:root{
  --ink:#000000;
  --paper:#ffffff;
  --line:rgba(0,0,0,.16);
  --soft:rgba(0,0,0,.58);
  --grid:rgba(0,0,0,.07);
  color-scheme:light;
}
*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:'Source Sans 3','Lexend',system-ui,-apple-system,'Segoe UI','PingFang SC','Hiragino Sans GB','Microsoft YaHei',sans-serif;
  font-size:1.0625rem;
  line-height:1.75;
  font-weight:400;
  letter-spacing:.005em;
  -webkit-font-smoothing:antialiased;
}
h1,h2,h3,h4{
  font-family:'Lexend','Source Sans 3',system-ui,'PingFang SC','Microsoft YaHei',sans-serif;
}
img{max-width:100%;display:block}
a{color:inherit}
hr{border:0;border-top:1px solid var(--ink);margin:1rem 0}
::selection{background:var(--ink);color:var(--paper)}
:focus-visible{outline:2px solid var(--ink);outline-offset:3px}

/* ---------- 顶部：品牌居中 + 胶囊锚点条 ---------- */
.site-head{
  position:sticky;
  top:0;
  z-index:30;
  background:var(--paper);
  border-bottom:1px solid var(--ink);
}
.brand-row{display:flex;justify-content:center;padding:.55rem 1rem .1rem}
.brand{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:.2rem .8rem;
  font-family:'Lexend',sans-serif;
  font-weight:900;
  font-size:clamp(1.15rem,3.6vw,1.65rem);
  letter-spacing:-.05em;
  text-decoration:none;
}
.brand:hover{letter-spacing:-.02em}
.site-head nav{overflow-x:auto;overscroll-behavior-x:contain;-webkit-overflow-scrolling:touch}
.site-head nav p{
  display:flex;
  gap:.4rem;
  margin:0;
  padding:.25rem 1rem .6rem;
  min-width:max-content;
  justify-content:flex-start;
}
.site-head nav a{
  flex:0 0 auto;
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:.45rem 1rem;
  border:1px solid var(--ink);
  border-radius:999px;
  font-size:1rem;
  font-weight:600;
  text-decoration:none;
  white-space:nowrap;
  transition:background .18s ease,color .18s ease,transform .18s ease;
}
.site-head nav a:hover,
.site-head nav a:focus-visible{background:var(--ink);color:var(--paper);transform:translateY(-1px)}

/* ---------- 主区 ---------- */
.shell{
  display:block;
  max-width:1180px;
  margin:0 auto;
  padding:0 1.25rem 3rem;
}

/* ---------- 首屏 ---------- */
.hero{
  display:grid;
  gap:1.5rem;
  align-content:center;
  min-height:45vh;
  padding:2rem 0 2.5rem;
  border-bottom:1px solid var(--ink);
  background-image:
    linear-gradient(var(--grid) 1px,transparent 1px),
    linear-gradient(90deg,var(--grid) 1px,transparent 1px);
  background-size:46px 46px;
  background-position:center top;
}
.hero h1{
  margin:0;
  font-weight:900;
  font-size:clamp(2.5rem,9vw,5rem);
  line-height:.94;
  letter-spacing:-.055em;
  word-break:break-word;
}
.hero-media:empty{display:none}
.hero-media img{
  width:100%;
  aspect-ratio:4/3;
  object-fit:cover;
  border:1px solid var(--ink);
  border-radius:10px;
  filter:grayscale(1) contrast(1.06);
}

/* ---------- 正文 ---------- */
.prose{min-width:0;padding-top:.5rem}
.prose article{
  padding:3rem 0;
  border-top:1px solid var(--ink);
  scroll-margin-top:150px;
}
.prose article:first-child{border-top:0;padding-top:1.5rem}
.prose h2{
  margin:0 0 .7rem;
  font-weight:900;
  font-size:clamp(1.6rem,4.8vw,2.7rem);
  line-height:1.06;
  letter-spacing:-.045em;
}
.prose h2+hr{margin:.9rem 0 1.8rem;border-top-width:2px}
.prose h3{
  margin:2rem 0 .6rem;
  font-weight:800;
  font-size:clamp(1.2rem,3vw,1.55rem);
  letter-spacing:-.02em;
}
.prose h3+hr{margin:.7rem 0 1.2rem}
.prose p{margin:0 0 1.15rem;max-width:66ch}
.prose p:last-child{margin-bottom:0}
.prose ul,.prose ol{margin:0 0 1.2rem;padding-left:1.3rem;max-width:66ch}
.prose li{margin:.35rem 0}
.prose a{text-underline-offset:3px}
.prose strong{font-weight:700}
.prose blockquote{
  margin:1.8rem 0;
  padding:.9rem 1.3rem;
  border-left:4px solid var(--ink);
  font-size:1.18rem;
  font-weight:600;
  line-height:1.55;
}
.prose figure{margin:1.8rem 0}
.prose figure img{border:1px solid var(--ink);border-radius:10px}
.prose figcaption{font-size:1rem;color:var(--soft);margin-top:.5rem}
.prose table{width:100%;border-collapse:collapse;margin:1.5rem 0;font-size:1rem}
.prose th,.prose td{border:1px solid var(--ink);padding:.6rem .75rem;text-align:left}
.prose th{font-weight:700}

