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

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

:root{
  --ink:#000;
  --paper:#fff;
  --mute:#5a5a5a;
  --soft:#8a8a8a;
  --hair:#dedede;
  --u:8px;
  --pad:clamp(16px,4vw,44px);
  --max:1240px;
  --sans:"Nunito Sans","Helvetica Neue",Helvetica,Arial,"Hiragino Sans","Noto Sans JP","Microsoft YaHei",sans-serif;
  --round:"Varela Round","Nunito Sans","Helvetica Neue",Helvetica,Arial,sans-serif;
}

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

body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:var(--sans);
  font-size:17px;
  line-height:1.7;
  font-weight:400;
  letter-spacing:.01em;
}

a{color:inherit}
a:focus-visible,button:focus-visible{outline:3px solid currentColor;outline-offset:3px}
img{max-width:100%}

/* ---------- 顶部 ---------- */
.masthead{
  position:sticky;
  top:0;
  z-index:60;
  background:var(--paper);
  border-bottom:2px solid var(--ink);
}

.strip{
  background:var(--ink);
  color:var(--paper);
  padding:6px var(--pad);
}
.strip-txt{
  margin:0;
  font-size:16px;
  line-height:1.5;
  letter-spacing:.05em;
  white-space:nowrap;
  overflow:hidden;
  text-overflow:ellipsis;
}

.bar{
  display:flex;
  align-items:center;
  gap:var(--u);
  max-width:var(--max);
  margin:0 auto;
  padding:0 var(--pad);
  min-height:68px;
}

.nav{display:flex;flex:1 1 0;gap:2px;flex-wrap:wrap}
.nav-r{justify-content:flex-end}
.nav-l{justify-content:flex-start}

.nav-link{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:8px 10px;
  font-size:16px;
  line-height:1.3;
  text-decoration:none;
  border-bottom:2px solid transparent;
  transition:border-color .18s ease,background .18s ease;
}
.nav-link:hover{border-bottom-color:var(--ink);background:rgba(0,0,0,.05)}

.brand{
  display:inline-flex;
  align-items:center;
  gap:6px;
  min-height:44px;
  padding:6px 14px;
  font-family:var(--round);
  font-size:20px;
  letter-spacing:.08em;
  text-decoration:none;
  white-space:nowrap;
}
.brand-mark{font-size:20px;line-height:1}

.burger{
  display:none;
  align-items:center;
  min-height:44px;
  padding:8px 16px;
  font:inherit;
  font-size:16px;
  background:var(--ink);
  color:var(--paper);
  border:0;
  cursor:pointer;
}

/* ---------- 首屏 ---------- */
.hero{
  position:relative;
  min-height:100vh;
  min-height:100svh;
  display:flex;
  align-items:flex-end;
  overflow:hidden;
  background:var(--ink);
  color:var(--paper);
  clip-path:polygon(0 0,100% 0,100% 93%,0 100%);
  padding:calc(var(--u)*16) var(--pad) calc(var(--u)*11);
}

.hero-media{position:absolute;inset:0;z-index:0}
.hero-media img{
  display:block;
  width:100%;
  height:100%;
  object-fit:cover;
  filter:grayscale(1) contrast(1.15);
  opacity:.5;
}

.hero::after{
  content:"";
  position:absolute;
  inset:0;
  z-index:1;
  background-image:radial-gradient(currentColor 1px,transparent 1px);
  background-size:24px 24px;
  opacity:.16;
  pointer-events:none;
  color:var(--paper);
}

.hero-inner{
  position:relative;
  z-index:2;
  width:100%;
  max-width:var(--max);
  margin:0 auto;
}

.hero-h1{
  margin:0 0 20px;
  max-width:15ch;
  font-family:var(--round);
  font-size:clamp(2.1rem,7.2vw,4.6rem);
  line-height:1.1;
  font-weight:400;
  letter-spacing:-.01em;
}

.hero-desc{
  margin:0 0 28px;
  max-width:44ch;
  font-size:18px;
  line-height:1.65;
  color:#ededed;
}

.hero-cta{
  display:inline-flex;
  align-items:center;
  min-height:48px;
  padding:12px 26px;
  font-weight:700;
  letter-spacing:.12em;
  text-decoration:none;
  background:var(--paper);
  color:var(--ink);
  transition:background .2s ease,color .2s ease,box-shadow .2s ease,transform .2s ease;
}
.hero-cta:hover{
  background:var(--ink);
  color:var(--paper);
  box-shadow:inset 0 0 0 2px var(--paper);
  transform:translateY(-2px);
}

/* ---------- 主体网格 ---------- */
.wrap{
  display:grid;
  grid-template-columns:repeat(12,minmax(0,1fr));
  gap:calc(var(--u)*4);
  max-width:var(--max);
  margin:0 auto;
  padding:calc(var(--u)*8) var(--pad) calc(var(--u)*10);
}

.col-main{grid-column:1/span 8;min-width:0}
.col-side{
  grid-column:9/-1;
  align-self:start;
  position:sticky;
  top:150px;
  min-width:0;
}

/* ---------- 正文 ---------- */
.prose{min-width:0}

.prose > article{
  padding-top:calc(var(--u)*6);
  border-top:2px solid var(--ink);
  scroll-margin-top:140px;
}
.prose > article:first-child{border-top:0;padding-top:0}

