*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:"Noto Sans SC",system-ui,sans-serif;background:#fff;color:#1a1a1a;line-height:1.76;font-size:16px}
a{color:#0d9488;text-decoration:none}
a:hover{text-decoration:underline}
img{max-width:100%;height:auto;display:block}

.site-header{background:#fff;border-bottom:2px solid #e6f7f5;position:sticky;top:0;z-index:200}
.header-inner{max-width:1120px;margin:0 auto;padding:0 20px;display:flex;align-items:center;justify-content:space-between;position:relative}
.brand{display:flex;align-items:center;gap:10px;color:#1a1a1a;font-weight:500;font-size:.95rem}
.brand em{font-style:normal;color:#0f766e;font-weight:700}
.site-nav ul{display:flex;gap:18px;list-style:none;flex-wrap:wrap}
.site-nav a{color:#555;font-size:.9rem;padding:18px 0;display:block}
.site-nav a.active,.site-nav a:hover{color:#0f766e;font-weight:600;text-decoration:none}
.nav-toggle{display:none;background:none;border:none;cursor:pointer;padding:8px;flex-direction:column;gap:5px}
.nav-toggle span{display:block;width:22px;height:2px;background:#333;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)}

.ads-top-bar{background:#fafafa;border-bottom:1px solid #eee;padding:10px 0}
.applist-title{font-size:.78rem;color:#888;text-align:center;margin-bottom:6px}
#ads{display:flex;justify-content:center;flex-wrap:wrap;gap:12px}
.ads-item figure{text-align:center;font-size:.72rem;color:#666}
.ads-item img{border-radius:8px}

.rail-layout{max-width:1120px;margin:0 auto;padding:0 20px 52px;display:grid;grid-template-columns:1fr 210px;gap:40px;align-items:start}
.rail-main{padding:32px 0 0}
.rail-side{position:sticky;top:76px;padding:28px 0 28px 20px;border-left:3px solid #ccfbf1}
.rail-side h2{font-size:.8rem;color:#0f766e;font-weight:700;margin-bottom:18px;letter-spacing:.03em}
.rail-side ol{list-style:none;counter-reset:rail}
.rail-side li{counter-increment:rail;margin-bottom:2px}
.rail-side a{display:flex;align-items:center;gap:10px;padding:11px 0;font-size:.83rem;color:#666;transition:color .15s}
.rail-side a::before{content:counter(rail);flex-shrink:0;width:24px;height:24px;border-radius:6px;background:#f0fdfa;color:#0d9488;font-size:.72rem;font-weight:700;display:flex;align-items:center;justify-content:center;border:1px solid #99f6e4}
.rail-side a.is-active,.rail-side a:hover{color:#0f766e;text-decoration:none;font-weight:600}
.rail-side a.is-active::before,.rail-side a:hover::before{background:#0d9488;color:#fff;border-color:#0d9488}

.hero-block{padding-bottom:36px;margin-bottom:12px;border-bottom:1px dashed #d1fae5}
.hero-block .tag{display:inline-block;font-size:.72rem;color:#0f766e;border:1px solid #99f6e4;background:#f0fdfa;padding:4px 12px;border-radius:20px;margin-bottom:14px}
.hero-block h1{font-size:1.75rem;line-height:1.34;margin-bottom:16px;color:#111;max-width:700px}
.hero-block .lede{color:#333;margin-bottom:12px;text-align:justify;max-width:740px}

.ladder-step{padding:38px 0;border-bottom:1px solid #f0fdfa;scroll-margin-top:80px}
.ladder-step:last-of-type{border-bottom:none}
.step-head{display:flex;align-items:center;gap:12px;margin-bottom:12px}
.step-head .num{width:32px;height:32px;border-radius:8px;background:linear-gradient(135deg,#0d9488,#14b8a6);color:#fff;font-size:.82rem;font-weight:700;display:flex;align-items:center;justify-content:center}
.step-head .cap{font-size:.76rem;color:#0d9488;font-weight:700}
.ladder-step h2{font-size:1.16rem;margin-bottom:14px;color:#111}
.ladder-step p{margin-bottom:12px;text-align:justify;color:#333;font-size:.97rem}
.inline-fig{margin:20px 0;border:1px solid #e6f7f5;border-radius:8px;overflow:hidden}
.inline-fig figcaption{font-size:.8rem;color:#666;padding:8px 14px;background:#f0fdfa}
.tip-band{margin:18px 0;padding:14px 18px;background:#ecfdf5;border-left:4px solid #0d9488;border-radius:0 8px 8px 0;font-size:.93rem;color:#444}
.closing-note{margin-top:24px;padding:22px;background:#f0fdfa;border-radius:10px;border:1px solid #ccfbf1}
.closing-note h3{font-size:1rem;margin-bottom:10px;color:#111}
.closing-note p{font-size:.94rem;color:#444;margin-bottom:8px}

.site-footer{background:#fafafa;border-top:1px solid #eee;padding:28px 20px;text-align:center;font-size:.88rem;color:#666}
.footer-links{display:flex;flex-wrap:wrap;justify-content:center;gap:14px;margin-bottom:10px}
.footer-sub{font-size:.8rem;color:#999;margin-top:4px}

.prose-page{max-width:760px;margin:0 auto;padding:32px 20px 48px}
.prose-page h1{font-size:1.45rem;margin-bottom:16px}
.prose-page p{margin-bottom:12px;color:#333}
.error-page{text-align:center;padding:64px 20px}
.error-page h1{font-size:3.2rem;color:#0d9488;margin-bottom:12px}

@media(max-width:880px){
  .rail-layout{grid-template-columns:1fr;gap:0}
  .rail-side{position:static;padding:16px 0;border-left:none;border-bottom:1px solid #eee;overflow-x:auto}
  .rail-side ol{display:flex;gap:0;min-width:max-content}
  .rail-side li{margin:0}
  .rail-side a{padding:10px 14px;white-space:nowrap;border-right:1px solid #e6f7f5}
  .nav-toggle{display:flex}
  .site-nav{display:none;position:absolute;top:100%;left:0;right:0;background:#fff;border-bottom:1px solid #eee;padding:12px 20px;box-shadow:0 4px 12px rgba(0,0,0,.06)}
  .site-nav.is-open{display:block}
  .site-nav ul{flex-direction:column;gap:0}
}