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

:root{
  --paper:#fafaf8;
  --ink:#1a1a1a;
  --gray:#4a4a4a;
  --line:rgba(26,26,26,.22);
  --line-soft:rgba(26,26,26,.12);
  --card:#ffffff;
  --grain:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.85' numOctaves='3'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='160' height='160' filter='url(%23n)' opacity='.055'/%3E%3C/svg%3E");
}

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

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

body{
  margin:0;
  background-color:var(--paper);
  background-image:var(--grain);
  color:var(--ink);
  font-family:"Plus Jakarta Sans",system-ui,-apple-system,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  font-size:17px;
  line-height:1.75;
  font-weight:400;
  letter-spacing:.005em;
  overflow-x:hidden;
}

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

a{color:var(--ink);text-decoration:none}
a:hover{text-decoration:underline wavy .05em;text-underline-offset:4px}

button,input{font:inherit;color:inherit}

/* ---------- 顶栏 ---------- */
.topbar{
  position:sticky;
  top:0;
  z-index:50;
  display:grid;
  grid-template-columns:1fr auto 1fr;
  align-items:center;
  gap:8px;
  padding:9px 16px;
  background:rgba(250,250,248,.95);
  border-bottom:1.5px solid var(--line);
  backdrop-filter:blur(3px);
}

.brand{
  justify-self:center;
  font-size:clamp(14px,3.7vw,19px);
  font-weight:700;
  letter-spacing:-.01em;
  text-align:center;
  padding:8px 4px;
  line-height:1.3;
  background:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 120 8' preserveAspectRatio='none'%3E%3Cpath d='M2 5 Q 18 1 36 5 T 70 5 T 104 5 T 118 4' fill='none' stroke='%231a1a1a' stroke-width='1.8' stroke-linecap='round' opacity='.45'/%3E%3C/svg%3E") no-repeat bottom center/100% 7px;
  padding-bottom:12px;
}
.brand:hover{text-decoration:none;transform:rotate(-.5deg)}

.burger{justify-self:start}

.burger summary{
  display:inline-flex;
  align-items:center;
  gap:9px;
  list-style:none;
  cursor:pointer;
  min-height:44px;
  padding:9px 13px;
  font-size:16px;
  border:1.5px solid var(--ink);
  border-radius:16px 13px 17px 12px/12px 17px 13px 16px;
  background:var(--card);
  transform:rotate(-.8deg);
  user-select:none;
}
.burger summary::-webkit-details-marker{display:none}
.burger summary:hover{transform:rotate(.6deg)}

.bars{
  display:inline-block;
  width:15px;
  height:2px;
  background:var(--ink);
  box-shadow:0 -5px 0 var(--ink),0 5px 0 var(--ink);
}

.when-open{display:none}
.burger[open] .when-open{display:inline}
.burger[open] .when-closed{display:none}
.burger[open] summary{
  position:fixed;
  top:11px;
  left:16px;
  z-index:70;
  transform:none;
}

.burger menu{
  position:fixed;
  inset:0;
  z-index:60;
  margin:0;
  padding:82px 22px 30px;
  list-style:none;
  display:grid;
  grid-template-columns:1fr 1fr;
  grid-template-rows:repeat(4,auto);
  grid-auto-flow:column;
  gap:0 26px;
  align-content:start;
  overflow-y:auto;
  background-color:var(--paper);
  background-image:var(--grain);
  counter-reset:nav;
  animation:drop .18s steps(3) both;
}

@keyframes drop{from{opacity:0;transform:translateY(-8px)}to{opacity:1;transform:none}}

.burger menu li{counter-increment:nav}

.burger menu a{
  display:flex;
  align-items:center;
  min-height:54px;
  padding:11px 4px;
  font-size:clamp(17px,4.4vw,22px);
  line-height:1.3;
  border-bottom:1px dashed var(--line);
  letter-spacing:-.01em;
}
.burger menu a::before{
  content:counter(nav,decimal-leading-zero);
  font-size:16px;
  font-weight:400;
  color:var(--gray);
  margin-right:11px;
  font-variant-numeric:tabular-nums;
}
.burger menu a:hover,
.burger menu a:focus-visible{
  text-decoration:underline wavy .06em;
  text-underline-offset:6px;
  transform:translateX(3px) rotate(-.4deg);
}

.find{
  justify-self:end;
  display:flex;
  gap:6px;
  min-width:0;
}
.find input{
  width:100%;
  min-width:0;
  min-height:44px;
  padding:9px 12px;
  font-size:16px;
  background:var(--card);
  border:1.5px solid var(--line);
  border-radius:14px 11px 15px 10px/10px 15px 11px 14px;
}
.find input:focus-visible{outline:2px dashed var(--gray);outline-offset:2px}
.find button{
  min-height:44px;
  padding:9px 13px;
  font-size:16px;
  background:var(--ink);
  color:var(--paper);
  border:1.5px solid var(--ink);
  border-radius:15px 11px 14px 12px/12px 14px 11px 15px;
  cursor:pointer;
}
.find button:hover{background:var(--gray);border-color:var(--gray)}

