:root{--ink:#111827;--body:#374151;--muted:#5f6b7a;--subtle:#64748b;--line:#e5e7eb;--soft:#f8fafc;--white:#fff;--accent:#4f46e5;--accent-strong:#4338ca;--tint:#eef2ff;--tint-soft:#f5f7ff;--nav-gradient:linear-gradient(135deg,#3563f4,#5b3df5);--cta-gradient:linear-gradient(135deg,#172554,#4f46e5 60%,#7c3aed);--shadow:0 18px 55px rgba(15,23,42,.09)}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;color:var(--body);background:#fff;font-family:Arial,Helvetica,sans-serif;-webkit-font-smoothing:antialiased}body[data-lang="en"] .zh,body[data-lang="zh"] .en{display:none!important}a{color:inherit}.skip-link{position:fixed;top:-80px;left:16px;z-index:100;padding:12px 16px;border-radius:8px;color:#fff;background:#111827}.skip-link:focus{top:12px}
.site-header{position:sticky;top:0;z-index:50;border-bottom:1px solid var(--line);background:#fff}.nav-shell{display:flex;align-items:center;justify-content:space-between;gap:16px;width:100%;max-width:1280px;margin:0 auto;padding:16px 24px}.nav-left,.brand,.primary-nav,.nav-actions{display:flex;align-items:center}.nav-left{min-width:0}.brand{gap:12px;color:var(--ink);font-size:20px;font-weight:700;line-height:28px;text-decoration:none;white-space:nowrap}.brand img{width:32px;height:auto}.primary-nav{gap:20px;margin-left:24px}.primary-nav a{color:#4b5563;font-size:14px;line-height:20px;text-decoration:none;white-space:nowrap}.primary-nav a:hover,.site-footer a:hover{color:var(--accent)}.nav-actions{gap:12px}.action,.lang-button,.menu-button{border:0;font:500 14px/20px Arial,Helvetica,sans-serif;text-decoration:none;white-space:nowrap;cursor:pointer}.action{padding:8px 16px;border-radius:8px}.action-outline{border:1px solid #d1d5db;background:#fff}.action-online{border-radius:999px;color:#fff;background:#000}.action-login,.lang-button{display:flex;align-items:center;gap:8px}.lang-wrap{position:relative}.lang-button{padding:8px 12px;border-radius:8px;color:#111827;background:#f3f4f6}.lang-menu{position:absolute;top:44px;right:0;display:none;min-width:140px;padding:5px;border:1px solid var(--line);border-radius:8px;background:#fff;box-shadow:var(--shadow)}.lang-menu.open{display:block}.lang-option{width:100%;height:36px;padding:0 16px;border:0;border-radius:6px;background:#fff;text-align:left;cursor:pointer}.lang-option[aria-selected="true"]{color:var(--accent-strong);background:var(--tint);font-weight:700}.menu-button{display:none;align-items:center;justify-content:center;width:40px;height:40px;border:1px solid #d1d5db;border-radius:8px;background:#fff}.mobile-panel{display:none;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px;padding:18px 24px 22px;border-top:1px solid var(--line);background:#fff}.mobile-panel.open{display:grid}.mobile-panel a,.mobile-panel button{padding:10px 12px;border:1px solid var(--line);border-radius:8px;color:#374151;background:#fff;font:500 14px/20px Arial,Helvetica,sans-serif;text-align:left;text-decoration:none}
.container{width:min(1180px,calc(100% - 48px));margin:0 auto}.breadcrumbs{display:flex;align-items:center;gap:10px;overflow-x:auto;padding-top:28px;padding-bottom:12px;color:var(--subtle);font-size:15px;white-space:nowrap}.breadcrumbs a{color:var(--subtle);text-decoration:underline;text-underline-offset:3px}.hero{padding:18px 0 44px;text-align:center}.eyebrow{display:inline-flex;padding:7px 10px;border-radius:999px;color:var(--accent-strong);background:var(--tint);font-size:12px;font-weight:700;letter-spacing:.07em;text-transform:uppercase}.hero h1{max-width:980px;margin:18px auto 14px;color:var(--ink);font-size:50px;line-height:1.1;letter-spacing:-.045em}.lead{max-width:850px;margin:0 auto;font-size:19px;line-height:1.65}.meta{display:flex;justify-content:center;flex-wrap:wrap;gap:18px;margin-top:18px;color:var(--subtle);font-size:14px}.review-note{color:#92400e}.hero figure{margin:34px 0 0}.hero img{display:block;width:100%;aspect-ratio:1.777;border:1px solid var(--line);border-radius:18px;object-fit:cover;box-shadow:var(--shadow)}figcaption{margin-top:10px;color:var(--subtle);font-size:13px;line-height:1.55}
.article-layout{display:grid;grid-template-columns:minmax(0,860px) 260px;gap:58px;padding:26px 0 82px}.article{min-width:0}.article section{padding:42px 0;border-top:1px solid var(--line)}.article section:first-child{padding-top:10px;border-top:0}.article h2{margin:0 0 18px;color:var(--ink);font-size:30px;line-height:1.25;letter-spacing:-.025em}.article p,.article li{font-size:17px;line-height:1.72}.article p{margin:0 0 18px}.article li+li{margin-top:8px}.article a{color:var(--accent);text-decoration:underline;text-underline-offset:3px}.quick-answer{padding:22px 24px;border-left:4px solid var(--accent);border-radius:0 12px 12px 0;background:var(--tint)}.quick-answer p:last-child{margin-bottom:0}.callout{margin:22px 0;padding:22px 24px;border:1px solid #c7d2fe;border-radius:14px;background:var(--tint-soft)}.cards{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px;margin:22px 