@import url('https://fonts.googleapis.com/css2?family=Baloo+2:wght@400;500;600;700&family=Comic+Neue:wght@300;400;700&display=swap');

:root {
  --ink: #000000;
  --paper: #ffffff;
  --hair: rgba(0, 0, 0, 0.14);
  --dot: rgba(0, 0, 0, 0.18);
  --radius: 28px;
  --rail: 264px;
  --font: 'Baloo 2', 'Comic Neue', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', system-ui, sans-serif;
}

* {
  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(--font);
  font-size: 17px;
  line-height: 1.7;
  letter-spacing: 0.01em;
}

a {
  color: var(--ink);
  text-decoration: none;
}

a:focus-visible,
button:focus-visible,
input:focus-visible {
  outline: 3px solid var(--ink);
  outline-offset: 3px;
}

img {
  display: block;
  max-width: 100%;
  height: auto;
}

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

/* ---------- 左侧固定栏 ---------- */

.masthead {
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  z-index: 20;
  width: var(--rail);
  padding: 2.2rem 1.5rem 1.6rem;
  display: flex;
  flex-direction: column;
  gap: 1.4rem;
  background: var(--paper);
  border-right: 2px solid var(--ink);
  overflow-y: auto;
}

.brand {
  display: inline-block;
  align-self: flex-start;
  font-size: 1.65rem;
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.02em;
  padding: 0.25rem 0;
  border-bottom: 4px solid var(--ink);
  transition: letter-spacing 0.22s ease;
}

.brand:hover {
  letter-spacing: 0.02em;
}

.masthead nav p {
  display: flex;
  flex-direction: column;
  margin: 0;
}

.masthead nav a {
  display: block;
  padding: 0.72rem 0.2rem;
  font-size: 1rem;
  border-bottom: 1px solid var(--hair);
  transition: padding-left 0.2s ease, background 0.2s ease;
}

.masthead nav a:first-child {
  border-top: 1px solid var(--hair);
}

.masthead nav a:hover {
  padding-left: 0.7rem;
  background: rgba(0, 0, 0, 0.045);
}

.mast-cta {
  margin: auto 0 0;
  padding-top: 1rem;
}

.mast-cta a {
  display: block;
  padding: 0.7rem 1rem;
  text-align: center;
  font-size: 1rem;
  border: 2px solid var(--ink);
  border-radius: 999px;
  background: var(--ink);
  color: var(--paper);
  transition: background 0.22s ease, color 0.22s ease;
}

.mast-cta a:hover {
  background: var(--paper);
  color: var(--ink);
}

/* ---------- 主体网格 ---------- */

main {
  margin-left: var(--rail);
}

.shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 232px;
  grid-template-areas:
    'hero hero'
    'body rail';
  column-gap: clamp(1.6rem, 3.4vw, 3.4rem);
  max-width: 1440px;
  padding: 0 clamp(1.2rem, 3vw, 3rem) 0 clamp(1.2rem, 3vw, 4rem);
}

/* ---------- 首屏 ---------- */

.hero {
  grid-area: hero;
  position: relative;
  min-height: 100vh;
  display: grid;
  grid-template-columns: 1fr 1fr;
  grid-template-areas: 'fig text';
  align-items: center;
  gap: clamp(1.2rem, 4vw, 3.4rem);
  padding: clamp(2rem, 7vh, 5rem) 0;
  background-image: radial-gradient(var(--dot) 1.2px, transparent 1.2px);
  background-size: 15px 15px;
  background-position: 0 0;
}

.hero-text {
  grid-area: text;
  text-align: right;
}

.hero h1 {
  margin: 0 0 1rem;
  font-size: clamp(2rem, 5.4vw, 4.4rem);
  line-height: 1.04;
  letter-spacing: -0.03em;
  font-weight: 700;
}

.hero-desc {
  margin: 0 0 0 auto;
  max-width: 30ch;
  font-size: 1rem;
  line-height: 1.75;
  color: rgba(0, 0, 0, 0.78);
}

.collage {
  grid-area: fig;
  margin: 0;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  align-items: center;
}

