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

:root{
  --paper:#fafaf8;
  --ink:#1a1a1a;
  --grey:#4a4a4a;
  --line:rgba(26,26,26,.22);
  --hair:rgba(26,26,26,.12);
  --sheet:#fffefb;
  --sans:'Space Grotesk','Archivo',system-ui,-apple-system,'PingFang SC','Hiragino Sans GB','Microsoft YaHei',sans-serif;
  --head:'Archivo','Space Grotesk',system-ui,'PingFang SC','Microsoft YaHei',sans-serif;
}

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

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

body{
  margin:0;
  font-family:var(--sans);
  font-size:1rem;
  line-height:1.75;
  color:var(--ink);
  background-color:var(--paper);
  background-image:
    repeating-linear-gradient(90deg, rgba(26,26,26,.026) 0 1px, transparent 1px 4px),
    repeating-linear-gradient(0deg, rgba(26,26,26,.02) 0 1px, transparent 1px 5px),
    radial-gradient(circle at 12% 6%, rgba(74,74,74,.1), transparent 55%),
    radial-gradient(circle at 86% 64%, rgba(74,74,74,.08), transparent 52%);
  background-attachment:fixed;
}

img{max-width:100%}

a{color:var(--ink)}

a:focus-visible,button:focus-visible{outline:2px dashed var(--ink);outline-offset:3px}

.skip{
  position:absolute;left:-9999px;top:0;
  background:var(--ink);color:var(--paper);
  padding:.7rem 1.1rem;z-index:60;border-radius:0 0 28px 0;text-decoration:none;
}
.skip:focus{left:0}

/* ---------- 头部 ---------- */
.site-head{
  position:relative;
  border-bottom:1px solid var(--line);
  background:rgba(250,250,248,.94);
}

.head-bar{
  max-width:1120px;margin:0 auto;
  display:grid;grid-template-columns:1fr auto 1fr;align-items:center;
  gap:.4rem;padding:.55rem .9rem;
}

.brand{
  display:inline-flex;align-items:center;gap:.5rem;
  text-decoration:none;justify-self:center;
  min-height:44px;padding:.3rem .5rem;
  font-family:var(--head);font-weight:700;letter-spacing:-.02em;font-size:1.15rem;
  transform:rotate(-1.2deg);
}
.mark{
  width:13px;height:13px;display:block;
  background:var(--ink);
  border-radius:2px 8px 2px 8px;
  transform:rotate(8deg);
}

.main-nav ol{
  list-style:none;margin:0;padding:0;
  display:flex;gap:.1rem;
}

.main-nav.nav-left ol{justify-content:flex-end}

.main-nav a{
  display:flex;align-items:center;gap:.35rem;
  min-height:44px;padding:.45rem .55rem;
  font-size:1rem;line-height:1.2;text-decoration:none;color:var(--grey);
  border-radius:28px;border:1px solid transparent;
}
.main-nav a:hover{color:var(--ink);border-color:var(--line);transform:rotate(-.8deg)}

.tick{
  font-family:var(--head);font-size:.72rem;letter-spacing:.06em;
  color:var(--grey);opacity:.7;font-weight:600;
}

/* 粘性锚点条 */
.strip{
  position:sticky;top:0;z-index:40;
  background:var(--paper);
  border-top:1px dashed var(--hair);
  border-bottom:1px solid var(--line);
}
.strip ol{
  list-style:none;margin:0 auto;padding:.3rem .9rem;
  max-width:1120px;display:flex;flex-wrap:wrap;gap:.1rem .5rem;
}
.strip-a{
  display:inline-flex;align-items:center;gap:.35rem;
  min-height:42px;padding:.3rem .55rem;
  font-size:1rem;line-height:1.2;text-decoration:none;color:var(--grey);
  border-bottom:2px solid transparent;
}
.strip-a:hover{color:var(--ink);border-bottom-color:var(--ink)}

/* ---------- 首屏 ---------- */
.hero{
  position:relative;overflow:hidden;
  min-height:70vh;
  display:flex;flex-direction:column;justify-content:center;
  padding:2.4rem 1rem 2.8rem;
  border-bottom:2px solid var(--ink);
}
.hero-bg{
  position:absolute;left:50%;top:52%;
  transform:translate(-50%,-50%) rotate(-3.4deg);
  font-family:var(--head);font-weight:700;
  font-size:clamp(3.6rem,17vw,10rem);line-height:1;
  letter-spacing:-.05em;white-space:nowrap;
  color:rgba(26,26,26,.065);
  pointer-events:none;user-select:none;
}
.hero-in{position:relative;max-width:780px;margin:0 auto;text-align:center}