0}.card{padding:22px;border:1px solid var(--line);border-left:4px solid var(--accent);border-radius:4px 14px 14px 4px;background:#fff}.card strong{display:block;margin-bottom:8px;color:var(--ink);font-size:17px}.card p{margin:0;font-size:15px;line-height:1.6}.metric-strip{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px;margin:22px 0}.metric{padding:18px;border:1px solid var(--line);border-radius:14px;background:#fff}.metric b{display:block;margin-bottom:6px;color:var(--accent);font-size:22px}.metric span{display:block;color:var(--muted);font-size:13px;line-height:1.45}.table-wrap{overflow-x:auto;margin:22px 0;border:1px solid var(--line);border-radius:14px}.table-wrap table{width:100%;min-width:690px;border-collapse:collapse}.table-wrap th,.table-wrap td{padding:15px 16px;border-bottom:1px solid var(--line);font-size:15px;line-height:1.55;text-align:left;vertical-align:top}.table-wrap th{color:var(--ink);background:var(--soft);font-size:13px;letter-spacing:.04em;text-transform:uppercase}.table-wrap tr:last-child td{border-bottom:0}.steps{margin:22px 0;padding:0;list-style:none;counter-reset:step}.steps li{position:relative;margin:0 0 14px;padding:20px 22px 20px 64px;border:1px solid var(--line);border-radius:14px;background:#fff}.steps li:before{position:absolute;top:20px;left:20px;display:grid;place-items:center;width:30px;height:30px;border-radius:9px;color:#fff;background:var(--nav-gradient);font:700 14px Arial;counter-increment:step;content:counter(step)}.steps strong{color:var(--ink)}.code-block{overflow-x:auto;margin:22px 0;padding:18px 20px;border-radius:12px;color:#e5e7eb;background:#111827;font:14px/1.65 Consolas,Monaco,monospace}.cta{margin:26px 0;padding:34px;border-radius:18px;color:#e0e7ff;background:var(--cta-gradient)}.cta h2{margin-bottom:12px;color:#fff}.cta p{color:#e0e7ff}.cta a{display:inline-flex;padding:11px 18px;border-radius:999px;color:var(--accent-strong);background:#fff;font-weight:700;text-decoration:none}.faq-item{padding:22px 0;border-bottom:1px solid var(--line)}.faq-item strong{display:block;margin-bottom:8px;color:var(--ink);font-size:18px}.faq-item p{margin:0}.author-box{display:flex;gap:16px;padding:22px;border:1px solid var(--line);border-radius:14px;background:var(--soft)}.author-mark{display:grid;flex:0 0 46px;place-items:center;height:46px;border-radius:12px;color:#fff;background:var(--nav-gradient);font-weight:700}.author-box p{margin:0;font-size:14px}.toc{position:sticky;top:100px;padding-left:22px;border-left:2px solid var(--line)}.toc-label{margin-bottom:10px;color:var(--subtle);font-size:12px;font-weight:700;letter-spacing:.1em;text-transform:uppercase}.toc a{display:block;padding:5px 0;color:var(--subtle);font-size:13px;line-height:1.4;text-decoration:none}.toc a.active{color:var(--accent);font-weight:700}.mobile-toc{display:none;margin:0 0 28px;padding:14px 16px;border:1px solid var(--line);border-radius:12px}.mobile-toc summary{color:var(--ink);font-weight:700;cursor:pointer}.mobile-toc a{display:block;padding:7px 0;color:var(--accent)}.disclosure{padding:16px 18px;border:1px solid #fed7aa;border-radius:12px;color:#7c2d12;background:#fff7ed}.disclosure p{margin:0;font-size:15px}
.site-footer{padding:50px 0 26px;border-top:1px solid var(--line);background:var(--soft)}.footer-grid{display:grid;grid-template-columns:1.4fr repeat(4,1fr);gap:36px}.footer-brand p{color:var(--muted);font-size:14px;line-height:1.6}.footer-title{margin-bottom:14px;color:var(--ink);font-size:13px;font-weight:700}.site-footer a{display:block;margin:10px 0;color:#475569;font-size:13px;text-decoration:none}.site-footer .brand{display:flex;margin:0;color:var(--ink);font-size:20px}.legal{display:flex;justify-content:space-between;gap:18px;margin-top:35px;padding-top:22px;border-top:1px solid var(--line);color:#475569;font-size:12px}
@media(min-width:1536px){.primary-nav{gap:24px}}@media(max-width:1279.98px){.primary-nav{display:none}.menu-button{display:flex}.article-layout{grid-template-columns:1fr}.desktop-toc{display:none}.mobile-toc{display:block}.footer-grid{grid-template-columns:2fr 1fr 1fr}}@media(max-width:767.98px){.nav-shell{padding:16px}.nav-actions{gap:8px}.brand{gap:8px;font-size:18px}.brand img{width:28px}}@media(max-width:700px){.container{width:calc(100% - 30px)}.mobile-panel{grid-template-columns:1fr}.hero h1{font-size:37px}.article h2{font-size:26px}.lead{font-size:17px}.article p,.article li{font-size:16px}.cards,.metric-strip{grid-template-columns:1fr}.hero img{border-radius:12px}.cta{padding:26px}.footer-grid{grid-template-columns:1fr 1fr}.footer-brand{grid-column:1/-1}.legal{flex-direction:column}}@media(max-width:639.98px){.nav-actions .lang-wrap,.nav-actions .action-download,.nav-actions .action-online{display:none}}@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{transition:none!important}}