*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:root{
  --ink:#1e1b4b;--muted:#575569;--line:#e4e4e7;
  --indigo:#4338ca;--indigo-deep:#3730a3;--indigo-soft:#eef2ff;
  --copper:#c2410c;--copper-soft:#fff7ed;
  --header-h:58px;--content:880px;--fold:28px;
}
html{scroll-behavior:smooth}
body{font-family:"Noto Sans SC",system-ui,sans-serif;color:var(--ink);background:#fff;line-height:1.8;font-size:16px}
img{max-width:100%;height:auto;display:block}
a{color:var(--indigo-deep);text-decoration:none}
a:hover{text-decoration:underline}

.site-header{position:sticky;top:0;z-index:350;background:#fff;border-bottom:3px solid var(--indigo)}
.header-inner{max-width:1000px;margin:0 auto;padding:0 1.15rem;display:flex;align-items:center;justify-content:space-between;min-height:var(--header-h)}
.brand{display:flex;align-items:center;gap:.75rem;color:var(--ink);font-size:.91rem;text-decoration:none}
.brand:hover{text-decoration:none}
.brand em{font-style:normal;font-weight:700;color:var(--indigo)}
.brand span{line-height:1.34;max-width:380px}

.nav-toggle{display:none;background:none;border:none;cursor:pointer;padding:.5rem;flex-direction:column;gap:5px}
.nav-toggle span{display:block;width:22px;height:2px;background:var(--ink);transition:transform .2s}
.nav-toggle.is-open span:nth-child(1){transform:translateY(7px) rotate(45deg)}
.nav-toggle.is-open span:nth-child(2){opacity:0}
.nav-toggle.is-open span:nth-child(3){transform:translateY(-7px) rotate(-45deg)}

.site-nav ul{display:flex;gap:1rem;list-style:none}
.site-nav a{color:var(--muted);font-size:.88rem;text-decoration:none}
.site-nav a:hover,.site-nav a.active{color:var(--indigo);font-weight:600}

.ads-top-bar{background:var(--indigo-soft);border-bottom:1px solid var(--line);padding:.55rem 0}
#applist{display:flex;align-items:center;gap:1rem;flex-wrap:wrap}
.applist-title{font-size:.78rem;color:var(--muted);white-space:nowrap}
#ads{display:flex;gap:.75rem;flex-wrap:wrap}
.ads-item figure{margin:0;text-align:center}
.ads-item img{border-radius:8px}
.ads-item .caption{font-size:.68rem;color:var(--muted);margin-top:.2rem;max-width:65px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}

.page-wrap{max-width:var(--content);margin:0 auto;padding:2.1rem 1.3rem 4rem}

.hero-band{
  background:linear-gradient(160deg,var(--indigo-soft) 0%,#fff 42%,var(--copper-soft) 100%);
  border:1px solid var(--line);border-radius:20px 20px 20px 4px;
  padding:2.1rem 2rem 1.85rem;margin-bottom:2.4rem;position:relative;overflow:hidden;
}
.hero-band::after{
  content:"";position:absolute;bottom:-40px;right:-40px;width:160px;height:160px;
  background:radial-gradient(circle,rgba(67,56,202,.1) 0%,transparent 68%);pointer-events:none;
}
.hero-tag{display:inline-block;font-size:.76rem;font-weight:600;color:var(--copper);background:#fff;border:1px solid var(--copper);padding:.24rem .82rem;border-radius:999px;margin-bottom:.9rem}
.hero-band h1{font-size:1.52rem;line-height:1.37;font-weight:700;margin-bottom:.88rem;color:var(--ink);max-width:700px}
.hero-lead{font-size:1rem;color:var(--muted);margin-bottom:.68rem;text-align:justify;max-width:720px}
.hero-chips{display:flex;flex-wrap:wrap;gap:.5rem;margin-top:1.15rem}
.hero-chips span{font-size:.75rem;background:#fff;border:1px solid var(--indigo);color:var(--indigo);padding:.24rem .72rem;border-radius:8px}

.section-jump{
  display:flex;flex-wrap:wrap;gap:.48rem;margin-bottom:1.75rem;
  padding:.85rem 1rem;background:var(--indigo-soft);border-radius:12px;border:1px solid var(--line);
}
.section-jump a{font-size:.8rem;color:var(--muted);background:#fff;padding:.34rem .78rem;border-radius:8px;border:1px solid var(--line)}
.section-jump a:hover{color:var(--indigo);text-decoration:none;border-color:var(--indigo)}

