@import url('https://fonts.googleapis.com/css2?family=Fredoka:wght@400;500;600;700&family=Nunito:wght@300;400;500;600;700&display=swap');
*,*::before,*::after{box-sizing:border-box}
:root{
  --ink:#000000;
  --paper:#ffffff;
  --mute:#6b6b6b;
  --hair:#d9d9d9;
  --r:4px;
  --gutter:clamp(16px,5vw,72px);
  --sans:"Nunito","Fredoka",system-ui,-apple-system,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  --round:"Fredoka","Nunito",system-ui,sans-serif;
}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
  margin:0;
  overflow-x:hidden;
  background:var(--paper);
  color:var(--ink);
  font-family:var(--sans);
  font-size:17px;
  line-height:1.7;
  font-weight:400;
}
a{color:inherit}
img{max-width:100%}
p{margin:0 0 1.1em}
::selection{background:var(--ink);color:var(--paper)}
:focus-visible{outline:3px solid var(--ink);outline-offset:3px}

/* 顶部停靠条 */
.dock{position:sticky;top:0;z-index:50;background:var(--paper);border-bottom:2px solid var(--ink)}
.bar{display:flex;align-items:center;gap:10px;padding:8px var(--gutter)}
.brand{
  flex:0 0 auto;
  max-width:52%;
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:8px 0;
  font-family:var(--round);
  font-weight:700;
  font-size:1.02rem;
  line-height:1.2;
  letter-spacing:-.02em;
  text-decoration:none;
}
.drawer{position:relative;margin-left:auto}
.drawer > summary{
  list-style:none;
  cursor:pointer;
  user-select:none;
  display:inline-flex;
  align-items:center;
  gap:10px;
  min-height:44px;
  padding:10px 16px;
  border:2px solid var(--ink);
  border-radius:var(--r);
  font-weight:700;
  font-size:1rem;
  letter-spacing:.04em;
  transition:background .18s ease,color .18s ease;
}
.drawer > summary::-webkit-details-marker{display:none}
.drawer > summary::after{
  content:"";
  width:9px;height:9px;
  border-right:2px solid currentColor;
  border-bottom:2px solid currentColor;
  transform:rotate(45deg) translateY(-2px);
  transition:transform .2s ease;
}
.drawer[open] > summary{background:var(--ink);color:var(--paper)}
.drawer[open] > summary::after{transform:rotate(-135deg) translateY(-2px)}
.drawer menu{
  list-style:none;
  margin:10px 0 0;
  padding:6px;
  position:absolute;
  right:0;
  top:100%;
  z-index:60;
  width:min(80vw,320px);
  max-height:70vh;
  overflow:auto;
  background:var(--paper);
  border:2px solid var(--ink);
  border-radius:var(--r);
}
.drawer menu a{
  display:flex;
  align-items:center;
  min-height:44px;
  padding:10px 12px;
  border-radius:var(--r);
  text-decoration:none;
  font-weight:600;
  line-height:1.35;
  transition:background .15s ease,color .15s ease,padding-left .15s ease;
}
.drawer menu a:hover,
.drawer menu a:focus-visible{background:var(--ink);color:var(--paper);padding-left:18px}
.cta{
  flex:0 0 auto;
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:10px 18px;
  background:var(--ink);
  color:var(--paper);
  border-radius:var(--r);
  text-decoration:none;
  font-weight:700;
  letter-spacing:.04em;
  transition:transform .18s ease;
}
.cta:hover{transform:translateY(-2px)}

/* 二级锚点条 */
.rail{display:flex;overflow-x:auto;border-top:1px solid var(--hair);scrollbar-width:none}
.rail::-webkit-scrollbar{display:none}
.rail a{
  flex:0 0 auto;
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:0 15px;
  font-size:1rem;
  font-weight:600;
  white-space:nowrap;
  text-decoration:none;
  border-right:1px solid var(--hair);
  transition:background .15s ease,color .15s ease;
}
.rail a:hover,.rail a:focus-visible{background:var(--ink);color:var(--paper)}

/* 大字头图 */
.hero{
  position:relative;
  overflow:hidden;
  min-height:70vh;
  display:flex;
  align-items:flex-end;
  justify-content:flex-end;
  padding:clamp(28px,7vw,96px) var(--gutter) clamp(64px,12vw,150px);
  background:var(--ink);
  color:var(--paper);
  clip-path:polygon(0 0,100% 0,100% 100%,0 calc(100% - 68px));
}
.hero-img{
  position:absolute;
  inset:0;
  width:100%;
  height:100%;
  object-fit:cover;
  filter:grayscale(1) contrast(1.15);
  opacity:.5;
}
.hero-in{position:relative;text-align:right;max-width:1120px}
.hero-in h1{
  margin:0;
  font-family:var(--round);
  font-weight:700;
  font-size:clamp(3rem,10vw,12rem);
  line-height:.92;
  letter-spacing:-.05em;
  word-break:break-word;
}
.lede{
  margin:clamp(16px,3vw,32px) 0 0 auto;
  max-width:36ch;
  font-size:1.05rem;
  line-height:1.65;
  color:var(--paper);
  opacity:.86;
}

