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

:root{
  --red:#FF4D3D;
  --ink:#1B1E2B;
  --paper:#F4F1EA;
  --hdr:64px;
  --edge:2px solid var(--ink);
}

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

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

body{
  margin:0;
  padding-top:var(--hdr);
  background:var(--paper);
  color:var(--ink);
  font-family:"Space Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  font-size:17px;
  line-height:1.7;
}

h1,h2,h3,h4{font-weight:700;letter-spacing:-.01em;margin:0;}
p{margin:0 0 16px;}
a{color:inherit;}
ol,ul{list-style:none;margin:0;padding:0;}
img{display:block;max-width:100%;height:auto;}
button{font-family:inherit;}

section[id]{scroll-margin-top:calc(var(--hdr) + 64px);}

body.menu-open{overflow:hidden;}

/* ── 顶栏 ── */
.top{
  position:fixed;top:0;left:0;right:0;height:var(--hdr);z-index:70;
  display:flex;align-items:center;justify-content:space-between;
  padding:0 12px;
  background:var(--ink);
  border-bottom:3px solid var(--red);
}
.mark{
  display:inline-flex;align-items:center;justify-content:center;
  width:44px;height:44px;background:var(--red);border-radius:4px;
  text-decoration:none;
}
.mark svg{display:block;}
.tools{display:flex;align-items:center;gap:10px;}
.contact{
  display:inline-flex;align-items:center;min-height:44px;padding:0 15px;
  color:var(--paper);border:2px solid var(--paper);border-radius:4px;
  font-size:15px;font-weight:700;text-decoration:none;line-height:1;
  transition:background .16s ease,color .16s ease;
}
.contact:hover,.contact:focus-visible{background:var(--paper);color:var(--ink);}
.burger{
  min-height:44px;min-width:66px;padding:0 14px;
  background:var(--red);color:var(--ink);
  border:2px solid var(--red);border-radius:4px;
  font-size:15px;font-weight:700;line-height:1;cursor:pointer;
  transition:background .16s ease,color .16s ease,border-color .16s ease;
}
.burger:hover,.burger:focus-visible{background:var(--paper);border-color:var(--paper);}
.burger[aria-expanded="true"]{background:var(--paper);border-color:var(--paper);color:var(--ink);}

/* ── 全屏遮罩菜单 ── */
.drawer{
  position:fixed;inset:0;z-index:60;
  background:var(--ink);
  padding:calc(var(--hdr) + 26px) 20px 40px;
  overflow-y:auto;
  visibility:hidden;opacity:0;
  transition:opacity .16s ease,visibility .16s ease;
}
.drawer.open{visibility:visible;opacity:1;}
.drawer-nav .drawer-list{display:block;}
.drawer-list li{border-bottom:2px solid #2E3345;}
.drawer-list a{
  display:flex;align-items:center;min-height:56px;padding:8px 0;
  color:var(--paper);text-decoration:none;
  font-size:clamp(19px,5.4vw,28px);font-weight:700;line-height:1.25;
  transition:color .16s ease;
}
.drawer-list a:hover,.drawer-list a:focus-visible{color:var(--red);}
.drawer-top{
  display:inline-flex;align-items:center;min-height:44px;margin-top:26px;padding:0 16px;
  background:var(--red);color:var(--ink);border-radius:4px;
  font-size:15px;font-weight:700;text-decoration:none;
}

/* ── Hero ── */
.hero{
  position:relative;
  min-height:calc(100svh - var(--hdr) + 64px);
  display:flex;align-items:flex-end;
  padding:24px 20px 112px;
  background:var(--ink);
  overflow:hidden;
  clip-path:polygon(0 0,100% 0,100% calc(100% - 64px),0 100%);
}
.hero-copy{position:relative;z-index:2;max-width:1000px;}
.hero-copy small{
  display:block;margin-bottom:14px;
  color:var(--red);font-size:14px;font-weight:700;letter-spacing:.28em;
}
.hero-copy h1{
  margin:0;color:var(--paper);
  font-size:clamp(32px,7.4vw,86px);line-height:1.05;letter-spacing:-.025em;
}
.hero-copy p{
  margin:18px 0 0;max-width:46ch;
  color:var(--paper);opacity:.85;font-size:16px;
}
.hero-art{position:absolute;inset:0;z-index:1;margin:0;}
.hero-art img{
  position:absolute;inset:0;width:100%;height:100%;max-width:none;
  object-fit:cover;opacity:0;
  transition:opacity .7s ease;
}
.hero-art img.on{opacity:.62;}

/* ── 粘性锚点条 ── */
.jump{
  position:sticky;top:var(--hdr);z-index:45;
  background:var(--red);
  border-bottom:3px solid var(--ink);
}
.jump-list{display:flex;overflow-x:auto;scrollbar-width:none;}
.jump-list::-webkit-scrollbar{display:none;}
.jump-list li{flex:0 0 auto;}
.jump-list a{
  display:flex;align-items:center;min-height:48px;padding:0 16px;
  color:var(--ink);font-size:15px;font-weight:700;
  text-decoration:none;white-space:nowrap;
  border-right:2px solid var(--ink);
  transition:background .16s ease,color .16s ease;
}
.jump-list a:hover,.jump-list a:focus-visible{background:var(--ink);color:var(--red);}

