-weight: 500;
  opacity: 0.55;
}

/* ---------- 右侧栏 ---------- */
.side {
  position: sticky;
  top: 62px;
  padding: 1rem 1rem 1.2rem;
  border: 2px solid var(--ink);
  border-radius: 4px;
  background: rgba(255, 255, 255, 0.72);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
}

.side h2 {
  margin: 0 0 0.7rem;
  font-size: 1.25rem;
  font-weight: 900;
  letter-spacing: -0.03em;
}

.side ol {
  list-style: none;
  margin: 0;
  padding: 0;
  font-family: var(--mono);
  font-size: 0.78rem;
}

.side li + li { border-top: 1px solid rgba(0, 0, 0, 0.14); }

.side a {
  display: flex;
  align-items: center;
  min-height: 40px;
  text-decoration: none;
}

.side a:hover { text-decoration: underline; }

.side code {
  display: block;
  margin-top: 1rem;
  font-family: var(--mono);
  font-size: 0.72rem;
  opacity: 0.55;
  word-break: break-all;
}

/* ---------- 页脚 ---------- */
footer {
  display: grid;
  grid-template-columns: 1.15fr 1fr;
  gap: clamp(1.4rem, 4vw, 3.6rem);
  margin-top: clamp(2rem, 6vw, 4.5rem);
  padding: clamp(2rem, 4.5vw, 3.2rem) var(--pad) 1.6rem;
  background: var(--ink);
  color: var(--paper);
  border-top: 2px solid var(--ink);
}

.f-brand {
  margin: 0 0 0.5rem;
  font-size: 1.35rem;
  font-weight: 900;
  letter-spacing: -0.03em;
}

footer address {
  font-style: normal;
  font-family: var(--mono);
  font-size: 0.78rem;
  opacity: 0.65;
  word-break: break-all;
}

.f-links {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  align-content: flex-start;
  gap: 0.1rem 1.1rem;
  margin: 0;
  padding: 0;
  font-family: var(--mono);
  font-size: 0.8rem;
}

.f-links a {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  color: var(--paper);
  text-decoration: none;
}

.f-links a:hover { text-decoration: underline; }

.f-bottom {
  grid-column: 1 / -1;
  margin: 0;
  padding-top: 0.9rem;
  border-top: 1px solid rgba(255, 255, 255, 0.28);
  font-family: var(--mono);
  font-size: 0.74rem;
  opacity: 0.6;
}

/* ---------- 回到顶部 ---------- */
.totop {
  position: fixed;
  right: 0.9rem;
  bottom: 0.9rem;
  z-index: 30;
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0.6rem 0.9rem;
  background: var(--paper);
  color: var(--ink);
  border: 2px solid var(--ink);
  border-radius: 4px;
  font-family: var(--mono);
  font-size: 0.76rem;
  text-decoration: none;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s ease;
}

.totop.is-shown {
  opacity: 1;
  pointer-events: auto;
}

/* ---------- 动效 ---------- */
html.js .reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

html.js .reveal.on {
  opacity: 1;
  transform: none;
}

/* ---------- 移动端 ---------- */
@media (max-width: 780px) {
  :root { --pad: 1.1rem; }

  .top {
    grid-template-columns: 1fr;
    gap: 0.1rem;
    padding: 0.3rem var(--pad) 0.5rem;
  }

  .brand-cell {
    order: -1;
    padding: 0.35rem 0 0.1rem;
  }

  .top-nav ol {
    justify-content: center;
    gap: 0.1rem 0.9rem;
  }

  .top-nav a { min-height: 40px; }

  .hero {
    grid-template-columns: 1fr;
    gap: 1.2rem;
    padding: 1.5rem var(--pad) 2rem;
  }

  .hero-art { min-height: 150px; }

  .hero-copy { text-align: left; }

  .lede { margin-left: 0; }

  .stage { grid-template-columns: 1fr; gap: 1.6rem; }

  .side {
    position: static;
    order: 2;
  }

  .body > div { scroll-margin-top: 66px; }

  footer { grid-template-columns: 1fr; }
}

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

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