@import url('https://fonts.googleapis.com/css2?family=Atkinson+Hyperlegible:wght@400;700&display=swap');

:root{
  --ink:#000000;
  --paper:#ffffff;
  --line:#000000;
  --mute:#4d4d4d;
  --soft:#f2f2f2;
  --r:10px;
  --stack:"Atkinson Hyperlegible","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,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(--stack);font-size:17px;line-height:1.65;
  font-weight:400;letter-spacing:.005em;
  overflow-x:hidden;
}
img{max-width:100%;height:auto;display:block}
a{color:var(--ink)}
p{margin:0 0 1em}
h1,h2,h3,h4{font-weight:700;letter-spacing:-.02em;line-height:1.18}

/* ---------- 顶栏 ---------- */
.topbar{position:sticky;top:0;z-index:60;background:var(--paper);border-bottom:2px solid var(--line)}
.masthead{
  display:grid;grid-template-columns:1fr auto 1fr;align-items:center;
  gap:10px;padding:8px 16px;min-height:62px;
}
.masthead__side{display:flex;align-items:center;gap:2px;min-width:0}
.masthead__side--r{justify-content:flex-end}
.masthead__link{
  display:inline-flex;align-items:center;min-height:42px;padding:0 9px;
  font-size:15px;text-decoration:none;border-bottom:2px solid transparent;white-space:nowrap;
}
.masthead__link:hover{border-bottom-color:var(--line)}
.brand{
  display:inline-flex;align-items:center;gap:8px;text-decoration:none;
  font-weight:700;font-size:18px;letter-spacing:-.03em;white-space:nowrap;
}
.brand__mark{
  display:inline-grid;place-items:center;width:30px;height:30px;
  border:2px solid var(--line);border-radius:50%;font-size:14px;line-height:1;
}
.brand__logo{width:30px;height:30px;border-radius:50%;object-fit:cover}
.cta{
  display:inline-flex;align-items:center;min-height:42px;padding:0 16px;margin-left:6px;
  background:var(--ink);color:var(--paper);text-decoration:none;
  border-radius:var(--r);font-size:15px;font-weight:700;white-space:nowrap;
}
.cta:hover{background:#2b2b2b}
.burger{
  width:44px;height:44px;padding:0;margin-right:4px;cursor:pointer;
  display:grid;place-content:center;gap:4px;
  border:2px solid var(--line);border-radius:var(--r);background:var(--paper);
}
.burger span{display:block;width:17px;height:2px;background:var(--ink)}

/* ---------- 二级锚点条 ---------- */
.anchorbar{
  display:flex;overflow-x:auto;background:var(--ink);color:var(--paper);
  border-top:1px solid #2b2b2b;scrollbar-width:none;
}
.anchorbar::-webkit-scrollbar{display:none}
.anchorbar a{
  flex:0 0 auto;display:inline-flex;align-items:center;min-height:40px;
  padding:0 14px;color:#e9e9e9;text-decoration:none;font-size:13px;
  border-right:1px solid #333;white-space:nowrap;
}
.anchorbar a:hover,.anchorbar a.on{background:var(--paper);color:var(--ink);font-weight:700}

/* ---------- 全屏菜单 ---------- */
.menu{
  position:fixed;inset:0;z-index:90;display:flex;flex-direction:column;
  background:var(--ink);color:var(--paper);padding:18px 20px 26px;
  overflow-y:auto;transform:translateY(-101%);visibility:hidden;
  transition:transform .42s cubic-bezier(.2,.75,.2,1),visibility .42s;
}
.menu.is-open{transform:none;visibility:visible}
.menu__top{display:flex;align-items:center;justify-content:space-between;gap:16px}
.menu__head{margin:0;font-size:13px;letter-spacing:.16em}
.menu__close{
  width:46px;height:46px;background:none;color:var(--paper);cursor:pointer;
  border:2px solid var(--paper);border-radius:var(--r);font-size:22px;line-height:1;
}
.menu__nav{margin-top:14px;flex:1 1 auto}
.menu__nav ul{list-style:none;margin:0;padding:0}
.menu__nav a{
  display:flex;align-items:center;min-height:56px;padding:6px 0;
  color:var(--paper);text-decoration:none;font-size:clamp(22px,5.4vw,38px);
  font-weight:700;letter-spacing:-.03em;border-bottom:1px solid #2e2e2e;
}
.menu__nav a:hover{color:#cfcfcf}
.menu__foot{margin:18px 0 0;font-size:13px;color:#9a9a9a;letter-spacing:.12em}

