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

:root{
  --ink:#000000;
  --paper:#ffffff;
  --line:rgba(0,0,0,.16);
  --hair:rgba(0,0,0,.09);
  --muted:rgba(0,0,0,.6);
  --rail-w:236px;
  --bar-h:66px;
  --head:'Playfair Display SC','Songti SC',Georgia,'Times New Roman',serif;
  --body:'Karla','Helvetica Neue',Arial,'PingFang SC','Microsoft YaHei',sans-serif;
}

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

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

body{
  margin:0;
  padding-top:var(--bar-h);
  background:var(--paper);
  color:var(--ink);
  font-family:var(--body);
  font-size:17px;
  line-height:1.75;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}

img{display:block;max-width:100%;height:auto}
a{color:inherit}
ul,ol{margin:0}
p{margin:0 0 1.1em}
:focus-visible{outline:2px solid var(--ink);outline-offset:3px}

small{
  display:block;
  font-family:var(--body);
  font-size:12px;
  font-weight:600;
  letter-spacing:.26em;
  color:var(--muted);
  margin:0 0 10px;
}

/* ---------- 左侧固定栏 / 移动端顶栏 ---------- */
.rail{
  position:fixed;
  top:0;
  left:0;
  right:0;
  z-index:60;
  display:flex;
  align-items:center;
  gap:10px;
  padding:9px 14px;
  background:rgba(255,255,255,.94);
  -webkit-backdrop-filter:blur(14px);
  backdrop-filter:blur(14px);
  border-bottom:1px solid var(--ink);
  overflow-x:auto;
  overflow-y:hidden;
  scrollbar-width:none;
}
.rail::-webkit-scrollbar{display:none}

.brand{
  font-family:var(--head);
  font-size:20px;
  line-height:1;
  letter-spacing:.06em;
  text-decoration:none;
  white-space:nowrap;
  padding:10px 0;
  flex:0 0 auto;
}

.rail-nav{flex:0 0 auto}
.rail-nav ul{display:flex;gap:6px;padding:0;list-style:none}
.rail-nav a{
  display:flex;
  align-items:center;
  min-height:40px;
  padding:0 14px;
  border:1px solid var(--ink);
  border-radius:999px;
  font-size:14px;
  letter-spacing:.03em;
  text-decoration:none;
  white-space:nowrap;
  transition:background-color .22s ease,color .22s ease;
}
.rail-nav a:hover,
.rail-nav a:focus-visible{background:var(--ink);color:var(--paper)}

.rail-contact{
  display:flex;
  align-items:center;
  min-height:40px;
  padding:0 15px;
  border-radius:999px;
  background:var(--ink);
  color:var(--paper);
  font-size:14px;
  letter-spacing:.06em;
  text-decoration:none;
  white-space:nowrap;
  flex:0 0 auto;
}

/* ---------- Hero ---------- */
.hero{
  position:relative;
  display:grid;
  place-items:center;
  min-height:100vh;
  min-height:100svh;
  padding:88px 22px;
  background:var(--ink);
  color:var(--paper);
  text-align:center;
  overflow:hidden;
}

.hero-media{
  position:absolute;
  inset:-12% 0;
  overflow:hidden;
  will-change:transform;
}
.hero-img{width:100%;height:100%;object-fit:cover}
.hero-mask{position:absolute;inset:0;background:rgba(0,0,0,.55)}

.hero-text{position:relative;max-width:920px}
.hero h1{
  margin:0;
  font-family:var(--head);
  font-weight:400;
  font-size:clamp(2rem,6vw,4.2rem);
  line-height:1.12;
  letter-spacing:.02em;
}
.hero-lead{
  max-width:38em;
  margin:24px auto 0;
  font-size:17px;
  line-height:1.72;
  color:rgba(255,255,255,.86);
}

/* ---------- 主体网格 ---------- */
.wrap{
  max-width:1180px;
  margin:0 auto;
  padding:60px 22px 76px;
  display:grid;
  gap:44px;
}

div{max-width:44rem}
div > article{
  padding:38px 0;
  border-top:1px solid var(--ink);
  scroll-margin-top:calc(var(--bar-h) + 20px);
}
div > article:first-child{border-top:0;padding-top:0}

