:root{color-scheme:light dark;--bg:#f6f8fc;--card:#fff;--ink:#172033;--muted:#5d6a7e;--line:#dce4f0;--blue:#2458d6;--blue-ink:#fff;--tint:#e8efff;--accent:#0f7b6c;--shadow:0 10px 30px rgba(31,54,104,.07)}
@media (prefers-color-scheme:dark){:root{--bg:#0e1420;--card:#161e2e;--ink:#e8edf6;--muted:#9aa7bd;--line:#26324a;--blue:#6f97ff;--blue-ink:#0b1220;--tint:#1b2a4a;--accent:#4fd1bd;--shadow:none}}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font:17px/1.65 Inter,ui-sans-serif,system-ui,-apple-system,"Segoe UI","Noto Sans SC","Noto Sans JP","Noto Sans KR",sans-serif}
a{color:var(--blue)}
.wrap{max-width:760px;margin:0 auto;padding:0 16px}
.site-header{background:var(--card);border-bottom:1px solid var(--line)}
.site-header .bar{max-width:1040px;display:flex;align-items:center;justify-content:space-between;height:60px}
.brand{display:flex;align-items:center;gap:10px;font-weight:750;color:var(--ink);text-decoration:none}
.mark{font-family:"PingFang SC","Noto Sans SC","Microsoft YaHei",sans-serif;display:grid;place-items:center;width:30px;height:30px;border-radius:9px;background:var(--blue);color:var(--blue-ink);font-weight:800}
.site-header nav{display:flex;align-items:center;gap:18px}
.site-header nav a{color:var(--muted);text-decoration:none;font-weight:600;font-size:15px}
.site-header .nav-cta{color:var(--blue-ink);background:var(--blue);padding:8px 14px;border-radius:10px}
.article{padding-top:26px;padding-bottom:56px}
.crumbs{font-size:14px;color:var(--muted);margin-bottom:14px}
.crumbs a{color:var(--muted)}.crumbs i{font-style:normal;opacity:.6;margin:0 4px}
h1{font-size:clamp(28px,5vw,40px);line-height:1.15;letter-spacing:-.025em;margin:.1em 0 .35em}
h2{font-size:clamp(22px,3.4vw,27px);line-height:1.25;letter-spacing:-.015em;margin:2em 0 .5em}
h3{font-size:19px;margin:1.6em 0 .4em}
.byline{color:var(--muted);font-size:14px;margin:0 0 20px}
.lead{font-size:19px;color:var(--muted)}
.answer{background:var(--card);border:1px solid var(--line);border-left:5px solid var(--blue);border-radius:14px;padding:16px 20px;box-shadow:var(--shadow);margin:0 0 22px}
.answer p{margin:.2em 0 0;font-size:18px}
.answer-label{font-size:12px;font-weight:800;letter-spacing:.08em;text-transform:uppercase;color:var(--blue)}
.cta-card{display:flex;flex-wrap:wrap;gap:16px 24px;align-items:center;justify-content:space-between;background:linear-gradient(135deg,var(--tint),var(--card));border:1px solid var(--line);border-radius:18px;padding:20px 22px;margin:26px 0}
.cta-card h2{font-size:19px;margin:0 0 4px}.cta-card p{margin:0;color:var(--muted);font-size:15.5px}
.cta-card .fine{font-size:13.5px;margin-top:6px}
.cta-top{margin-top:0}
.cta-buttons{display:flex;flex-wrap:wrap;gap:10px}
.btn{display:inline-block;padding:11px 18px;border-radius:12px;font-weight:700;font-size:15.5px;text-decoration:none;border:1px solid transparent;line-height:1.2}
.btn-primary{background:var(--blue);color:var(--blue-ink)}
.btn-primary:hover{filter:brightness(1.08)}
.btn-ghost{background:transparent;color:var(--blue);border-color:var(--blue)}
.btn-ghost:hover{background:var(--tint)}
.btn:focus-visible,a:focus-visible,summary:focus-visible{outline:3px solid var(--blue);outline-offset:2px}
.toc{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:14px 20px;margin:0 0 8px;font-size:15.5px}
.toc ol{margin:.4em 0 0;padding-left:1.2em}
.toc li{margin:.15em 0}
.langs{font-size:14.5px;color:var(--muted);margin:0 0 14px}
.prose p,.prose li{max-width:68ch}
.prose ul,.prose ol{padding-left:1.35em}
.prose li{margin:.3em 0}
.prose code,.py{font-family:ui-monospace,SFMono-Regular,Menlo,monospace;font-size:.92em}
.prose code{background:var(--tint);padding:.1em .4em;border-radius:6px}
.py{color:var(--accent);font-weight:600;font-family:inherit;font-size:1em}
.zh{font-family:"PingFang SC","Noto Sans SC","Microsoft YaHei",sans-serif}
.example{margin:18px 0;padding:18px 20px;background:var(--card);border:1px solid var(--line);border-radius:14px;box-shadow:var(--shadow)}
.example-zh{font-family:"PingFang SC","Noto Sans SC","Microsoft YaHei",sans-serif;font-size:26px;line-height:1.4}
.example-py{color:var(--accent);font-size:19px;font-weight:600;margin-top:2px}
.table-wrap{overflow-x:auto;margin:16px 0;border:1px solid var(--line);border-radius:14px;background:var(--card)}
table{border-collapse:collapse;width:100%;font-size:15.5px}
th,td{text-align:left;padding:10px 14px;border-bottom:1px solid var(--line);vertical-align:top}
th{background:var(--tint);font-size:13.5px;text-transform:none;white-space:nowrap}
tr:last-child td{border-bottom:0}
.note{border-left:4px solid var(--accent);background:var(--card);padding:10px 16px;border-radius:0 12px 12px 0;margin:18px 0;color:var(--ink)}
.steps{counter-reset:s;list-style:none;padding:0!important}
.steps li{counter-increment:s;position:relative;padding:12px 14px 12px 54px;margin:10px 0;background:var(--card);border:1px solid var(--line);border-radius:14px}
.steps li::before{content:counter(s);position:absolute;left:14px;top:12px;width:28px;height:28px;border-radius:50%;background:var(--blue);color:var(--blue-ink);display:grid;place-items:center;font-weight:800;font-size:14px}
.faq details{background:var(--card);border:1px solid var(--line);border-radius:12px;margin:10px 0;padding:0 16px}
.faq summary{cursor:pointer;font-weight:650;padding:13px 0;list-style-position:outside}
.faq details p{margin:0 0 14px;color:var(--ink)}
.related ul{list-style:none;padding:0;display:grid;gap:10px}
.related li a{display:block;padding:12px 16px;background:var(--card);border:1px solid var(--line);border-radius:12px;text-decoration:none;font-weight:600}
.hub-list{list-style:none;padding:0;display:grid;gap:12px}
.hub-list a{display:block;padding:14px 18px;background:var(--card);border:1px solid var(--line);border-radius:14px;text-decoration:none;color:var(--ink)}
.hub-list a:hover{border-color:var(--blue)}
.hub-list strong{display:block;color:var(--blue)}
.hub-list span{color:var(--muted);font-size:15px}
.site-footer{border-top:1px solid var(--line);padding:26px 0;color:var(--muted);font-size:14.5px}
.foot-links{display:flex;flex-wrap:wrap;gap:6px 18px}.foot-links a{color:var(--muted)}
@media (max-width:560px){body{font-size:16.5px}.cta-card{padding:16px}.btn{flex:1 1 100%;text-align:center}}