@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600&display=swap');

:root{
  --ink:#000;
  --blue:#3bb1ff;
  --red:#ff5252;
  --pop:#ffdb58;
  --paper:#f7f5ef;
  --line:3px solid #000;
  --shadow:6px 6px 0 #000;
}

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

html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
  margin:0;
  font-family:Inter,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,sans-serif;
  font-size:17px;
  line-height:1.68;
  color:var(--ink);
  background:var(--paper);
  overflow-x:hidden;
}
img{max-width:100%;display:block}
a{color:inherit}
p{margin:0 0 1em}
h1,h2,h3{line-height:1.2;letter-spacing:-.02em;margin:0 0 10px}
:focus-visible{outline:3px solid var(--red);outline-offset:2px}

/* ---------- 顶栏 ---------- */
.bar{position:sticky;top:0;z-index:60;background:#fff;border-bottom:var(--line)}
.bar-top{display:flex;align-items:center;padding:9px 16px;border-bottom:var(--line)}
.brand{display:inline-flex;align-items:center;gap:10px;min-height:44px;text-decoration:none;font-weight:800;font-size:1.15rem;letter-spacing:-.01em}
.brand .mark{display:inline-flex;align-items:center;justify-content:center;width:32px;height:32px;background:var(--red);border:var(--line);border-radius:9px;font-size:1rem}
.bar-nav{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:9px 16px;background:var(--paper)}

.dd{position:relative}
.dd>summary{display:inline-flex;align-items:center;gap:9px;min-height:44px;padding:.45rem 1rem;background:#fff;border:var(--line);border-radius:14px;box-shadow:4px 4px 0 #000;font-weight:700;cursor:pointer;list-style:none}
.dd>summary::-webkit-details-marker{display:none}
.dd>summary::after{content:"";width:9px;height:9px;border-right:3px solid #000;border-bottom:3px solid #000;transform:rotate(45deg) translateY(-2px)}
.dd[open]>summary{background:var(--pop)}
.dd menu{position:absolute;left:0;top:calc(100% + 10px);z-index:70;width:min(84vw,330px);margin:0;padding:0;list-style:none;background:#fff;border:var(--line);border-radius:20px;box-shadow:var(--shadow);max-height:70vh;overflow:auto}
.dd menu li+li{border-top:2px solid #000}
.dd menu a{display:flex;align-items:center;min-height:46px;padding:.5rem .9rem;text-decoration:none;font-weight:600}
.dd menu a:hover,.dd menu a:focus-visible{background:var(--blue)}

.cta{display:inline-flex;align-items:center;min-height:44px;padding:.45rem 1.1rem;background:var(--red);border:var(--line);border-radius:14px;box-shadow:4px 4px 0 #000;font-weight:800;text-decoration:none;white-space:nowrap}
.cta:hover{background:var(--pop)}

/* ---------- 首屏 ---------- */
.hero{
  position:relative;
  min-height:100vh;
  min-height:100svh;
  display:flex;
  align-items:center;
  justify-content:center;
  overflow:hidden;
  padding:34px 16px 48px;
  background-color:var(--blue);
  background-image:radial-gradient(rgba(0,0,0,.16) 1.5px,transparent 1.7px);
  background-size:20px 20px;
  border-bottom:var(--line);
}
.hero-img{position:absolute;inset:-10% 0 auto 0;width:100%;height:122%;object-fit:cover;z-index:0;transform:scale(1.06);will-change:transform}
.hero-veil{position:absolute;inset:0;background:rgba(0,0,0,.24);z-index:1}
.hero-inner{position:relative;z-index:2;width:100%;max-width:780px;background:#fff;border:var(--line);border-radius:28px;box-shadow:9px 9px 0 #000;padding:clamp(22px,4vw,44px)}
.hero-inner h1{font-size:clamp(1.75rem,5.6vw,3.1rem);line-height:1.14;margin:0 0 14px}
.hero-lead{font-size:1.02rem;max-width:48ch;margin:0 0 22px}
.hero-btn{display:inline-flex;align-items:center;min-height:48px;padding:.6rem 1.3rem;background:var(--blue);border:var(--line);border-radius:14px;box-shadow:5px 5px 0 #000;font-weight:800;text-decoration:none}
.hero-btn:hover{background:var(--pop)}

