:root{
  --ink:#000000;
  --blue:#3bb1ff;
  --red:#ff5252;
  --paper:#f4f1e8;
  --paper2:#fffdf6;
  --line:3px solid #000000;
  --serif:"Playfair Display",Georgia,"Songti SC",serif;
  --body:"Source Serif 4",Georgia,"Songti SC",serif;
  --mono:"JetBrains Mono",ui-monospace,monospace;
}

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

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

body{
  margin:0;
  padding-bottom:100px;
  font-family:var(--body);
  font-size:18px;
  line-height:1.72;
  color:var(--ink);
  background-color:var(--paper);
  background-image:
    linear-gradient(rgba(0,0,0,.07) 1px,transparent 1px),
    linear-gradient(90deg,rgba(0,0,0,.07) 1px,transparent 1px);
  background-size:28px 28px;
  overflow-x:hidden;
}

img{max-width:100%}

a{color:inherit}

h1,h2,h3{font-family:var(--serif);color:var(--ink)}

/* 品牌角标 */
.brand{
  position:fixed;
  top:16px;
  left:16px;
  z-index:80;
}

.brand__link{
  display:grid;
  place-items:center;
  width:52px;
  height:52px;
  background:var(--blue);
  border:var(--line);
  box-shadow:4px 4px 0 #000;
  text-decoration:none;
  transition:transform .14s ease,box-shadow .14s ease;
}

.brand__link:hover,
.brand__link:focus-visible{
  transform:translate(-2px,-2px);
  box-shadow:7px 7px 0 #000;
}

.brand__img{display:block;width:44px;height:44px;object-fit:cover}

.brand__mark{
  font-family:var(--serif);
  font-weight:900;
  font-size:26px;
  line-height:1;
}

/* 首屏 */
.hero{
  position:relative;
  min-height:100svh;
  display:grid;
  place-items:center;
  padding:112px 20px 64px;
  background:var(--blue);
  border-bottom:4px solid #000;
  overflow:hidden;
}

.hero::before{
  content:"";
  position:absolute;
  inset:0;
  background-image:radial-gradient(#000 1.4px,transparent 1.6px);
  background-size:20px 20px;
  opacity:.2;
  pointer-events:none;
}

.hero__inner{
  position:relative;
  z-index:1;
  width:100%;
  max-width:900px;
  display:grid;
  justify-items:center;
  gap:24px;
  text-align:center;
}

.hero__title{
  margin:0;
  padding:16px 20px;
  font-size:clamp(2.3rem,8.6vw,5rem);
  font-weight:900;
  line-height:1.04;
  letter-spacing:-.02em;
  background:var(--paper2);
  border:4px solid #000;
  box-shadow:9px 9px 0 #000;
}

.hero__desc{
  margin:0;
  max-width:44ch;
  padding:12px 16px;
  font-size:1.03rem;
  line-height:1.6;
  background:var(--paper2);
  border:3px solid #000;
  box-shadow:5px 5px 0 #000;
}

.hero__media{
  width:100%;
  max-width:840px;
}

.hero__img{
  display:block;
  width:100%;
  height:auto;
  border:4px solid #000;
  box-shadow:9px 9px 0 #000;
  background:var(--red);
  will-change:transform;
}

/* 主体 */
main{padding:56px 16px 40px}

.wrap{
  max-width:1160px;
  margin:0 auto;
  display:grid;
  grid-template-columns:236px minmax(0,1fr);
  gap:26px;
  align-items:start;
}

/* 左栏 */
.rail{
  background:var(--paper2);
  border:var(--line);
  box-shadow:5px 5px 0 #000;
  padding:16px 14px;
  position:sticky;
  top:20px;
}

.rail__h{
  margin:0 0 10px;
  font-family:var(--mono);
  font-size:.82rem;
  font-weight:500;
  letter-spacing:.16em;
}

.rail__h > span{
  display:inline-flex;
  align-items:center;
  gap:8px;
}

.rail__mark{
  width:11px;
  height:11px;
  background:var(--red);
  border:2px solid #000;
}