.tile {
  aspect-ratio: 3 / 4;
  border: 2px solid var(--ink);
  border-radius: var(--radius);
  overflow: hidden;
  background-image: radial-gradient(var(--dot) 1px, transparent 1px);
  background-size: 11px 11px;
  background-color: var(--paper);
}

.tile img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.tile-a {
  transform: translateY(-2.2rem);
}

.tile-b {
  transform: translateY(2.2rem);
}

/* ---------- 正文 ---------- */

.body {
  grid-area: body;
  min-width: 0;
  padding-bottom: 4rem;
  max-width: 74ch;
}

.body article[id] {
  padding: 3.2rem 0;
  border-top: 2px solid var(--ink);
  scroll-margin-top: 2rem;
}

.body article[id]:last-child {
  padding-bottom: 1rem;
}

.body h2 {
  margin: 0 0 0.5rem;
  font-size: clamp(1.4rem, 2.7vw, 2rem);
  line-height: 1.25;
  letter-spacing: -0.015em;
}

.body h2 + hr {
  width: 64px;
  border-top: 3px solid var(--ink);
  margin: 0.5rem 0 1.5rem;
}

.body h3 {
  margin: 2rem 0 0.5rem;
  font-size: 1.2rem;
  line-height: 1.35;
}

.body p {
  margin: 0.9rem 0;
  line-height: 1.85;
}

.body ul,
.body ol {
  padding-left: 1.3rem;
  margin: 1rem 0;
}

.body li {
  margin: 0.4rem 0;
}

.body a {
  text-decoration: underline;
  text-underline-offset: 4px;
  text-decoration-thickness: 2px;
}

.body strong {
  font-weight: 700;
}

.body figure {
  margin: 1.5rem 0;
}

.body figure img {
  border: 2px solid var(--ink);
  border-radius: var(--radius);
  width: 100%;
}

.body blockquote {
  margin: 1.4rem 0;
  padding: 0.6rem 0 0.6rem 1.2rem;
  border-left: 4px solid var(--ink);
  font-size: 1.05rem;
}

.body blockquote p {
  margin: 0.4rem 0;
}

/* ---------- 右侧栏 ---------- */

.rail {
  grid-area: rail;
  position: sticky;
  top: 2rem;
  align-self: start;
  margin: 3.2rem 0 3rem;
  padding-left: 1.1rem;
  border-left: 2px solid var(--ink);
}

.rail h2 {
  margin: 0;
  font-size: 1.05rem;
  letter-spacing: 0.06em;
}

.rail h2 + hr {
  width: 36px;
  border-top: 2px solid var(--ink);
  margin: 0.6rem 0 0.8rem;
}

.rail p {
  margin: 0;
}

.rail p a {
  display: block;
  padding: 0.62rem 0;
  font-size: 1rem;
  border-bottom: 1px solid var(--hair);
  transition: padding-left 0.18s ease;
  animation: railIn 0.45s ease both;
}

.rail p a:hover {
  padding-left: 0.35rem;
}

.rail p a:nth-child(2) { animation-delay: 40ms; }
.rail p a:nth-child(3) { animation-delay: 80ms; }
.rail p a:nth-child(4) { animation-delay: 120ms; }
.rail p a:nth-child(5) { animation-delay: 160ms; }
.rail p a:nth-child(6) { animation-delay: 200ms; }
.rail p a:nth-child(7) { animation-delay: 240ms; }

@keyframes railIn {
  from {
    opacity: 0;
    transform: translateX(8px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

.rail .rail-top {
  margin-top: 0.9rem;
}

.rail .rail-top a {
  border-bottom: 0;
  font-size: 1rem;
  text-decoration: underline;
  text-underline-offset: 4px;
}

/* ---------- 页脚 ---------- */

.foot {
  margin-left: var(--rail);
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: 1rem 2rem;
  max-width: 1440px;
  padding: 2.4rem clamp(1.2rem, 3vw, 3rem) 1rem clamp(1.2rem, 3vw, 4rem);
  border-top: 2px solid var(--ink);
}

.foot p {
  margin: 0;
}

.foot-brand {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.foot-links {
  display: flex;
  flex-wrap: wrap;
  align-content: flex-start;
  gap: 0 0.9rem;
}