/* ---------- 主视觉 ---------- */
.hero{
  position:relative;
  min-height:45vh;
  display:flex;
  flex-direction:column;
  justify-content:center;
  align-items:center;
  gap:20px;
  padding:38px 20px 0;
  text-align:center;
  overflow:hidden;
}
.hero-bg{
  position:absolute;
  inset:0;
  display:grid;
  place-items:center;
  font-size:clamp(150px,42vw,340px);
  font-weight:700;
  line-height:.9;
  letter-spacing:-.05em;
  color:var(--ink);
  opacity:.055;
  pointer-events:none;
  user-select:none;
}
.hero h1{
  position:relative;
  margin:0;
  max-width:16em;
  font-size:clamp(27px,5.6vw,52px);
  line-height:1.26;
  font-weight:700;
  letter-spacing:-.025em;
  text-wrap:balance;
}
.hero h1::after{
  content:"";
  display:block;
  width:min(230px,58%);
  height:11px;
  margin:14px auto 0;
  background:no-repeat center/100% 100% url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 200 12' preserveAspectRatio='none'%3E%3Cpath d='M3 8 Q 26 2 52 7 T 102 7 T 152 6 T 197 7' fill='none' stroke='%231a1a1a' stroke-width='2.6' stroke-linecap='round' opacity='.55'/%3E%3C/svg%3E");
}
.hero-fig{
  position:relative;
  width:100%;
  max-width:720px;
  margin-top:auto;
  transform:rotate(-.7deg);
}
.hero-fig img{
  width:100%;
  border:1.5px solid var(--line);
  border-radius:28px;
  box-shadow:0 16px 30px -20px rgba(26,26,26,.55);
  filter:grayscale(.22) contrast(1.03);
}

/* ---------- 主体栅格 ---------- */
.wrap{
  max-width:1140px;
  margin:0 auto;
  padding:46px 20px 64px;
  display:grid;
  grid-template-columns:232px minmax(0,1fr);
  gap:44px;
  align-items:start;
}

.side{
  position:sticky;
  top:86px;
  padding:18px 15px 20px;
  background:var(--card);
  border:1.5px dashed var(--line);
  border-radius:28px 22px 27px 21px/21px 27px 22px 28px;
  box-shadow:0 14px 26px -22px rgba(26,26,26,.6);
}
.side h2{
  margin:0 0 6px;
  font-size:16px;
  font-weight:700;
  letter-spacing:.16em;
}
.side .subtitle{
  margin:0 0 14px;
  font-size:16px;
  line-height:1.6;
  color:var(--gray);
  border-bottom:1px dashed var(--line-soft);
  padding-bottom:12px;
}
.toc{
  list-style:none;
  margin:0;
  padding:0;
  counter-reset:toc;
}
.toc li{counter-increment:toc}
.toc a{
  display:flex;
  align-items:center;
  min-height:40px;
  padding:6px 2px;
  font-size:16px;
  line-height:1.4;
  border-bottom:1px dashed var(--line-soft);
}
.toc a::before{
  content:counter(toc,decimal-leading-zero);
  color:var(--gray);
  margin-right:9px;
  font-size:13px;
  font-variant-numeric:tabular-nums;
}
.toc a:hover{text-decoration:underline wavy .06em;text-underline-offset:4px}