.rail__list{
  list-style:none;
  margin:0 0 18px;
  padding:0;
  display:grid;
  gap:3px;
}

.rail__list li{animation:rise .5s both;animation-delay:calc(var(--i,0) * 45ms)}

.rail__list a{
  display:flex;
  align-items:center;
  min-height:40px;
  padding:7px 9px;
  font-size:1rem;
  line-height:1.35;
  text-decoration:none;
  border-left:3px solid #000;
  background:#fff;
}

.rail__list a:hover,
.rail__list a:focus-visible{
  background:var(--blue);
}

.rail__back{margin:0}

.rail__back a{
  display:flex;
  align-items:center;
  justify-content:center;
  min-height:42px;
  padding:8px 10px;
  font-family:var(--mono);
  font-size:.85rem;
  letter-spacing:.1em;
  text-decoration:none;
  background:var(--ink);
  color:#fff;
  border:3px solid #000;
  box-shadow:4px 4px 0 var(--red);
}

/* 正文 */
.doc{min-width:0}

.prose{
  background:var(--paper2);
  border:4px solid #000;
  box-shadow:8px 8px 0 #000;
  padding:clamp(18px,4.2vw,44px);
  font-size:1.02rem;
  overflow-wrap:break-word;
}

.prose > *:first-child{margin-top:0}

.prose article + article{
  margin-top:2.4em;
  padding-top:1.5em;
  border-top:3px dashed #000;
}

.prose article{scroll-margin-top:26px}

.prose h2{
  margin:1.9em 0 .65em;
  padding-left:14px;
  font-size:clamp(1.42rem,4.2vw,2.1rem);
  font-weight:900;
  line-height:1.16;
  border-left:10px solid var(--red);
}

.prose h2 > span{display:inline-block}

.prose h3{
  margin:1.6em 0 .5em;
  font-size:1.22rem;
  font-weight:700;
  line-height:1.3;
}

.prose h3 > span{display:inline-block}

.prose p{margin:0 0 1.1em}

.prose ul,.prose ol{
  margin:0 0 1.15em;
  padding-left:1.5em;
}

.prose li{margin:.35em 0}

.prose a{
  color:#000;
  text-decoration:underline;
  text-decoration-thickness:2px;
  text-underline-offset:3px;
}

.prose a:hover{background:var(--blue)}

.prose blockquote{
  margin:1.3em 0;
  padding:12px 16px;
  background:#e8f6ff;
  border:3px solid #000;
  box-shadow:5px 5px 0 #000;
}

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

.prose img{
  display:block;
  width:auto;
  max-width:100%;
  height:auto;
  margin:1.3em 0;
  border:3px solid #000;
  box-shadow:5px 5px 0 #000;
}

.prose table{
  width:100%;
  margin:1.3em 0;
  border-collapse:collapse;
  font-size:.96rem;
}

.prose th,.prose td{
  padding:8px 10px;
  border:2px solid #000;
  text-align:left;
  vertical-align:top;
}

.prose th{background:var(--blue);font-weight:700}

.prose code,.prose pre{font-family:var(--mono);font-size:.9em}

.prose code{
  padding:1px 5px;
  background:#f0ece0;
  border:2px solid #000;
}

.prose pre{
  margin:1.3em 0;
  padding:12px 14px;
  overflow-x:auto;
  background:#f0ece0;
  border:3px solid #000;
}

.prose pre code{padding:0;border:0;background:none}

.prose hr{
  margin:2em 0;
  height:0;
  border:0;
  border-top:3px solid #000;
}

/* 页脚 */
.foot{
  max-width:1160px;
  margin:0 auto;
  padding:8px 16px 46px;
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:12px 18px;
  justify-content:space-between;
}

.foot__form{
  margin:0;
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:10px;
  padding:10px 12px;
  background:var(--paper2);
  border:var(--line);
  box-shadow:5px 5px 0 #000;
}

.foot__label{
  font-family:var(--mono);
  font-size:.84rem;
  letter-spacing:.14em;
}