.hero h1{
  font-family:var(--head);font-weight:700;
  font-size:clamp(1.9rem,6.4vw,3.3rem);
  line-height:1.14;letter-spacing:-.03em;
  margin:0 0 .9rem;text-wrap:balance;
}
.hero .lead{
  max-width:34em;margin:0 auto 1.5rem;
  color:var(--grey);font-size:1.05rem;line-height:1.7;
}
.hero-cta{margin:0}
.cta{
  display:inline-flex;align-items:center;justify-content:center;
  min-height:48px;padding:.65rem 1.7rem;
  font-size:1rem;font-weight:600;text-decoration:none;color:var(--ink);
  border:2px solid var(--ink);border-radius:28px;
  background:var(--sheet);
  transform:rotate(-1.4deg);
}
.cta:hover{background:var(--ink);color:var(--paper);transform:rotate(1deg)}

.hero-fig{
  position:relative;max-width:780px;
  margin:2rem auto 0;padding:.55rem;
  background:#fff;border:1px solid var(--line);
  transform:rotate(-.9deg);
}
.hero-fig::before{
  content:"";position:absolute;top:-11px;left:16%;
  width:82px;height:20px;
  background:rgba(74,74,74,.2);
  transform:rotate(-2.6deg);
}
.hero-img{
  display:block;width:100%;height:auto;
  filter:grayscale(.9) contrast(1.06);
}

/* ---------- 主体 ---------- */
main{padding:0}

.wrap{
  max-width:1120px;margin:0 auto;
  display:grid;grid-template-columns:224px minmax(0,1fr);
  gap:1.8rem;align-items:start;
  padding:2.4rem .9rem 3.6rem;
}

.side{
  position:sticky;top:4.2rem;
  border:2px dashed var(--line);border-radius:28px;
  background:rgba(255,254,251,.75);
  padding:1rem .9rem 1.1rem;
  transform:rotate(.5deg);
}
.side h2{
  font-family:var(--head);font-size:1rem;font-weight:600;
  margin:0;letter-spacing:.28em;color:var(--ink);
}
.side hr{border:0;border-top:2px solid var(--ink);width:28px;margin:.5rem 0 .75rem}
.side-list{list-style:none;margin:0;padding:0}
.side-list a{
  display:flex;align-items:center;gap:.45rem;
  min-height:40px;padding:.3rem .2rem;
  font-size:1rem;line-height:1.3;text-decoration:none;color:var(--grey);
  border-bottom:1px solid transparent;
}
.side-list a:hover{color:var(--ink);border-bottom-color:var(--ink)}

.paper{
  background:var(--sheet);
  border:1px solid var(--line);
  border-radius:28px;
  padding:clamp(1.1rem,3.2vw,2.4rem);
  min-width:0;
}

/* ---------- 正文排版 ---------- */
.doc{display:block;font-size:1.02rem}

.doc > section{
  scroll-margin-top:8rem;
  padding-bottom:1.8rem;margin-bottom:1.8rem;
  border-bottom:1px dashed var(--line);
}
.doc > section:last-child{border-bottom:0;margin-bottom:0;padding-bottom:.4rem}

.doc h2{
  font-family:var(--head);font-weight:700;
  font-size:clamp(1.35rem,3.6vw,1.9rem);
  line-height:1.25;letter-spacing:-.02em;
  margin:0 0 .1rem;
}
.doc h2 + hr{
  border:0;border-top:3px solid var(--ink);
  width:62px;margin:.55rem 0 1.2rem;
}
.doc hr{border:0;border-top:1px dashed var(--line);margin:1.5rem 0}

.doc h3{
  font-family:var(--head);font-weight:600;
  font-size:1.15rem;line-height:1.35;
  margin:1.8rem 0 .5rem;
}
.doc h3 + hr{border:0;border-top:2px solid var(--grey);width:34px;margin:.45rem 0 1rem}

.doc p{margin:0 0 1rem;max-width:44em}
.doc ul,.doc ol{margin:0 0 1.1rem;padding-left:1.4rem}
.doc li{margin:.25rem 0}
.doc strong{font-weight:600}
.doc a{
  text-decoration:underline;
  text-decoration-thickness:2px;text-underline-offset:3px;
}
.doc a:hover{background:rgba(26,26,26,.07)}

.doc blockquote{
  margin:0 0 1.2rem;padding:.2rem 0 .2rem 1rem;
  border-left:3px dashed var(--grey);color:var(--grey);
}

