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

:root{
  --ink:#1f1f1f;
  --paper:#ffffff;
  --mist:#f5f5f5;
  --mute:#6d6d6d;
  --line:rgba(31,31,31,.12);
  --e1:0 1px 2px rgba(31,31,31,.07),0 1px 1px rgba(31,31,31,.04);
  --e2:0 6px 16px rgba(31,31,31,.08),0 2px 4px rgba(31,31,31,.05);
  --e3:0 14px 34px rgba(31,31,31,.13),0 4px 10px rgba(31,31,31,.06);
  --e4:0 28px 64px rgba(31,31,31,.2),0 8px 20px rgba(31,31,31,.1);
  --r:10px;
}

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

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

body{
  margin:0;
  padding-bottom:92px;
  font-family:'Inter','Helvetica Neue',-apple-system,BlinkMacSystemFont,'Segoe UI','PingFang SC','Hiragino Sans GB','Microsoft YaHei',sans-serif;
  font-size:17px;
  line-height:1.72;
  color:var(--ink);
  background:var(--mist);
  overflow-x:hidden;
}

a{color:inherit}
img{max-width:100%}

/* ---------- 斜切叠层 hero ---------- */
.hero{
  position:relative;
  isolation:isolate;
  min-height:70vh;
  display:grid;
  align-content:end;
  padding:104px 0 88px;
  background:#151515;
  color:#fff;
  overflow:hidden;
  clip-path:polygon(0 0,100% 0,100% 92%,0 100%);
}

.hero-media{
  position:absolute;
  inset:0;
  z-index:-2;
}

.hero-media img{
  display:block;
  width:100%;
  height:100%;
  object-fit:cover;
  opacity:.62;
  transform:scale(1.06);
  will-change:transform;
}

.hero::after{
  content:"";
  position:absolute;
  inset:0;
  z-index:-1;
  background:linear-gradient(200deg,rgba(21,21,21,.12) 0%,rgba(21,21,21,.55) 46%,rgba(21,21,21,.94) 100%);
}

.hero-slab{
  position:relative;
  z-index:1;
  width:100%;
  max-width:1180px;
  margin:0 auto;
  padding:0 22px;
  text-align:right;
}

.hero h1{
  margin:0 0 0 auto;
  max-width:16em;
  font-size:clamp(30px,6.2vw,58px);
  line-height:1.14;
  letter-spacing:-.02em;
  font-weight:600;
  text-wrap:balance;
}

.hero-sub{
  margin:16px 0 0 auto;
  max-width:48ch;
  font-size:16px;
  line-height:1.65;
  color:rgba(255,255,255,.78);
}

/* ---------- 主体：左栏 + 正文 ---------- */
main{display:block}

.wrap{
  display:grid;
  grid-template-columns:250px minmax(0,1fr);
  align-items:start;
  gap:26px;
  max-width:1180px;
  margin:0 auto;
  padding:30px 22px 52px;
}

.wrap > article{min-width:0;position:relative;z-index:1}

/* 侧栏索引 */
.side{
  position:sticky;
  top:18px;
  z-index:2;
  background:var(--paper);
  border:1px solid var(--line);
  border-radius:var(--r);
  box-shadow:var(--e2);
  padding:16px 14px 18px;
}

.side h2{
  margin:0 0 12px;
  font-size:16px;
  font-weight:600;
  letter-spacing:-.01em;
}

.side-list{
  list-style:none;
  margin:0;
  padding:0;
}

.side-list a{
  display:flex;
  align-items:center;
  gap:8px;
  min-height:42px;
  padding:6px 8px;
  border-left:2px solid transparent;
  border-radius:0 8px 8px 0;
  font-size:15px;
  text-decoration:none;
  color:#3a3a3a;
  transition:background .2s,border-color .2s,transform .2s;
}

.side-list .num{
  flex:none;
  width:18px;
  font-size:12px;
  font-weight:600;
  color:#9a9a9a;
  font-variant-numeric:tabular-nums;
}