/* ---------- Hero ---------- */
.hero{
  position:relative;min-height:70vh;display:flex;align-items:flex-end;
  overflow:hidden;background:var(--ink);color:var(--paper);isolation:isolate;
}
.hero__media{position:absolute;inset:0;z-index:-2}
.hero__media img{width:100%;height:100%;object-fit:cover;filter:grayscale(1) contrast(1.08)}
.hero__mask{
  position:absolute;inset:0;z-index:-1;
  background:
    repeating-linear-gradient(0deg,rgba(255,255,255,.09) 0 1px,transparent 1px 36px),
    repeating-linear-gradient(90deg,rgba(255,255,255,.09) 0 1px,transparent 1px 36px),
    linear-gradient(to top,rgba(0,0,0,.94) 6%,rgba(0,0,0,.5) 58%,rgba(0,0,0,.78));
}
.hero__inner{position:relative;width:100%;max-width:1120px;margin:0 auto;padding:64px 18px 42px;text-align:left}
.hero__kicker{
  margin:0;font-size:12px;letter-spacing:.34em;text-transform:uppercase;color:#dcdcdc;
}
.hero h1{
  margin:.28em 0 .34em;font-size:clamp(30px,7.4vw,66px);line-height:1.03;
  letter-spacing:-.035em;max-width:16em;
}
.hero__lede{
  margin:0;font-size:clamp(15px,2.1vw,18px);line-height:1.6;color:#e6e6e6;max-width:34em;
}

/* ---------- 版心与不对称栅格 ---------- */
.wrap{max-width:1180px;margin:0 auto;padding:0 18px}
.spread{
  display:grid;grid-template-columns:216px minmax(0,1fr);
  gap:40px;align-items:start;padding:46px 0 12px;
}
article section{scroll-margin-top:132px}

/* ---------- 左侧目录 ---------- */
.rail{position:sticky;top:126px;border-top:5px solid var(--line);padding-top:14px}
.rail__t{margin:0 0 12px;font-size:12px;letter-spacing:.3em;text-transform:uppercase}
.rail__nav ul{list-style:none;margin:0;padding:0}
.rail__nav li + li{border-top:1px solid #e3e3e3}
.rail__nav a{
  display:flex;align-items:center;min-height:42px;padding:6px 0;
  font-size:15px;text-decoration:none;line-height:1.3;
}
.rail__nav a:hover{text-decoration:underline;text-underline-offset:4px;text-decoration-thickness:2px}
.rail__s{margin:22px 0 5px;font-size:11px;letter-spacing:.28em;text-transform:uppercase;color:var(--mute)}
.rail__p{margin:0;font-size:14px;line-height:1.5;color:var(--mute)}

/* ---------- 正文 ---------- */
.prose{min-width:0;counter-reset:sec}
.prose > section{
  counter-increment:sec;position:relative;
  background:var(--paper);border-radius:var(--r);
  box-shadow:0 8px 22px rgba(0,0,0,.09);
  padding:26px 24px 20px;margin:0 0 26px;
}
.prose > section:nth-child(even){margin-left:7%}
.prose > section::after{
  content:counter(sec,decimal-leading-zero);
  position:absolute;top:12px;right:16px;
  font-size:12px;letter-spacing:.14em;color:#b4b4b4;
}
.prose h2{
  font-size:clamp(21px,3vw,30px);line-height:1.14;margin:0 0 .5em;
  padding-bottom:.4em;border-bottom:2px solid var(--line);
}
.prose h2 > span{display:inline}
.prose h3{font-size:clamp(18px,2.2vw,22px);margin:1.4em 0 .5em}
.prose p{max-width:66ch}
.prose ul,.prose ol{padding-left:1.25em;max-width:64ch}
.prose li{margin:.35em 0}
.prose a{text-decoration:underline;text-underline-offset:3px;text-decoration-thickness:1.5px}
.prose > section:first-child > p:first-of-type::first-letter{
  float:left;font-size:3.5em;line-height:.82;font-weight:700;
  padding:.05em .12em 0 0;
}
.prose blockquote{
  margin:26px 0;padding:16px 20px;background:var(--soft);
  border-left:6px solid var(--line);font-size:1.04em;
}
.prose blockquote p{margin:.35em 0}
.prose blockquote p:last-child{margin-bottom:0}
.prose figure{margin:24px 0}
.prose figure img{border-radius:var(--r)}
.prose figcaption{font-size:13px;color:var(--mute);margin-top:8px;line-height:1.5}
.prose hr{border:0;border-top:2px solid var(--line);margin:28px 0}
.prose table{width:100%;border-collapse:collapse;font-size:16px}
.prose th,.prose td{border-bottom:1px solid #d8d8d8;padding:9px 6px;text-align:left}
.prose code{font-size:.94em;background:var(--soft);padding:.1em .35em;border-radius:4px}

