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

:root{
  --blue:#3bb1ff;
  --red:#ff5252;
  --ink:#000000;
  --paper:#fffdf5;
  --tint:#e8f6ff;
  --tint2:#ffe9e9;
  --head:"Space Grotesk","DM Sans",system-ui,-apple-system,sans-serif;
  --body:"DM Sans",system-ui,-apple-system,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
}

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

html{
  scroll-behavior:smooth;
  scroll-padding-bottom:120px;
  -webkit-text-size-adjust:100%;
}

body{
  margin:0;
  padding:0 0 100px;
  background:var(--paper);
  color:var(--ink);
  font-family:var(--body);
  font-size:17px;
  line-height:1.72;
  overflow-x:hidden;
}

h1,h2,h3,h4{
  font-family:var(--head);
  font-weight:700;
  line-height:1.2;
  letter-spacing:-.02em;
  margin:0;
}

p{ margin:0 0 1.05em; }
p:last-child{ margin-bottom:0; }

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

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

:focus-visible{
  outline:3px solid var(--red);
  outline-offset:2px;
}

/* 首屏 */
.hero{
  position:relative;
  min-height:100vh;
  display:grid;
  place-items:center;
  padding:110px 20px 190px;
  background:var(--ink);
  color:#fff;
  text-align:center;
  overflow:hidden;
}

.hero__title{
  position:relative;
  z-index:2;
  margin:0;
  max-width:16ch;
  font-size:clamp(38px,8.4vw,108px);
  font-weight:700;
  text-shadow:7px 7px 0 var(--red);
}

.hero__bar{
  position:absolute;
  z-index:1;
  display:block;
  width:min(38vw,300px);
  height:62px;
  border:3px solid #fff;
  will-change:transform;
}

.hero__bar--1{ top:13%; left:-6%; background:var(--blue); transform:rotate(-14deg); }
.hero__bar--2{ top:29%; right:-8%; background:var(--red); transform:rotate(11deg); }
.hero__bar--3{ bottom:27%; left:-9%; background:#ffffff; transform:rotate(6deg); }
.hero__bar--4{ bottom:15%; right:-4%; background:var(--blue); transform:rotate(-8deg); }

.hero__cut{
  position:absolute;
  z-index:1;
  left:-4%;
  right:-4%;
  bottom:-2px;
  height:92px;
  background:var(--blue);
  border-top:3px solid var(--ink);
  clip-path:polygon(0 46%,100% 0,100% 100%,0 100%);
}

.hero__cut2{
  position:absolute;
  z-index:1;
  left:-4%;
  right:-4%;
  bottom:-2px;
  height:48px;
  background:var(--red);
  clip-path:polygon(0 100%,100% 34%,100% 100%,0 100%);
}

/* 版面 */
.wrap{
  display:grid;
  grid-template-columns:minmax(0,1fr) 264px;
  gap:40px;
  max-width:1180px;
  margin:0 auto;
  padding:0 24px;
}

.doc{
  counter-reset:sec;
  min-width:0;
  overflow:hidden;
  background:#fff;
  border:3px solid var(--ink);
  border-radius:4px;
  box-shadow:8px 8px 0 var(--ink);
}

.doc > article{
  position:relative;
  padding:44px 26px 44px 44px;
  border-top:3px solid var(--ink);
  scroll-margin-top:20px;
  scroll-margin-bottom:130px;
}

.doc > article:first-child{ border-top:0; }
.doc > article:nth-child(4n+1){ background:#ffffff; }
.doc > article:nth-child(4n+2){ background:var(--tint); }
.doc > article:nth-child(4n+3){ background:#ffffff; }
.doc > article:nth-child(4n+4){ background:var(--tint2); }

.doc > article::before{
  counter-increment:sec;
  content:"0" counter(sec);
  position:absolute;
  left:11px;
  top:36px;
  font-family:var(--head);
  font-size:15px;
  font-weight:700;
  line-height:1;
  letter-spacing:.02em;
  color:var(--ink);
  background:var(--blue);
  border:2px solid var(--ink);
  border-radius:3px;
  padding:4px 5px;
}

/* 正文元素 */
.doc h2{
  display:inline-block;
  font-size:clamp(24px,3.6vw,36px);
  margin:0 0 16px;
  padding-bottom:5px;
  border-bottom:4px solid var(--red);
}

