:root{--bg:#f6fafc;--paper:#fff;--pale:#eaf6fa;--pale2:#edf4f8;--aqua:#25c8d1;--sky:#25b6e8;--blue:#1787db;--navy:#174b78;--title:#183a56;--body:#31485d;--muted:#687d8e;--line:#dce9f0;--footer:#123653}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:30px}body{margin:0;background:var(--bg);color:var(--body);font:16px/1.8 Arial,"PingFang SC","Microsoft YaHei",sans-serif;overflow-x:hidden}a{color:var(--navy);text-decoration-thickness:1px;text-underline-offset:4px}a:hover{color:var(--blue)}a:focus-visible,button:focus-visible,summary:focus-visible{outline:3px solid var(--aqua);outline-offset:3px}h1,h2,h3{color:var(--title);line-height:1.35;letter-spacing:-.025em}h1{font-size:clamp(32px,3.5vw,42px);margin:0 0 22px}h2{font-size:clamp(22px,2.7vw,27px);margin:0 0 19px}h3{font-size:clamp(18px,2vw,21px);margin:0 0 10px}p{margin:0 0 16px}ul,ol{padding-left:1.35em}li+li{margin-top:7px}.wrap{max-width:1180px;padding-left:28px;padding-right:28px;margin-inline:auto}.site-header{background:#fff;border-bottom:1px solid var(--line);position:relative;z-index:20}.topbar{height:72px;display:flex;align-items:center;gap:22px}.brand{display:flex;align-items:center;text-decoration:none;min-width:0}.brand-fallback{display:none;font-size:24px;font-weight:800;color:var(--navy)}.brand:has(.media--empty) .brand-fallback{display:inline}.brand:has(.media--empty) .media--empty{display:none}.topbar-kicker{margin-left:auto;font-size:13px;letter-spacing:.13em;color:var(--muted)}.entry-button{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:9px 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#9bc7d9;background:white}.quickbar{background:#fff;border-bottom:1px solid var(--line)}.quickbar-inner{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px;padding-top:15px;padding-bottom:15px}.quickbar-inner>div{display:flex;gap:8px;flex-wrap:wrap;align-items:center;font-size:13px}.quickbar strong{color:var(--title)}.quickbar a{color:var(--navy)}.topic-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px}.topic-card{background:#fff;border:1px solid var(--line);border-radius:12px;padding:22px;transition:border-color .2s}.topic-card:hover{border-color:#59bdd5}.topic-card strong{display:block;color:var(--title);font-size:18px;margin-bottom:5px}.topic-card p{color:var(--muted);font-size:14px;line-height:1.65;margin:0 0 8px}.topic-card a{font-size:14px;font-weight:700}.feature-split{display:grid;grid-template-columns:2fr 1fr;gap:22px}.feature-main,.feature-side,.panel,.note-card{background:var(--paper);border:1px solid var(--line);border-radius:14px;padding:26px}.feature-side article+article{border-top:1px solid var(--line);padding-top:18px;margin-top:20px}.feature-split h3{margin-top:0}.alternating,.two-col{display:grid;grid-template-columns:1fr 1fr;gap:32px;align-items:center}.three-col{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.three-col>*{min-width:0}.reading-path{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:18px;counter-reset:steps}.reading-step{padding:20px;background:#fff;border:1px solid var(--line);border-radius:12px}.reading-step:before{counter-increment:steps;content:"0" counter(steps);display:block;color:#148aab;font-weight:800;font-size:24px;margin-bottom:9px}.article-head{max-width:900px;margin-bottom:32px}.article-head h1{font-size:clamp(30px,3.4vw,36px)}.article-head .lead{margin-bottom:0}.prose{max-width:780px}.prose p{margin-bottom:18px}.prose h2{margin-top:42px}.prose 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@media(max-height:500px) and (max-width:980px){.mobile-bottom{position:static}.back-top{bottom:18px}body{padding-bottom:0}}@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*::before,*::after{animation-duration:.01ms!important;transition-duration:.01ms!important}}