div h2{
  margin:0 0 .55em;
  font-family:var(--head);
  font-weight:400;
  font-size:clamp(1.45rem,2.4vw,2rem);
  line-height:1.22;
  letter-spacing:.01em;
}
div h3{
  margin:1.6em 0 .5em;
  font-family:var(--head);
  font-weight:400;
  font-size:1.2rem;
  line-height:1.3;
}
div ul,
div ol{padding-left:1.15em;margin:0 0 1.1em}
div li{margin:.32em 0}
div a{text-decoration:underline;text-underline-offset:3px}
div img{border-radius:4px;margin:1.2em 0}
div figure{margin:1.4em 0}
div blockquote{
  margin:1.4em 0;
  padding:2px 0 2px 18px;
  border-left:2px solid var(--ink);
  color:var(--muted);
}
div table{width:100%;border-collapse:collapse;margin:1.4em 0;font-size:16px}
div th,
div td{border-bottom:1px solid var(--line);padding:10px 12px;text-align:left;vertical-align:top}
div th{font-weight:700;border-bottom-color:var(--ink)}
div code{
  font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  font-size:.92em;
  background:rgba(0,0,0,.06);
  padding:1px 5px;
  border-radius:2px;
}
div hr{border:0;border-top:1px solid var(--line);margin:2em 0}

/* ---------- 右侧栏 ---------- */
.side{
  padding:22px 20px;
  background:rgba(255,255,255,.62);
  -webkit-backdrop-filter:blur(12px);
  backdrop-filter:blur(12px);
  border:1px solid var(--line);
  border-radius:4px;
}
.side h2{
  margin:0 0 14px;
  font-family:var(--head);
  font-weight:400;
  font-size:1.32rem;
  line-height:1.25;
}
.side-nav ul{list-style:none;padding:0}
.side-nav a{
  display:flex;
  align-items:center;
  min-height:40px;
  font-size:15px;
  line-height:1.35;
  text-decoration:none;
  border-bottom:1px solid var(--hair);
  transition:padding-left .22s ease,color .22s ease;
}
.side-nav a:hover,
.side-nav a:focus-visible{padding-left:8px;color:var(--ink)}
.side-nav li:last-child a{border-bottom:0}

.to-top{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  margin-top:16px;
  font-size:14px;
  letter-spacing:.06em;
  text-decoration:none;
  border-bottom:1px solid var(--ink);
}

/* ---------- 页脚 ---------- */
footer{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:space-between;
  gap:6px 30px;
  padding:24px 22px 36px;
  border-top:1px solid var(--ink);
}
.f-brand a{
  font-family:var(--head);
  font-size:18px;
  letter-spacing:.05em;
  text-decoration:none;
}
.f-nav ul{
  display:flex;
  flex-wrap:wrap;
  gap:0 16px;
  list-style:none;
  padding:0;
}
.f-nav a{
  display:flex;
  align-items:center;
  min-height:40px;
  font-size:14px;
  color:var(--muted);
  text-decoration:none;
  transition:color .22s ease;
}
.f-nav a:hover,
.f-nav a:focus-visible{color:var(--ink)}
.f-copy{font-size:13px;letter-spacing:.08em;color:var(--muted)}

/* ---------- 动效 ---------- */
.reveal{
  opacity:0;
  transform:translate3d(0,16px,0);
  transition:opacity .5s ease,transform .5s ease;
}
.reveal.in{opacity:1;transform:none}

/* ---------- 桌面 ---------- */
@media (min-width:861px){
  body{padding-top:0;padding-left:var(--rail-w)}

  .rail{
    right:auto;
    bottom:0;
    width:var(--rail-w);
    height:100%;
    flex-direction:column;
    align-items:stretch;
    gap:0;
    padding:30px 22px 26px;
    background:var(--paper);
    -webkit-backdrop-filter:none;
    backdrop-filter:none;
    border-bottom:0;
    border-right:1px solid var(--ink);
    overflow:visible;
  }
  .brand{font-size:24px;padding:0;margin-bottom:28px}
  .rail-nav ul{flex-direction:column;gap:8px}
  .rail-nav a{justify-content:flex-start;min-height:44px;padding:0 16px;font-size:15px}
  .rail-contact{margin-top:auto;justify-content:center;min-height:44px}

  .wrap{grid-template-columns:minmax(0,1fr) 264px;gap:52px;padding:88px 40px 104px}
  .side{position:sticky;top:24px}
  div > article{scroll-margin-top:28px;padding:44px 0}
  footer{padding:26px 40px 38px}
}

@media (min-width:1200px){
  .wrap{padding-left:56px;padding-right:56px}
  footer{padding-left:56px;padding-right:56px}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal{opacity:1;transform:none;transition:none}
  .hero-media{transform:none !important}
}

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