.side-list a:hover{
  background:var(--mist);
  border-left-color:var(--ink);
  transform:translateX(2px);
}

/* 眉题 */
small,
.eyebrow{
  display:block;
  margin:0 0 6px;
  font-size:13px;
  font-weight:600;
  letter-spacing:.16em;
  color:#8a8a8a;
}

/* ---------- 正文卡片叠层 ---------- */
.body > div > article{
  position:relative;
  z-index:1;
  margin:0 0 24px;
  padding:26px 24px 30px;
  background:var(--paper);
  border:1px solid var(--line);
  border-radius:var(--r);
  box-shadow:var(--e2);
  transform:translateZ(0);
  scroll-margin-top:24px;
  transition:box-shadow .28s ease,transform .28s ease;
}

.body > div > article::before{
  content:"";
  position:absolute;
  left:24px;
  right:24px;
  top:0;
  height:2px;
  border-radius:2px;
  background:linear-gradient(90deg,var(--ink),rgba(31,31,31,0));
  opacity:.5;
}

.body > div > article + article{margin-top:-10px}

.body > div > article:hover{
  box-shadow:var(--e3);
  transform:translateY(-2px);
}

.body > div > article:nth-child(3n+2){
  box-shadow:var(--e3);
}

.body > div > article:nth-child(3n+2):hover{
  box-shadow:var(--e4);
}

/* 正文排版 */
.body h2{
  margin:0 0 14px;
  font-size:clamp(22px,3.2vw,30px);
  line-height:1.3;
  letter-spacing:-.015em;
  font-weight:600;
}

.body h3{
  margin:24px 0 10px;
  font-size:19px;
  line-height:1.4;
  font-weight:600;
}

.body h4{
  margin:20px 0 8px;
  font-size:17px;
  font-weight:600;
}

.body p{margin:0 0 14px}
.body p:last-child{margin-bottom:0}

.body ul,
.body ol{margin:0 0 16px;padding-left:1.25em}
.body li{margin-bottom:7px}

.body a{
  color:var(--ink);
  text-decoration:underline;
  text-decoration-thickness:1px;
  text-underline-offset:3px;
  text-decoration-color:rgba(31,31,31,.4);
}
.body a:hover{text-decoration-color:var(--ink)}

.body strong{font-weight:600}
.body em{font-style:normal;color:var(--mute)}

.body blockquote{
  margin:0 0 16px;
  padding:12px 16px;
  border-left:3px solid var(--ink);
  border-radius:0 8px 8px 0;
  background:var(--mist);
  box-shadow:var(--e1);
}

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

.body img{
  display:block;
  height:auto;
  border-radius:8px;
  box-shadow:var(--e2);
  margin:6px 0 16px;
}

.body figure{margin:0 0 16px}

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

.body th,
.body td{
  padding:9px 10px;
  border-bottom:1px solid var(--line);
  text-align:left;
  vertical-align:top;
}

.body th{background:var(--mist);font-weight:600}

.body hr{
  height:1px;
  border:0;
  margin:22px 0;
  background:var(--line);
}

/* ---------- 底部固定条 ---------- */
.bar{
  position:fixed;
  left:0;
  right:0;
  bottom:0;
  z-index:40;
  display:flex;
  align-items:center;
  gap:10px;
  padding:8px 12px;
  background:rgba(255,255,255,.84);
  -webkit-backdrop-filter:blur(14px);
  backdrop-filter:blur(14px);
  border-top:1px solid var(--line);
  box-shadow:var(--e4);
}

.brand{
  flex:none;
  display:grid;
  place-items:center;
  width:42px;
  height:42px;
  border-radius:12px;
  background:var(--ink);
  color:#fff;
  font-size:16px;
  font-weight:700;
  text-decoration:none;
  box-shadow:var(--e2);
}

.brand img,
.brand .mark-img{
  display:block;
  width:22px;
  height:22px;
  object-fit:contain;
}

.tabs{
  flex:1 1 auto;
  min-width:0;
  overflow-x:auto;
  scrollbar-width:none;
  -ms-overflow-style:none;
}