/* ---------- 正文 ---------- */
.prose{max-width:74ch}
.prose section{
  padding:30px 0;
  border-top:1.5px dashed var(--line);
  scroll-margin-top:110px;
}
.prose section:first-child{border-top:0;padding-top:0}
.prose h2{
  margin:0 0 10px;
  font-size:clamp(22px,3.4vw,30px);
  line-height:1.32;
  letter-spacing:-.015em;
}
.prose h3{
  margin:26px 0 8px;
  font-size:20px;
  line-height:1.4;
}
.prose p{margin:0 0 16px;color:#242424}
.prose .subtitle,
.prose .lead,
.prose p.subtitle{
  color:var(--gray);
  font-size:17px;
  line-height:1.7;
}
.prose ul,.prose ol{padding-left:1.35em;margin:0 0 18px}
.prose li{margin:.4em 0}
.prose li::marker{color:var(--gray)}
.prose strong{background:linear-gradient(transparent 64%,rgba(26,26,26,.13) 64%);font-weight:600}
.prose a{text-decoration:underline wavy .05em;text-underline-offset:4px}
.prose blockquote{
  margin:0 0 20px;
  padding:16px 18px;
  border:1.5px solid var(--line-soft);
  border-left:3px solid var(--ink);
  border-radius:36px 24px 34px 22px/22px 34px 24px 36px;
  background:var(--card);
  box-shadow:0 12px 24px -22px rgba(26,26,26,.6);
  color:var(--gray);
}
.prose blockquote p:last-child{margin-bottom:0}
.prose img{
  margin:18px 0;
  border:1.5px solid var(--line-soft);
  border-radius:22px;
  filter:grayscale(.15);
}
.prose code{
  font-size:.94em;
  padding:2px 6px;
  background:#efeeea;
  border-radius:7px;
}
.prose pre{
  overflow-x:auto;
  padding:14px 16px;
  background:#efeeea;
  border-radius:16px;
  font-size:16px;
}
.prose pre code{padding:0;background:none}
.prose table{
  width:100%;
  border-collapse:collapse;
  margin:0 0 20px;
  font-size:16px;
}
.prose th,.prose td{
  padding:10px 12px;
  text-align:left;
  border-bottom:1px solid var(--line-soft);
  vertical-align:top;
}
.prose th{font-weight:600;border-bottom:1.5px solid var(--line)}
.prose hr{border:0;border-top:1.5px dashed var(--line);margin:28px 0}

/* ---------- 页脚 ---------- */
.foot{
  border-top:1.5px solid var(--line);
  background-color:#f2f1ec;
  background-image:var(--grain);
  padding:42px max(20px,calc((100% - 1140px)/2)) 26px;
  display:grid;
  grid-template-columns:1.1fr 1fr 1.2fr;
  gap:30px;
  align-items:start;
}
.foot section{min-width:0}
.foot h2{
  margin:0 0 12px;
  font-size:16px;
  font-weight:700;
  letter-spacing:.16em;
}
.fmark{
  margin:0;
  font-size:19px;
  font-weight:700;
  line-height:1.45;
  letter-spacing:-.01em;
  transform:rotate(-.6deg);
  transform-origin:left top;
}
.fnav{
  list-style:none;
  margin:0;
  padding:0;
  columns:2;
  column-gap:16px;
}
.fnav a{
  display:block;
  min-height:40px;
  padding:6px 0;
  font-size:16px;
  line-height:1.4;
  border-bottom:1px dashed var(--line-soft);
}
.fnav li{break-inside:avoid}
.fnav a:hover{text-decoration:underline wavy .06em;text-underline-offset:4px}

.f-sub form{
  display:flex;
  flex-wrap:wrap;
  gap:8px;
}
.f-sub input{
  flex:1 1 130px;
  min-width:0;
  min-height:44px;
  padding:9px 12px;
  font-size:16px;
  background:var(--card);
  border:1.5px solid var(--line);
  border-radius:14px 11px 15px 10px/10px 15px 11px 14px;
}
.f-sub button{
  min-height:44px;
  padding:9px 16px;
  font-size:16px;
  background:var(--ink);
  color:var(--paper);
  border:1.5px solid var(--ink);
  border-radius:15px 11px 14px 12px/12px 14px 11px 15px;
  cursor:pointer;
}
.f-sub button:hover{background:var(--gray);border-color:var(--gray)}

.copy{
  grid-column:1/-1;
  margin-top:10px;
  padding-top:16px;
  border-top:1px dashed var(--line);
  text-align:center;
  color:var(--gray);
  font-size:16px;
}
.copy p{margin:0 0 4px}
.copy p:last-child{margin-bottom:0}

/* ---------- 进场 ---------- */
.reveal{opacity:0;transform:translateY(12px)}
.reveal.in{
  opacity:1;
  transform:none;
  transition:opacity .3s steps(3),transform .3s steps(3);
}

/* ---------- 断点 ---------- */
@media (max-width:960px){
  .wrap{grid-template-columns:1fr;gap:28px;padding-top:34px}
  .side{position:static}
  .toc{display:grid;grid-template-columns:1fr 1fr;gap:0 18px}
  .prose{max-width:none}
  .foot{grid-template-columns:1fr 1fr}
  .f-sub{grid-column:1/-1}
}

@media (max-width:700px){
  body{font-size:16.5px}
  .find button{display:none}
  .find{width:100%}
  .burger menu{gap:0 14px;padding-top:78px}
  .hero{min-height:45vh;padding-top:26px}
  .foot{grid-template-columns:1fr;gap:24px}
  .fnav{columns:1}
}

@media (max-width:400px){
  .burger summary{padding:9px 10px;gap:7px}
  .brand{font-size:14px}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal{opacity:1;transform:none;transition:none}
  .burger menu{animation:none}
  .brand:hover,.burger summary:hover,.fmark{transform:none}
}

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