/* ---------- 右侧栏 ---------- */
.rail{
  margin:2rem 0 0;
  padding:1.1rem 1.1rem 1.3rem;
  border:1px solid var(--ink);
  border-radius:10px;
  background:var(--paper);
}
.rail-label{
  margin:0;
  font-size:1rem;
  font-weight:800;
  letter-spacing:.16em;
  line-height:1.4;
}
.rail hr{margin:.55rem 0 .2rem}
.rail ul{list-style:none;margin:0;padding:0}
.rail li+li{border-top:1px solid var(--line)}
.rail a{
  display:flex;
  align-items:center;
  min-height:42px;
  padding:.3rem 0;
  font-size:1rem;
  text-decoration:none;
}
.rail a:hover,.rail a:focus-visible{text-decoration:underline;text-underline-offset:4px}

/* ---------- 页脚 ---------- */
.foot{margin-top:2.5rem;border-top:2px solid var(--ink)}
.foot-cta{
  display:grid;
  gap:1.4rem;
  justify-items:start;
  padding:3rem 1.25rem;
  border-bottom:1px solid var(--ink);
}
.foot-big{
  margin:0;
  font-family:'Lexend',sans-serif;
  font-weight:900;
  font-size:clamp(2.3rem,11vw,6rem);
  line-height:.88;
  letter-spacing:-.06em;
  word-break:break-word;
}
.pill{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:.5rem 1.15rem;
  border:1px solid var(--ink);
  border-radius:999px;
  background:var(--paper);
  color:var(--ink);
  font-size:1rem;
  font-weight:600;
  text-decoration:none;
  transition:transform .18s ease,box-shadow .18s ease,background .18s ease,color .18s ease;
}
.pill:hover,.pill:focus-visible{
  transform:translate(-2px,-2px);
  box-shadow:4px 4px 0 var(--ink);
  background:var(--ink);
  color:var(--paper);
}
.pill-lg{font-weight:800;padding:.6rem 1.4rem}
.foot-two{
  display:grid;
  gap:2.4rem;
  padding:2.5rem 1.25rem;
}
.foot-label{
  margin:0 0 .7rem;
  font-size:1rem;
  font-weight:800;
  letter-spacing:.16em;
}
.foot-brandname{
  margin:0 0 .6rem;
  font-family:'Lexend',sans-serif;
  font-weight:800;
  font-size:1.35rem;
  letter-spacing:-.03em;
}
.foot-desc{margin:0;max-width:44ch;font-size:1rem;color:var(--soft)}
.foot-links ul{list-style:none;margin:0;padding:0}
.foot-links a{
  display:flex;
  align-items:center;
  min-height:42px;
  padding:.2rem 0;
  font-size:1rem;
  text-decoration:none;
  border-bottom:1px solid var(--line);
}
.foot-links a:hover,.foot-links a:focus-visible{text-decoration:underline;text-underline-offset:4px}
.foot-base{
  border-top:1px solid var(--ink);
  padding:1.1rem 1.25rem 1.6rem;
}
.foot-base p{margin:0;font-size:1rem;letter-spacing:.02em}

/* ---------- 回到顶部 ---------- */
.to-top{
  position:fixed;
  right:1rem;
  bottom:1rem;
  z-index:40;
  min-height:44px;
  padding:.55rem 1.1rem;
  font:inherit;
  font-weight:700;
  color:var(--ink);
  background:var(--paper);
  border:1px solid var(--ink);
  border-radius:999px;
  box-shadow:4px 4px 0 var(--ink);
  cursor:pointer;
}
.to-top[hidden]{display:none}
.to-top:hover{background:var(--ink);color:var(--paper)}

/* ---------- 宽屏 ---------- */
@media (min-width:700px){
  .site-head nav p{justify-content:center;padding-bottom:.7rem}
  .hero{grid-template-columns:1.3fr .7fr;align-items:center;gap:2.5rem;padding:3rem 0 3.5rem}
  .hero-media img{aspect-ratio:1/1}
  .foot-two{grid-template-columns:1fr 1fr;gap:3rem}
}
@media (min-width:960px){
  .shell{
    display:grid;
    grid-template-columns:minmax(0,1fr) 240px;
    column-gap:3.5rem;
    align-items:start;
    padding:0 2rem 4rem;
  }
  .hero{grid-column:1/-1;padding:4rem 0 4.5rem}
  .rail{position:sticky;top:160px;margin:3rem 0 0;grid-column:2}
  .foot-cta{padding:4.5rem 2rem}
  .foot-two{padding:3rem 2rem}
  .foot-base{padding:1.2rem 2rem 2rem}
  .prose article{padding:4rem 0}
  .prose article:first-child{padding-top:2rem}
}

/* ---------- 动效 ---------- */
@media (prefers-reduced-motion:no-preference){
  .prose article{animation:rise .55s cubic-bezier(.2,.7,.2,1) both}
  .prose article:nth-child(1){animation-delay:.04s}
  .prose article:nth-child(2){animation-delay:.1s}
  .prose article:nth-child(3){animation-delay:.16s}
  .prose article:nth-child(4){animation-delay:.22s}
  .prose article:nth-child(5){animation-delay:.28s}
  .prose article:nth-child(6){animation-delay:.34s}
  .prose article:nth-child(7){animation-delay:.4s}
  .prose article:nth-child(n+8){animation-delay:.46s}
}
@keyframes rise{
  from{opacity:0;transform:translateY(16px)}
  to{opacity:1;transform:none}
}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *{animation:none!important;transition:none!important}
  .pill:hover,.pill:focus-visible{transform:none;box-shadow:4px 4px 0 var(--ink)}
}

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