/* ---------- 主体 ---------- */
.wrap{max-width:1120px;margin:0 auto;padding:clamp(22px,4vw,46px) 16px}
.body-grid{display:grid;grid-template-columns:1fr;gap:26px;align-items:start}

article{
  order:1;
  min-width:0;
  background:#fff;
  border:var(--line);
  border-radius:28px;
  box-shadow:8px 8px 0 #000;
  padding:clamp(18px,3vw,34px);
}
article div[id]{scroll-margin-top:140px}
article>div+div{border-top:3px dashed var(--ink);margin-top:26px;padding-top:26px}
article h2{font-size:1.42rem;margin:0}
article h3{font-size:1.16rem;margin:0 0 8px}
article p,article li{font-size:1.04rem}
article ul,article ol{padding-left:1.25rem;margin:0 0 1em}
article li{margin-bottom:.45em}
article a{text-decoration:underline;text-decoration-thickness:2px;text-underline-offset:3px}
article a:hover{background:var(--pop)}
article blockquote{margin:0 0 1em;padding:12px 16px;background:var(--paper);border-left:6px solid var(--red);border-radius:0 14px 14px 0}
article strong{font-weight:700}
hr{height:6px;border:0;background:var(--red);width:72px;margin:14px 0 20px}
article h2+hr,aside h2+hr{margin-top:12px}

/* ---------- 侧栏 ---------- */
.side{order:2;background:#fff;border:var(--line);border-radius:28px;box-shadow:6px 6px 0 #000;padding:16px}
.side h2{font-size:1.02rem;margin:0;letter-spacing:.02em}
.side-list{list-style:none;margin:0;padding:0}
.side-list li{margin-bottom:8px}
.side-list li:last-child{margin-bottom:0}
.side-list a{display:flex;align-items:center;min-height:44px;padding:.4rem .7rem;background:var(--paper);border:2px solid #000;border-radius:12px;text-decoration:none;font-weight:600;font-size:.96rem}
.side-list a:hover{background:var(--blue)}

/* ---------- 页脚 ---------- */
.foot{margin-top:44px;background:var(--ink);color:#fff;border-top:var(--line)}
.f-cols{display:grid;grid-template-columns:1fr;gap:22px;max-width:1120px;margin:0 auto;padding:30px 16px}
.f-mark{display:inline-flex;align-items:center;justify-content:center;width:44px;height:44px;margin:0 0 8px;background:var(--red);border:var(--line);border-radius:12px;color:#000;font-weight:800;font-size:1.15rem}
.f-name{margin:0;font-weight:800;font-size:1.1rem}
.foot dl{margin:0}
.foot dt{font-weight:700;font-size:.82rem;letter-spacing:.16em;color:var(--pop);margin-bottom:6px}
.foot dd{margin:0}
.foot dd a{display:flex;align-items:center;min-height:44px;color:#fff;text-decoration:none;border-bottom:2px solid rgba(255,255,255,.22)}
.foot dd a:hover{color:var(--pop);border-bottom-color:var(--pop)}
.f-form{grid-column:1/-1;display:flex;flex-wrap:wrap;gap:10px;align-items:center;margin-top:6px}
.f-form input{flex:1 1 200px;min-height:48px;padding:.5rem .85rem;font:inherit;color:#000;background:#fff;border:var(--line);border-radius:12px}
.f-form button{min-height:48px;padding:.5rem 1.2rem;font:inherit;font-weight:800;color:#000;background:var(--blue);border:var(--line);border-radius:12px;box-shadow:4px 4px 0 var(--red);cursor:pointer}
.f-form button:hover{background:var(--pop)}
.f-copy{max-width:1120px;margin:0 auto;padding:14px 16px 20px;font-size:.9rem;border-top:3px solid #fff}

/* ---------- 动效 ---------- */
.reveal{opacity:0;transform:translateY(16px)}
.reveal.in{opacity:1;transform:none;transition:opacity .5s ease,transform .5s ease}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal{opacity:1;transform:none;transition:none}
  .hero-img{transform:none !important}
}

/* ---------- 断点 ---------- */
@media (min-width:640px){
  .f-cols{grid-template-columns:1fr 1fr}
}
@media (min-width:920px){
  .body-grid{grid-template-columns:250px minmax(0,1fr);gap:30px}
  .side{order:1;position:sticky;top:136px}
  article{order:2}
  .f-cols{grid-template-columns:1.3fr 1fr 1fr 1fr}
  .bar-top{padding:10px 24px}
  .bar-nav{padding:10px 24px}
  .wrap{padding:46px 24px}
  .f-cols{padding:34px 24px}
  .f-copy{padding:16px 24px 22px}
}
@media (min-width:1100px){
  .hero-inner{padding:48px}
}

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