.prose h2{
  margin:0 0 12px;
  font-family:var(--round);
  font-size:clamp(1.55rem,3.4vw,2.4rem);
  line-height:1.2;
  font-weight:400;
  letter-spacing:-.01em;
  scroll-margin-top:140px;
}
.prose h3{
  margin:32px 0 12px;
  font-family:var(--round);
  font-size:1.3rem;
  line-height:1.35;
  font-weight:400;
}
.prose hr{
  border:0;
  border-top:4px solid var(--ink);
  width:64px;
  margin:0 0 24px;
}
.prose p{margin:0 0 20px;max-width:64ch}
.prose ul,.prose ol{margin:0 0 20px;padding-left:1.5em}
.prose li{margin:0 0 8px}
.prose li::marker{color:var(--soft)}

.prose a{
  text-decoration:underline;
  text-underline-offset:3px;
  text-decoration-thickness:1px;
  transition:text-decoration-thickness .15s ease;
}
.prose a:hover{text-decoration-thickness:3px}

.prose img{
  display:block;
  height:auto;
  margin:24px 0;
  filter:grayscale(1);
}
.prose figure{margin:24px 0}

.prose blockquote{
  margin:24px 0;
  padding:6px 0 6px 20px;
  border-left:6px solid var(--ink);
  font-weight:600;
}

.prose table{width:100%;border-collapse:collapse;margin:24px 0;font-size:16px}
.prose th,.prose td{border-bottom:1px solid var(--ink);padding:10px 8px;text-align:left;vertical-align:top}
.prose th{background:var(--ink);color:var(--paper);font-weight:600}

.prose code,.prose pre{font-size:16px}

/* ---------- 侧栏 ---------- */
.col-side{border-top:4px solid var(--ink);padding-top:16px}
.side-h{
  margin:0 0 10px;
  font-family:var(--round);
  font-size:1.05rem;
  font-weight:400;
  letter-spacing:.14em;
}
.col-side hr{border:0;border-top:1px solid var(--ink);margin:0 0 14px}

.toc{list-style:none;margin:0;padding:0;counter-reset:t}
.toc li{counter-increment:t;border-bottom:1px solid var(--hair)}
.toc a{
  display:flex;
  align-items:center;
  gap:12px;
  min-height:44px;
  padding:8px 0;
  font-size:16px;
  line-height:1.4;
  text-decoration:none;
  transition:background .18s ease,color .18s ease,padding-left .18s ease;
}
.toc a::before{
  content:counter(t,decimal-leading-zero);
  font-size:16px;
  color:var(--soft);
  min-width:2.2ch;
  transition:color .18s ease;
}
.toc a:hover{background:var(--ink);color:var(--paper);padding-left:10px}
.toc a:hover::before{color:var(--paper)}

/* ---------- 页脚 ---------- */
.foot{
  display:flex;
  align-items:center;
  justify-content:space-between;
  flex-wrap:wrap;
  gap:16px 24px;
  border-top:2px solid var(--ink);
  padding:calc(var(--u)*4) var(--pad);
}

.foot-brand a{
  display:inline-flex;
  align-items:center;
  gap:6px;
  min-height:44px;
  font-family:var(--round);
  font-size:19px;
  letter-spacing:.08em;
  text-decoration:none;
}

.foot-nav dl{display:flex;flex-wrap:wrap;align-items:center;gap:0 2px;margin:0}
.foot-nav dt{margin:0}
.foot-nav dt a{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:6px 8px;
  font-size:16px;
  text-decoration:none;
  transition:background .18s ease,color .18s ease;
}
.foot-nav dt a:hover{background:var(--ink);color:var(--paper)}
.foot-nav dd{margin:0 12px 0 2px;font-size:16px;color:var(--soft)}

.foot-copy p{margin:0;font-size:16px;color:var(--mute);letter-spacing:.04em}

/* ---------- 入场 ---------- */
.rv{
  opacity:0;
  transform:translateY(18px);
  transition:opacity .55s cubic-bezier(.2,.7,.2,1),transform .55s cubic-bezier(.2,.7,.2,1);
}
.rv.in{opacity:1;transform:none}

/* ---------- 断点 ---------- */
@media (max-width:900px){
  .bar{flex-wrap:wrap;min-height:0;padding-top:6px;padding-bottom:6px}
  .brand{order:1;flex:1 1 auto;justify-content:flex-start;padding-left:0;font-size:19px}
  .burger{display:inline-flex;order:2}
  .nav{
    display:none;
    order:3;
    flex:1 1 100%;
    flex-direction:column;
    gap:0;
    margin-top:6px;
    padding:6px 0 4px;
    border-top:2px solid var(--ink);
  }
  .nav-r{justify-content:flex-start}
  .masthead.open .nav{display:flex}
  .nav-link{min-height:48px;padding:10px 0;border-bottom:1px solid var(--hair)}
  .nav-link:hover{background:none;border-bottom-color:var(--ink)}
}

@media (max-width:860px){
  .wrap{grid-template-columns:1fr;padding-top:calc(var(--u)*6);gap:calc(var(--u)*6)}
  .col-main,.col-side{grid-column:1/-1}
  .col-side{position:static;top:auto}
  .hero{padding:calc(var(--u)*14) var(--pad) calc(var(--u)*10);clip-path:polygon(0 0,100% 0,100% 96%,0 100%)}
  .hero-desc{font-size:17px}
}

@media (max-width:620px){
  .foot{flex-direction:column;align-items:flex-start;gap:10px}
  .foot-nav dl{flex-direction:row}
  .foot-nav dd{margin-right:10px}
  .prose h2{font-size:1.6rem}
  .hero-h1{max-width:20ch}
}

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

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