.doc h3{
  font-size:clamp(20px,2.4vw,24px);
  margin:26px 0 10px;
}

.doc h4{
  font-size:18px;
  margin:20px 0 8px;
}

.doc p,
.doc li{
  max-width:64ch;
  font-size:17px;
}

.doc ul,
.doc ol{
  margin:0 0 1.1em;
  padding-left:1.35em;
}

.doc li{ margin-bottom:.4em; }

.doc a{
  text-decoration:underline;
  text-decoration-thickness:2px;
  text-underline-offset:3px;
  text-decoration-color:var(--red);
}

.doc a:hover{ background:var(--blue); }

.doc blockquote{
  margin:0 0 1.1em;
  padding:14px 18px;
  background:#fff;
  border:3px solid var(--ink);
  border-radius:4px;
  box-shadow:5px 5px 0 var(--ink);
}

.doc blockquote p:last-child{ margin-bottom:0; }

.doc figure{
  margin:0 0 1.2em;
  border:3px solid var(--ink);
  border-radius:4px;
  background:#fff;
  box-shadow:5px 5px 0 var(--ink);
  overflow:hidden;
}

.doc figure img{ width:100%; }

.doc figcaption{
  padding:8px 12px;
  font-size:16px;
  border-top:3px solid var(--ink);
}

.doc code{
  font-family:ui-monospace,SFMono-Regular,Menlo,monospace;
  font-size:16px;
  background:var(--tint2);
  border:2px solid var(--ink);
  border-radius:3px;
  padding:1px 4px;
}

.doc hr{
  height:0;
  margin:26px 0;
  border:0;
  border-top:3px solid var(--ink);
}

.doc table{
  width:100%;
  border-collapse:collapse;
  margin:0 0 1.2em;
  font-size:16px;
}

.doc th,
.doc td{
  border:2px solid var(--ink);
  padding:8px 10px;
  text-align:left;
}

.doc th{ background:var(--tint); }

/* 侧栏 */
.side{
  align-self:start;
  position:sticky;
  top:22px;
  max-height:calc(100vh - 150px);
  overflow:auto;
  padding:16px 16px 20px;
  background:#fff;
  border:3px solid var(--ink);
  border-radius:4px;
  box-shadow:6px 6px 0 var(--ink);
}

.side__cue{
  display:inline-block;
  font-family:var(--head);
  font-size:14px;
  font-weight:700;
  letter-spacing:.14em;
  background:var(--red);
  border:2px solid var(--ink);
  border-radius:3px;
  padding:2px 7px;
}

.side h2{
  font-size:22px;
  margin:8px 0 12px;
}

.side__list menu{
  list-style:none;
  margin:0;
  padding:0;
  display:grid;
  gap:6px;
}

.side__list a{
  display:flex;
  align-items:center;
  min-height:40px;
  padding:6px 10px;
  font-weight:500;
  text-decoration:none;
  background:var(--paper);
  border:2px solid var(--ink);
  border-radius:3px;
  transition:transform .12s ease,box-shadow .12s ease,background .12s ease;
}

/* 页脚 */
.foot{
  display:grid;
  grid-template-columns:1fr 1fr;
  gap:6px 20px;
  align-items:start;
  max-width:1180px;
  margin:46px auto 0;
  padding:22px 24px 6px;
  border-top:3px solid var(--ink);
}

.foot__brand{
  margin:0;
  font-family:var(--head);
  font-size:20px;
  font-weight:700;
}

.foot__links{
  margin:0;
  display:flex;
  flex-wrap:wrap;
  justify-content:flex-end;
  gap:2px 12px;
  font-size:16px;
}

.foot__links a{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  padding:0 2px;
  text-decoration:none;
  border-bottom:2px solid var(--red);
}

.foot small{
  grid-column:1 / -1;
  display:block;
  padding:12px 0 6px;
  text-align:center;
  font-size:16px;
}

/* 底部导航 */
.dock{
  position:fixed;
  left:0;
  right:0;
  bottom:0;
  z-index:60;
  display:grid;
  grid-template-columns:1fr auto 1fr;
  align-items:center;
  gap:10px;
  padding:10px 18px;
  background:#fff;
  border-top:3px solid var(--ink);
}

.dock__side{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:8px;
  min-width:0;
}