.foot__input{
  flex:1 1 160px;
  min-width:0;
  min-height:44px;
  padding:8px 10px;
  font-family:var(--body);
  font-size:1rem;
  background:#fff;
  border:3px solid #000;
}

.foot__btn{
  min-height:44px;
  padding:8px 18px;
  font-family:var(--mono);
  font-size:.9rem;
  font-weight:500;
  letter-spacing:.1em;
  background:var(--red);
  color:#000;
  border:3px solid #000;
  box-shadow:4px 4px 0 #000;
  cursor:pointer;
}

.foot__btn:disabled{cursor:default;background:var(--blue)}

.foot__copy{
  font-family:var(--mono);
  font-size:.8rem;
  letter-spacing:.06em;
}

/* 底部菜单条 */
.dock{
  position:fixed;
  left:0;
  right:0;
  bottom:0;
  z-index:90;
  display:flex;
  justify-content:center;
  padding:10px 16px;
  pointer-events:none;
}

.dock__menu{pointer-events:auto}

.dock__btn{
  display:inline-flex;
  align-items:center;
  gap:10px;
  min-height:52px;
  padding:0 22px;
  background:var(--ink);
  color:#fff;
  border:3px solid #000;
  box-shadow:0 -4px 0 var(--red), 5px 5px 0 #000;
  cursor:pointer;
  list-style:none;
  position:relative;
  z-index:3;
  font-family:var(--mono);
  font-size:.9rem;
  letter-spacing:.14em;
}

.dock__btn::-webkit-details-marker{display:none}

.dock__ico{
  display:block;
  width:22px;
  height:3px;
  background:#fff;
  position:relative;
}

.dock__ico::before,
.dock__ico::after{
  content:"";
  position:absolute;
  left:0;
  width:22px;
  height:3px;
  background:#fff;
}

.dock__ico::before{top:-7px}
.dock__ico::after{top:7px}

.dock__txt-b{display:none}
.dock__menu[open] .dock__txt-a{display:none}
.dock__menu[open] .dock__txt-b{display:inline}

.dock__panel{
  position:fixed;
  inset:0;
  z-index:2;
  margin:0;
  padding:104px 20px 44px;
  list-style:none;
  display:grid;
  align-content:start;
  gap:10px;
  overflow-y:auto;
  background:var(--ink);
  background-image:
    linear-gradient(rgba(255,255,255,.09) 1px,transparent 1px),
    linear-gradient(90deg,rgba(255,255,255,.09) 1px,transparent 1px);
  background-size:30px 30px;
  color:#fff;
}

.dock__menu:not([open]) .dock__panel{display:none}

.dock__panel li{animation:rise .34s both;animation-delay:calc(var(--i,0) * 40ms)}

.dock__panel a{
  display:flex;
  align-items:center;
  min-height:56px;
  padding:10px 16px;
  font-family:var(--serif);
  font-weight:900;
  font-size:clamp(1.25rem,5vw,1.9rem);
  line-height:1.2;
  color:#fff;
  text-decoration:none;
  border:3px solid #fff;
}

.dock__panel a:hover,
.dock__panel a:focus-visible{
  background:var(--blue);
  color:#000;
  border-color:#000;
}

@keyframes rise{
  from{opacity:0;transform:translateY(14px)}
  to{opacity:1;transform:none}
}

@media (min-height:660px){
  .dock__panel{align-content:center}
}

/* 断点 */
@media (max-width:880px){
  .wrap{grid-template-columns:1fr;gap:22px}

  .rail{position:static}

  .rail__list{
    grid-template-columns:repeat(2,minmax(0,1fr));
    gap:6px;
  }

  .rail__list a{min-height:44px}
}

@media (max-width:520px){
  body{font-size:17px}

  .hero{padding:96px 16px 52px}

  .prose{box-shadow:6px 6px 0 #000;border-width:3px}

  .foot{justify-content:flex-start;padding-bottom:36px}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}

  *,
  *::before,
  *::after{
    animation-duration:.001ms !important;
    animation-delay:0ms !important;
    transition-duration:.001ms !important;
  }
}

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