.stack-zone{position:relative;padding:.5rem 0 2.5rem;perspective:1200px}
.stack-card{
  position:relative;background:#fff;border:1px solid var(--line);border-radius:14px;
  padding:1.7rem 1.8rem 1.6rem;margin-bottom:-2.1rem;
  box-shadow:0 10px 32px rgba(30,27,75,.07);
  transform:rotateX(calc(var(--rx,0) * 1deg)) rotateZ(var(--rz,0deg)) translateY(var(--ty,0));
  transition:transform .3s ease,box-shadow .3s ease,border-color .25s,opacity .25s;
  z-index:var(--z,1);cursor:pointer;opacity:calc(1 - var(--fade,0));
}
.stack-card:last-child{margin-bottom:0}
.stack-card:nth-child(odd){--rz:.42deg;border-top:3px solid var(--indigo)}
.stack-card:nth-child(even){--rz:-.38deg;border-top:3px solid var(--copper)}
.stack-card.is-front{
  --rz:0deg;--ty:-12px;--rx:0;--fade:0;z-index:100!important;
  box-shadow:0 24px 52px rgba(67,56,202,.2);border-color:var(--indigo-deep);
}
.stack-card:not(.is-front){--fade:.04;--rx:1.2}
.stack-card:focus{outline:2px solid var(--indigo);outline-offset:3px}
.stack-card:focus:not(:focus-visible){outline:none}

.stack-card::before{
  content:"";position:absolute;top:0;right:0;width:var(--fold);height:var(--fold);
  background:linear-gradient(225deg,var(--indigo-soft) 50%,var(--line) 50%);
  border-radius:0 14px 0 0;pointer-events:none;opacity:.85;
}
.stack-card.is-front::before{background:linear-gradient(225deg,var(--copper-soft) 50%,var(--indigo) 50%);opacity:1}

.card-meta{display:flex;align-items:center;gap:.7rem;margin-bottom:.75rem}
.card-step{
  flex-shrink:0;width:34px;height:34px;border-radius:10px;background:var(--indigo);color:#fff;
  display:flex;align-items:center;justify-content:center;font-size:.8rem;font-weight:700;
}
.card-tag{font-size:.72rem;font-weight:600;color:var(--copper);letter-spacing:.03em;text-transform:uppercase}
.stack-card h2{font-size:1.1rem;color:var(--indigo-deep);margin-bottom:.78rem;font-weight:600;line-height:1.4}
.stack-card p{margin-bottom:.92rem;text-align:justify;color:#312e81}
.stack-card ul{margin:.7rem 0 1rem 1.2rem;color:#312e81}
.stack-card li{margin-bottom:.42rem}
.stack-card figure{margin:1.2rem 0;border-radius:12px;overflow:hidden;border:1px solid var(--line);box-shadow:0 6px 20px rgba(67,56,202,.12)}
.stack-card figcaption{font-size:.82rem;color:var(--muted);padding:.55rem .85rem;background:var(--indigo-soft);text-align:center}

.callout{
  background:var(--copper-soft);border-left:4px solid var(--copper);
  padding:.88rem 1.05rem;border-radius:0 10px 10px 0;font-size:.93rem;margin:1.05rem 0;color:#9a3412;
}

.faq-item{margin-top:1.1rem;padding-top:1rem;border-top:1px dashed var(--line)}
.faq-item h3{font-size:.98rem;font-weight:600;color:var(--ink);margin-bottom:.52rem}
.faq-item p{font-size:.94rem;color:var(--muted)}

.bottom-links{display:flex;flex-wrap:wrap;gap:.65rem;margin-top:2.2rem;padding-top:1.5rem;border-top:1px solid var(--line)}
.bottom-links a{font-size:.85rem;color:var(--muted);background:var(--indigo-soft);padding:.38rem .88rem;border-radius:999px;border:1px solid var(--line)}
.bottom-links a:hover{color:var(--indigo);text-decoration:none;border-color:var(--indigo)}

.extra-pad{max-width:var(--content);margin:0 auto;padding:0 1.3rem 3.2rem}
.extra-pad h2{font-size:1.12rem;color:var(--indigo);margin-bottom:.85rem}
.extra-pad p{color:var(--muted);text-align:justify;font-size:.96rem}

.prose-page{max-width:var(--content);margin:0 auto;padding:2rem 1.3rem 3rem}
.prose-page h1{font-size:1.45rem;margin-bottom:1rem;color:var(--indigo)}
.prose-page p{margin-bottom:.9rem}

.error-page{max-width:var(--content);margin:4rem auto;padding:2rem 1.3rem;text-align:center}
.error-page h1{font-size:3rem;color:var(--indigo);margin-bottom:.5rem}

.site-footer{background:var(--indigo-soft);border-top:3px solid var(--indigo);padding:1.55rem 1rem;text-align:center;font-size:.82rem;color:var(--muted)}
.footer-links{display:flex;flex-wrap:wrap;justify-content:center;gap:.5rem 1rem;margin-bottom:.65rem}
.footer-links a{color:var(--muted)}
.footer-sub{font-size:.75rem;margin-top:.35rem;color:#a1a1aa}

@media(max-width:640px){
  .nav-toggle{display:flex}
  .site-nav{position:absolute;top:100%;left:0;right:0;background:#fff;border-bottom:1px solid var(--line);padding:.75rem 1rem;display:none;box-shadow:0 4px 14px rgba(0,0,0,.06)}
  .site-nav.is-open{display:block}
  .site-nav ul{flex-direction:column;gap:.5rem}
  .stack-card{margin-bottom:-1.4rem;padding:1.4rem 1.25rem;--rz:0!important}
  .hero-band h1{font-size:1.26rem}
  .section-jump{display:none}
}