.foot-links a {
  display: inline-block;
  padding: 0.68rem 0;
  min-height: 44px;
  font-size: 1rem;
  border-bottom: 1px solid var(--hair);
}

.foot-links a:hover {
  border-bottom-color: var(--ink);
}

.foot-sub {
  grid-column: 1;
  grid-row: 2;
  padding-top: 0.2rem;
}

.sub {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  max-width: 380px;
}

.sub input {
  flex: 1 1 150px;
  min-height: 46px;
  padding: 0.4rem 1.1rem;
  font: inherit;
  font-size: 1rem;
  color: var(--ink);
  background: var(--paper);
  border: 2px solid var(--ink);
  border-radius: 999px;
}

.sub button {
  min-height: 46px;
  padding: 0.4rem 1.5rem;
  font: inherit;
  font-size: 1rem;
  cursor: pointer;
  color: var(--paper);
  background: var(--ink);
  border: 2px solid var(--ink);
  border-radius: 999px;
  transition: background 0.22s ease, color 0.22s ease;
}

.sub button:hover {
  background: var(--paper);
  color: var(--ink);
}

.foot small {
  grid-column: 1 / -1;
  display: block;
  margin-top: 1.4rem;
  padding-top: 1rem;
  border-top: 1px solid var(--hair);
  text-align: center;
  font-size: 1rem;
}

/* ---------- 滚动出现 ---------- */

article[id].will {
  opacity: 0;
  transform: translateY(22px);
}

article[id].in {
  opacity: 1;
  transform: none;
  transition: opacity 0.5s ease, transform 0.5s ease;
}

/* ---------- 窄屏 ---------- */

@media (max-width: 1000px) {
  .masthead {
    position: static;
    width: auto;
    padding: 1.1rem 1.2rem 0.9rem;
    flex-direction: row;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.5rem 1rem;
    border-right: 0;
    border-bottom: 2px solid var(--ink);
    overflow: visible;
  }

  .brand {
    font-size: 1.35rem;
  }

  .mast-cta {
    margin: 0 0 0 auto;
    padding: 0;
  }

  .mast-cta a {
    padding: 0.55rem 0.95rem;
  }

  .masthead nav {
    flex: 1 1 100%;
  }

  .masthead nav p {
    flex-direction: row;
    flex-wrap: wrap;
    gap: 0 1rem;
  }

  .masthead nav a {
    padding: 0.65rem 0;
    min-height: 44px;
    border-bottom: 0;
  }

  .masthead nav a:first-child {
    border-top: 0;
  }

  main,
  .foot {
    margin-left: 0;
  }

  .shell {
    grid-template-columns: minmax(0, 1fr);
    grid-template-areas:
      'hero'
      'body'
      'rail';
    padding: 0 1.2rem;
  }

  .hero {
    min-height: 0;
    grid-template-columns: minmax(0, 1fr);
    grid-template-areas:
      'text'
      'fig';
    padding: 1.6rem 0 2rem;
  }

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

  .hero-desc {
    margin-left: 0;
    max-width: none;
  }

  .tile-a,
  .tile-b {
    transform: none;
  }

  .body {
    padding-bottom: 2rem;
  }

  .body article[id] {
    padding: 2.2rem 0;
    scroll-margin-top: 1rem;
  }

  .rail {
    position: static;
    margin: 0 0 2.4rem;
    padding: 1.4rem 0 0;
    border-left: 0;
    border-top: 2px solid var(--ink);
  }

  .foot {
    grid-template-columns: minmax(0, 1fr);
    padding: 1.6rem 1.2rem 1rem;
  }

  .foot-sub,
  .foot small {
    grid-column: 1;
    grid-row: auto;
  }

  .foot small {
    margin-top: 1rem;
  }
}

@media (max-width: 420px) {
  .hero h1 {
    font-size: 2rem;
  }

  .collage {
    gap: 0.7rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-delay: 0ms !important;
    transition-duration: 0.001ms !important;
  }

  article[id].will {
    opacity: 1;
    transform: none;
  }
}

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