.dock__side--l{ justify-content:flex-end; }
.dock__side--r{ justify-content:flex-start; }

.brand,
.cta{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  font-family:var(--head);
  font-weight:700;
  text-decoration:none;
  border:3px solid var(--ink);
  border-radius:4px;
  box-shadow:4px 4px 0 var(--ink);
  transition:transform .12s ease,box-shadow .12s ease;
  white-space:nowrap;
}

.brand{
  font-size:23px;
  padding:6px 16px;
  background:var(--blue);
}

.cta{
  font-size:16px;
  padding:6px 16px;
  background:var(--red);
}

.grp{ position:relative; }

.grp > summary{
  display:flex;
  align-items:center;
  min-height:44px;
  padding:0 12px;
  font-size:16px;
  font-weight:700;
  cursor:pointer;
  list-style:none;
  background:#fff;
  border:3px solid var(--ink);
  border-radius:4px;
  transition:transform .12s ease,box-shadow .12s ease,background .12s ease;
}

.grp > summary::-webkit-details-marker{ display:none; }

.grp > summary::after{
  content:"";
  width:0;
  height:0;
  margin-left:8px;
  border-left:5px solid transparent;
  border-right:5px solid transparent;
  border-top:6px solid var(--ink);
  transition:transform .12s ease;
}

.grp[open] > summary{
  background:var(--blue);
  box-shadow:4px 4px 0 var(--ink);
}

.grp[open] > summary::after{ transform:rotate(180deg); }

.grp:not([open]) > menu{ display:none; }

.grp > menu{
  position:absolute;
  left:0;
  bottom:calc(100% + 14px);
  z-index:70;
  min-width:200px;
  margin:0;
  padding:8px;
  list-style:none;
  background:#fff;
  border:3px solid var(--ink);
  border-radius:4px;
  box-shadow:7px 7px 0 var(--ink);
}

.dock__side--r .grp > menu{
  left:auto;
  right:0;
}

.grp > menu li + li{ margin-top:6px; }

.grp > menu a{
  display:flex;
  align-items:center;
  min-height:44px;
  padding:6px 10px;
  font-size:16px;
  font-weight:500;
  text-decoration:none;
  border:2px solid var(--ink);
  border-radius:3px;
}

.grp > menu a:hover{ background:var(--blue); }

/* 悬停微交互 */
@media (hover:hover){
  .brand:hover,
  .cta:hover,
  .grp > summary:hover{
    transform:translate(-2px,-2px);
    box-shadow:6px 6px 0 var(--ink);
  }

  .side__list a:hover{
    background:var(--blue);
    transform:translate(-2px,-2px);
    box-shadow:3px 3px 0 var(--ink);
  }
}

/* 窄屏 */
@media (max-width:960px){
  .wrap{
    grid-template-columns:1fr;
    gap:28px;
    padding:0 18px;
  }

  .side{
    position:static;
    max-height:none;
  }

  .foot{
    grid-template-columns:1fr;
    gap:6px;
    padding:20px 18px 6px;
  }

  .foot__links{ justify-content:flex-start; }
}

@media (max-width:820px){
  body{ padding-bottom:136px; }
  html{ scroll-padding-bottom:160px; }

  .hero{ padding:96px 16px 172px; }

  .dock{
    row-gap:8px;
    padding:8px 10px;
    gap:8px;
  }

  .brand{
    grid-column:2;
    grid-row:1;
    justify-self:center;
    font-size:20px;
  }

  .dock__side--l{
    grid-column:1 / 3;
    grid-row:2;
    justify-content:center;
  }

  .dock__side--r{
    grid-column:3 / 4;
    grid-row:2;
    justify-content:flex-end;
  }

  .grp > summary,
  .cta{
    padding:0 10px;
  }

  .doc > article{
    padding:36px 18px 36px 40px;
    scroll-margin-bottom:180px;
  }

  .doc > article::before{ top:30px; left:9px; }

  .doc p,
  .doc li{ font-size:17px; }
}

@media (max-width:420px){
  .hero__title{ text-shadow:5px 5px 0 var(--red); }
  .brand{ font-size:18px; padding:6px 12px; }
  .cta{ padding:0 10px; }
  .grp > summary{ padding:0 8px; }
}

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

  .brand,
  .cta,
  .grp > summary,
  .side__list a,
  .hero__bar{
    transition:none;
  }
}

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