/* 正文栅格 */
.wrap{
  display:grid;
  grid-template-columns:minmax(0,1fr) 262px;
  gap:clamp(24px,4vw,68px);
  max-width:1260px;
  margin:0 auto;
  padding:0 var(--gutter);
}
.stage{min-width:0;padding-top:clamp(32px,6vw,80px)}
div[id]{scroll-margin-top:132px}

section :is(h2,h3,h4){
  margin:0 0 .38em;
  font-family:var(--round);
  font-weight:700;
  letter-spacing:-.04em;
  line-height:1.08;
}
section h2{font-size:clamp(1.9rem,5.6vw,3.4rem)}
section h3{font-size:clamp(1.32rem,3.4vw,1.95rem)}
section h4{font-size:1.15rem;letter-spacing:-.01em}
hr{
  border:0;
  border-top:2px solid var(--ink);
  margin:0 0 clamp(20px,3vw,40px);
}
section p,section ul,section ol,section blockquote,section figure{margin:0 0 1.15em}
section ul,section ol{padding-left:1.25em}
section li{margin:0 0 .5em}
section a{text-decoration:underline;text-underline-offset:3px;text-decoration-thickness:2px}
section a:hover{background:var(--ink);color:var(--paper);text-decoration:none}
section strong{font-weight:700}
section blockquote{
  border-left:6px solid var(--ink);
  padding:6px 0 6px 20px;
  font-size:1.1rem;
  line-height:1.6;
}
section figure{margin-left:0;margin-right:0}
section img{border-radius:var(--r);height:auto}
section figcaption{font-size:.95rem;color:var(--mute);margin-top:8px}
section > div{
  padding:clamp(36px,7vw,104px) 0;
  border-bottom:2px solid var(--ink);
}
section > div:last-child{border-bottom:0;padding-bottom:0}
section table{width:100%;border-collapse:collapse;margin:0 0 1.2em;font-size:1rem}
section th,section td{border-bottom:1px solid var(--hair);padding:10px 12px;text-align:left}

/* 右侧目录 */
.side{
  align-self:start;
  position:sticky;
  top:132px;
  padding-top:clamp(32px,6vw,80px);
}
.side h2{
  font-family:var(--sans);
  font-size:1rem;
  font-weight:700;
  letter-spacing:.16em;
  margin:0 0 12px;
}
.side hr{margin:0 0 14px;border-top:2px solid var(--ink)}
.toc{list-style:none;margin:0;padding:0}
.toc li{border-bottom:1px solid var(--hair)}
.toc a{
  display:flex;
  align-items:center;
  gap:10px;
  min-height:44px;
  padding:8px 0;
  text-decoration:none;
  font-weight:600;
  line-height:1.35;
  transition:background .15s ease,color .15s ease,padding-left .15s ease;
}
.toc .num{
  font-family:var(--round);
  font-size:.82rem;
  letter-spacing:.06em;
  color:var(--mute);
  min-width:1.7em;
}
.toc a:hover,.toc a:focus-visible{background:var(--ink);color:var(--paper);padding-left:8px}
.toc a:hover .num,.toc a:focus-visible .num{color:var(--paper)}

/* 页脚 */
.foot{
  margin-top:clamp(48px,10vw,130px);
  border-top:2px solid var(--ink);
  padding:clamp(32px,6vw,76px) var(--gutter) 22px;
}
.sign .huge{
  margin:0;
  font-family:var(--round);
  font-weight:700;
  font-size:clamp(2.3rem,12.5vw,8.5rem);
  line-height:.9;
  letter-spacing:-.06em;
  word-break:break-word;
}
.colophon{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:12px 18px;
  margin-top:clamp(20px,3vw,36px);
  padding-top:16px;
  border-top:2px solid var(--ink);
  font-size:1rem;
}
.copy{margin:0}
.foot-links{display:flex;flex-wrap:wrap;gap:4px 16px}
.foot-links a,.top{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:6px 0;
  text-decoration:none;
  font-weight:600;
  border-bottom:2px solid transparent;
  transition:border-color .18s ease;
}
.foot-links a:hover,.top:hover{border-color:var(--ink)}
.top{margin-left:auto;font-weight:700}

/* 滚动显现 */
.reveal{opacity:0;transform:translateY(22px);transition:opacity .7s ease,transform .7s ease}
.reveal.in{opacity:1;transform:none}

@media (max-width:960px){
  .wrap{grid-template-columns:minmax(0,1fr)}
  .side{position:static;padding-top:0;margin-top:clamp(32px,6vw,64px);border-top:2px solid var(--ink);padding-top:20px}
  .stage{padding-top:clamp(28px,5vw,56px)}
}
@media (max-width:640px){
  .cta{display:none}
  .brand{font-size:.98rem}
  .hero{min-height:62vh;padding-bottom:clamp(72px,16vw,110px)}
  .hero-in h1{letter-spacing:-.04em}
  .lede{font-size:1rem}
  .colophon{font-size:.98rem}
  .top{margin-left:0}
}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal{opacity:1;transform:none;transition:none}
  .cta:hover{transform:none}
}

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