/* ---------- 订阅带 ---------- */
.band{background:var(--ink);color:var(--paper);padding:44px 18px;margin-top:26px}
.band__t{margin:0 0 14px;font-size:clamp(22px,3.6vw,34px)}
.band__label{
  position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;
}
.band__form{display:flex;flex-wrap:wrap;gap:10px;max-width:560px}
.band__form input{
  flex:1 1 220px;min-height:50px;padding:0 14px;font:inherit;font-size:16px;
  color:var(--paper);background:#111;border:2px solid #6d6d6d;border-radius:var(--r);
}
.band__form input::placeholder{color:#a6a6a6}
.band__form input:focus{outline:2px solid var(--paper);outline-offset:2px;border-color:var(--paper)}
.band__form button{
  min-height:50px;padding:0 26px;font:inherit;font-size:16px;font-weight:700;cursor:pointer;
  color:var(--ink);background:var(--paper);border:2px solid var(--paper);border-radius:var(--r);
}
.band__form button:hover{background:#d9d9d9;border-color:#d9d9d9}

/* ---------- 页脚 ---------- */
.foot{
  display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);
  gap:16px 28px;padding:34px 18px 40px;border-top:2px solid var(--line);
}
.foot__brand{margin:0;font-size:15px;line-height:1.55;max-width:32em}
.foot__brand strong{display:block;font-size:17px;letter-spacing:-.02em;margin-bottom:4px}
.foot__links{margin:0;font-size:15px;text-align:right;line-height:1.9}
.foot__links a{text-decoration:none;border-bottom:1.5px solid var(--line)}
.foot__copy,.foot__top{font-size:13px;color:var(--mute);align-self:end}
.foot__top{text-align:right;margin:0}
.foot__top a{color:var(--mute);text-decoration:none}
.foot__top a:hover{color:var(--ink)}

.totop{
  position:fixed;right:16px;bottom:16px;z-index:55;
  display:grid;place-items:center;width:46px;height:46px;border-radius:50%;
  background:var(--ink);color:var(--paper);text-decoration:none;font-size:18px;
  box-shadow:0 6px 18px rgba(0,0,0,.28);
}
.totop:hover{background:#2b2b2b}

/* ---------- 滚动显现 ---------- */
.rv{opacity:0;transform:translateY(16px);transition:opacity .55s ease,transform .55s ease}
.rv.is-in{opacity:1;transform:none}

/* ---------- 断点 ---------- */
@media (max-width:1000px){
  .masthead__link{display:none}
  .spread{grid-template-columns:1fr;gap:26px;padding-top:30px}
  .rail{position:static;top:auto}
  .rail__nav ul{display:grid;grid-template-columns:1fr 1fr;gap:0 16px;border-bottom:1px solid #e3e3e3}
  .rail__nav li + li{border-top:0}
  .rail__nav li{border-top:1px solid #e3e3e3}
  .rail__s,.rail__p{display:none}
  .prose > section:nth-child(even){margin-left:0}
}
@media (max-width:640px){
  body{font-size:16.5px}
  .cta{display:none}
  .masthead{min-height:58px;padding:6px 14px}
  .brand{font-size:17px}
  .hero{min-height:66vh}
  .hero__inner{padding:52px 16px 34px}
  .wrap{padding:0 14px}
  .prose > section{padding:22px 18px 16px;box-shadow:0 6px 16px rgba(0,0,0,.1)}
  .foot{grid-template-columns:1fr;gap:14px}
  .foot__links{text-align:left}
  .foot__top{text-align:left}
  .band__form button{flex:1 1 100%}
  .totop{right:12px;bottom:12px}
}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .rv{opacity:1;transform:none;transition:none}
  .menu{transition:none}
}

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