/* ── 主体栏 ── */
.cols{
  display:grid;
  grid-template-columns:minmax(0,1fr) 300px;
  gap:44px;
  max-width:1180px;
  margin:0 auto;
  padding:56px 20px 72px;
}
.cols > *{grid-column:1;min-width:0;}
.cols > .rail{grid-column:2;}

.cols > section{
  padding:34px 0;
  border-top:3px solid var(--ink);
}
.cols > section:first-child{border-top:0;padding-top:0;}
.cols > section > small{
  display:block;margin-bottom:8px;
  color:var(--red);font-size:13px;font-weight:700;letter-spacing:.22em;
}
.cols > section h2{
  font-size:clamp(24px,3.4vw,34px);line-height:1.2;
  margin:0 0 16px;
}
.cols > section h3{font-size:22px;line-height:1.3;margin:26px 0 10px;}
.cols > section h4{font-size:19px;margin:22px 0 8px;}
.cols > section p{max-width:68ch;}
.cols > section ul,.cols > section ol{
  list-style:disc;padding-left:24px;margin:0 0 18px;
}
.cols > section ol{list-style:decimal;}
.cols > section li{margin-bottom:10px;}
.cols > section a{
  text-decoration:underline;text-decoration-color:var(--red);
  text-decoration-thickness:2px;text-underline-offset:3px;
}
.cols > section a:hover{color:var(--red);}
.cols > section blockquote{
  margin:0 0 20px;padding:14px 18px;
  background:#fff;border-left:6px solid var(--red);
  border-radius:0 10px 10px 0;
}
.cols > section figure{margin:0 0 20px;}
.cols > section figcaption{font-size:14px;margin-top:8px;opacity:.75;}
.cols > section img{
  border:var(--edge);border-radius:10px;max-width:100%;height:auto;
}
.cols > section table{
  width:100%;border-collapse:collapse;margin:0 0 20px;font-size:16px;
}
.cols > section th,.cols > section td{
  border:var(--edge);padding:10px;text-align:left;vertical-align:top;
}
.cols > section th{background:var(--ink);color:var(--paper);}
.cols > section strong{font-weight:700;}
.cols > section code{
  background:#fff;border:1px solid var(--ink);border-radius:3px;
  padding:1px 5px;font-size:15px;
}
.cols > section hr{
  border:0;border-top:3px solid var(--ink);margin:28px 0;
}

/* 进入动画 */
.cols.stagger > section{
  opacity:0;transform:translateY(20px);
  transition:opacity .38s ease,transform .38s ease;
}
.cols.stagger > section.in{opacity:1;transform:none;}

/* ── 侧栏 ── */
.rail{
  position:sticky;top:calc(var(--hdr) + 68px);
  align-self:start;
  grid-row:1 / -1;
  padding:18px;
  background:var(--paper);
  border:var(--edge);border-radius:10px;
}
.rail small{
  display:block;color:var(--red);font-size:13px;font-weight:700;letter-spacing:.22em;
}
.rail h2{font-size:20px;line-height:1.3;margin:4px 0 12px;}
.rail-list li{border-top:1px solid #CFC9BC;}
.rail-list li:first-child{border-top:0;}
.rail-list a{
  display:flex;align-items:center;min-height:40px;padding:6px 0;
  font-size:15px;text-decoration:none;
  transition:color .16s ease;
}
.rail-list a:hover,.rail-list a:focus-visible{color:var(--red);}
.totop{
  display:flex;align-items:center;justify-content:center;
  min-height:42px;margin-top:16px;padding:0 12px;
  background:var(--red);color:var(--ink);
  border-radius:10px;font-size:15px;font-weight:700;text-decoration:none;
  transition:background .16s ease,color .16s ease;
}
.totop:hover,.totop:focus-visible{background:var(--ink);color:var(--red);}

/* ── 页脚 ── */
footer{
  display:flex;flex-wrap:wrap;justify-content:space-between;
  gap:16px 32px;
  padding:26px 20px 36px;
  background:var(--ink);color:var(--paper);
  border-top:4px solid var(--red);
}
footer > section{flex:1 1 260px;min-width:0;}
.copy{margin:0;font-size:15px;line-height:2.8;}
.foot-links ol{display:flex;flex-wrap:wrap;gap:2px 16px;justify-content:flex-end;}
.foot-links a{
  display:inline-flex;align-items:center;min-height:40px;padding:0 4px;
  color:var(--paper);font-size:15px;text-decoration:none;
  transition:color .16s ease;
}
.foot-links a:hover,.foot-links a:focus-visible{color:var(--red);}

/* ── 断点 ── */
@media (max-width:900px){
  .cols{
    grid-template-columns:1fr;
    gap:0;
    padding:40px 18px 56px;
  }
  .cols > .rail{
    grid-column:1;grid-row:auto;
    position:static;margin-top:34px;
  }
  .cols > section{padding:26px 0;}
  .hero{padding:20px 18px 96px;}
  .hero-copy p{font-size:15px;}
  .foot-links ol{justify-content:flex-start;}
}

@media (max-width:420px){
  .contact{display:none;}
  .hero-copy h1{font-size:clamp(28px,8.4vw,40px);}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto;}
  .cols.stagger > section{opacity:1;transform:none;transition:none;}
  .hero-art img{transition:none;}
  .drawer{transition:none;}
}

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