.doc img{
  display:block;height:auto;margin:1rem 0;
  border:1px solid var(--line);
  filter:grayscale(.85) contrast(1.04);
}
.doc figure{margin:1.2rem 0}
.doc figcaption{font-size:1rem;color:var(--grey);margin-top:.4rem}

.doc table{width:100%;border-collapse:collapse;margin:0 0 1.2rem}
.doc th,.doc td{border:1px solid var(--line);padding:.5rem .6rem;text-align:left}
.doc th{font-weight:600}

/* ---------- 页脚 ---------- */
.site-foot{
  border-top:2px solid var(--ink);
  background:#f3f3ef;
  padding:1.8rem .9rem 2.2rem;
  overflow:hidden;
}
.foot-giant{
  font-family:var(--head);font-weight:700;
  font-size:clamp(2.3rem,12.5vw,7.5rem);
  line-height:.95;letter-spacing:-.05em;
  text-align:center;color:rgba(26,26,26,.16);
  transform:rotate(-1deg);
  margin:0 0 1.2rem;
}
.foot-row{
  max-width:1120px;margin:0 auto;
  display:grid;grid-template-columns:1fr auto 1fr;
  align-items:center;gap:.8rem;
  border-top:1px dashed var(--line);padding-top:1rem;
}
.foot-mark{
  justify-self:start;font-family:var(--head);font-weight:600;
  text-decoration:none;font-size:1rem;padding:.5rem .2rem;min-height:40px;
  display:inline-flex;align-items:center;
}
.copy{justify-self:center;margin:0;color:var(--grey);font-size:1rem}
.foot-nav{justify-self:end;max-width:640px}
.foot-nav ol{
  list-style:none;margin:0;padding:0;
  display:flex;flex-wrap:wrap;justify-content:flex-end;gap:.1rem .35rem;
}
.foot-nav a{
  display:inline-flex;align-items:center;
  min-height:40px;padding:.3rem .4rem;
  font-size:1rem;text-decoration:none;color:var(--grey);
  border-bottom:1px solid transparent;
}
.foot-nav a:hover{color:var(--ink);border-bottom-color:var(--ink)}

/* ---------- 显现 ---------- */
html.js .rv,
html.js .doc > section{
  opacity:0;
  transform:translateY(15px) rotate(.25deg);
}
html.js .rv.on,
html.js .doc > section.on{
  opacity:1;transform:none;
  transition:opacity .42s steps(5,end), transform .42s steps(5,end);
  transition-delay:calc(var(--i,0) * 55ms);
}

/* ---------- 响应式 ---------- */
@media (max-width:960px){
  .head-bar{grid-template-columns:1fr 1fr;gap:0;padding:.5rem .8rem}
  .brand{grid-column:1 / -1;grid-row:1;justify-self:center}
  .main-nav.nav-left{grid-column:1;grid-row:2}
  .main-nav.nav-right{grid-column:2;grid-row:2}
  .main-nav ol{flex-direction:column;gap:0}
  .main-nav a{
    border-radius:0;border:0;border-bottom:1px dashed var(--hair);
    justify-content:flex-start;padding:.35rem .2rem;
  }
  .main-nav.nav-right a{justify-content:flex-end}
  .main-nav.nav-left ol{justify-content:flex-start}
  .main-nav a:hover{transform:none}

  .wrap{grid-template-columns:1fr;gap:1.2rem;padding:1.4rem .8rem 3rem}
  .side{position:static;transform:none;border-radius:20px;padding:.9rem .8rem 1rem}
  .side-list{display:grid;grid-template-columns:1fr 1fr;gap:0 .8rem}
  .side-list a{font-size:1rem}
  .doc > section{scroll-margin-top:12rem}
  .paper{border-radius:20px}

  .foot-row{grid-template-columns:1fr;justify-items:center;gap:.5rem;text-align:center}
  .foot-mark,.copy,.foot-nav{justify-self:center}
  .foot-nav ol{justify-content:center}
}

@media (max-width:420px){
  .strip ol{gap:0 .2rem}
  .strip-a{padding:.3rem .4rem}
  .hero{padding:1.8rem .8rem 2.2rem;min-height:auto}
  .wrap{padding:1.2rem .7rem 2.4rem}
  .side-list{grid-template-columns:1fr}
}

@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto}
  html.js .rv,
  html.js .doc > section{opacity:1;transform:none;transition:none}
  .hero-bg{transform:translate(-50%,-50%)}
}

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