.tabs::-webkit-scrollbar{display:none}

.tabs p{
  display:flex;
  align-items:center;
  gap:2px;
  margin:0;
  white-space:nowrap;
}

.tabs a{
  display:inline-flex;
  align-items:center;
  min-height:42px;
  padding:0 11px;
  border-radius:9px;
  font-size:15px;
  text-decoration:none;
  color:#3a3a3a;
  transition:background .2s,color .2s;
}

.tabs a:hover{background:var(--mist);color:var(--ink)}
.tabs a.on{background:var(--ink);color:#fff}

.find{
  flex:none;
  display:flex;
  align-items:center;
  gap:6px;
}

.find input{
  width:104px;
  height:40px;
  padding:0 11px;
  border:1px solid var(--line);
  border-radius:10px;
  background:#fff;
  font:inherit;
  font-size:15px;
  color:var(--ink);
}

.find input:focus{
  outline:2px solid rgba(31,31,31,.35);
  outline-offset:1px;
}

.find button{
  height:40px;
  min-width:46px;
  border:1px solid var(--ink);
  border-radius:10px;
  background:var(--ink);
  color:#fff;
  font:inherit;
  font-size:15px;
  cursor:pointer;
}

.find button:hover{background:#000}

/* ---------- 页脚 ---------- */
.foot{
  position:relative;
  z-index:3;
  margin-top:24px;
  padding:40px 22px 24px;
  background:var(--ink);
  color:#e9e9e9;
}

.foot-main{
  display:grid;
  grid-template-columns:1fr 1fr;
  gap:24px;
  align-items:start;
  max-width:1180px;
  margin:0 auto;
}

.foot address{
  font-style:normal;
  font-size:20px;
  font-weight:600;
  letter-spacing:-.01em;
}

.foot-links ul{
  display:flex;
  flex-wrap:wrap;
  justify-content:flex-end;
  gap:4px 18px;
  list-style:none;
  margin:0;
  padding:0;
}

.foot-links a{
  display:inline-flex;
  align-items:center;
  min-height:42px;
  font-size:15px;
  color:#d5d5d5;
  text-decoration:none;
  border-bottom:1px solid transparent;
}

.foot-links a:hover{
  color:#fff;
  border-bottom-color:rgba(255,255,255,.45);
}

.foot-copy{
  max-width:1180px;
  margin:20px auto 0;
  padding-top:14px;
  border-top:1px solid rgba(255,255,255,.14);
  text-align:center;
  font-size:13px;
  color:#a8a8a8;
}

/* ---------- 断点 ---------- */
@media (max-width:900px){
  .wrap{
    grid-template-columns:minmax(0,1fr);
    gap:16px;
    padding:20px 16px 44px;
  }
  .side{position:static}
  .side h2{margin-bottom:8px}
  .side-list{
    display:flex;
    gap:8px;
    overflow-x:auto;
    padding-bottom:4px;
    scrollbar-width:none;
  }
  .side-list::-webkit-scrollbar{display:none}
  .side-list li{flex:none}
  .side-list .num{display:none}
  .side-list a{
    min-height:40px;
    padding:6px 12px;
    border-left:0;
    border-bottom:2px solid transparent;
    border-radius:8px;
    background:var(--mist);
  }
  .side-list a:hover{transform:none;border-left:0;border-bottom-color:var(--ink)}
  .foot-main{grid-template-columns:1fr;gap:12px}
  .foot-links ul{justify-content:flex-start}
}

@media (max-width:640px){
  body{padding-bottom:86px;font-size:16px}
  .hero{min-height:64vh;padding:88px 0 72px}
  .hero-slab{padding:0 16px}
  .hero-sub{font-size:15px}
  .find input{display:none}
  .body > div > article{padding:22px 16px 26px}
  .body > div > article::before{left:16px;right:16px}
  .body > div > article + article{margin-top:-8px}
  .foot{padding:32px 16px 20px}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *{transition:none !important;animation:none !important}
  .hero-media img{transform:none}
  .body > div > article:hover{transform:none}
}

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