:root{--ink:#111827;--body:#374151;--muted:#5f6b7a;--subtle:#64748b;--line:#e5e7eb;--soft:#f8fafc;--white:#fff;--accent:#4f46e5;--accent-strong:#4338ca;--accent-2:#7c3aed;--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;overflow-x:hidden}body{margin:0;color:var(--body);background:#fff;font-family:Arial,Helvetica,sans-serif;-webkit-font-smoothing:antialiased;overflow-x:hidden}body[data-lang=en] .zh,body[data-lang=zh] .en{display:none!important}a{color:inherit}.skip-link{position:fixed;top:8px;left:8px;z-index:1000;padding:10px 14px;background:#111827;color:#fff;border-radius:8px;transform:translateY(-160%)}.skip-link:focus{transform:none}
.site-header{position:sticky;top:0;z-index:50;background:#fff;border-bottom:1px solid var(--line)}.nav-wrap{width:100%;max-width:1280px;margin:0 auto;padding:16px 24px;display:flex;align-items:center;justify-content:space-between;gap:20px}.nav-left,.brand,.primary-nav,.actions{display:flex;align-items:center}.nav-left{min-width:0}.brand{gap:12px;text-decoration:none;font-size:20px;line-height:28px;font-weight:700;color:var(--ink);white-space:nowrap}.brand img{width:32px;height:auto}.primary-nav{gap:20px;margin-left:24px}.primary-nav a{font-size:14px;line-height:20px;color:#4b5563;text-decoration:none;white-space:nowrap}.primary-nav a:hover,.footer a:hover{color:var(--accent)}.actions{gap:12px;white-space:nowrap}.action,.language-button,.menu-button{font:500 14px/20px Arial,Helvetica,sans-serif;border-radius:8px;padding:8px 16px;border:1px solid #d1d5db;background:#fff;text-decoration:none;display:inline-flex;align-items:center;gap:8px;cursor:pointer}.language{position:relative}.language-button{padding:8px 12px;background:#f3f4f6;border-color:transparent}.action.demo{border:0;color:#fff;background:var(--nav-gradient);border-radius:999px}.action.online{border-color:#000;background:#000;color:#fff;border-radius:999px}.language-menu{position:absolute;right:0;top:calc(100% + 8px);min-width:140px;margin:0;padding:6px;background:#fff;border:1px solid var(--line);border-radius:8px;box-shadow:var(--shadow);list-style:none}.language-menu[hidden]{display:none}.language-menu button{width:100%;height:36px;padding:0 16px;border:0;border-radius:6px;background:#fff;text-align:left}.language-menu button[aria-selected=true]{color:var(--accent-strong);background:var(--tint);font-weight:700}.menu-button{display:none;width:40px;height:40px;padding:0;justify-content:center}.mobile-panel{display:none;border-top:1px solid var(--line);padding:18px 24px;background:#fff}.mobile-panel[hidden]{display:none}.mobile-panel a,.mobile-panel button{font:500 14px/20px Arial,Helvetica,sans-serif;text-decoration:none;border:0;background:none;text-align:left;padding:10px;color:#374151}
.container{width:min(1180px,calc(100% - 48px));margin:0 auto}.breadcrumbs{display:flex;gap:10px;align-items:center;padding:28px 0 12px;overflow-x:auto;white-space:nowrap;color:var(--subtle);font-size:15px}.breadcrumbs a{text-decoration:none}.hero{text-align:center;padding:18px 0 44px}.eyebrow{display:inline-block;padding:7px 10px;border-radius:999px;background:var(--tint);color:var(--accent-strong);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 18px;font-size:19px;line-height:1.65}.meta{display:flex;justify-content:center;gap:18px;flex-wrap:wrap;color:var(--subtle);font-size:14px}.hero-image{display:block;width:100%;max-width:1000px;height:auto;object-fit:contain;margin:34px auto 0;border:1px solid var(--line);border-radius:18px;box-shadow:var(--shadow)}
.article-layout{display:grid;grid-template-columns:minmax(0,860px) 260px;gap:58px;padding:26px 0 82px}.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;background:var(--tint);border-left:4px solid var(--accent);border-radius:0 12px 12px 0}.callout{margin:22px 0;padding:22px 24px;background:var(--tint-soft);border:1px solid #c7d2fe;border-radius:14px}.cards{display:grid;grid-template-columns:1fr 1fr;gap:16px;margin:22px 0}.card{padding:22px;background:#fff;border:1px solid var(--line);border-left:4px solid var(--accent);border-radius:4px 14px 14px 4px}.card strong{display:block;margin-bottom:8px;color:var(--ink);font-size:17px}.card p{margin:0;font-size:15px;line-height:1.6}.steps{list-style:none;padding:0;counter-reset:steps}.steps li{position:relative;min-height:72px;padding:20px 22px 20px 64px;border:1px solid var(--line);border-radius:14px;counter-increment:steps}.steps li::before{content:counter(steps);position:absolute;top:18px;left:20px;width:30px;height:30px;display:grid;place-items:center;color:#fff;background:var(--nav-gradient);border-radius:9px;font-size:14px;font-weight:700}.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);vertical-align:top;text-align:left}.table-wrap th{background:var(--soft);font-size:13px;letter-spacing:.04em;text-transform:uppercase;color:var(--ink)}.table-wrap td{font-size:15px;line-height:1.55}.cta{margin:22px 0;padding:34px;color:#e0e7ff;background:var(--cta-gradient);border-radius:18px}.cta strong{display:block;margin-bottom:10px;color:#fff;font-size:24px}.cta a{display:inline-flex;margin-top:8px;padding:11px 18px;background:#fff;color:var(--accent-strong);border-radius:999px;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;background:var(--soft);border:1px solid var(--line);border-radius:14px}.author-mark{flex:0 0 46px;height:46px;display:grid;place-items:center;color:#fff;background:var(--nav-gradient);border-radius:12px;font-weight:700}.author-box p{margin:0;font-size:14px}.toc{position:sticky;top:100px;border-left:2px solid var(--line);padding-left:22px}.toc strong{display:block;margin-bottom:10px;color:var(--subtle);font-size:12px;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 20px;padding:14px;border:1px solid var(--line);border-radius:12px}.mobile-toc a{display:block;padding:5px 0;color:var(--accent)}
.site-footer{padding:50px 0 26px;background:var(--soft);border-top:1px solid var(--line)}.footer-grid{display:grid;grid-template-columns:1.4fr repeat(4,1fr);gap:36px}.footer-brand p{max-width:260px;color:var(--muted);font-size:14px;line-height:1.6}.footer-col strong{display:block;margin-bottom:12px;color:var(--ink);font-size:13px}.footer-col a{display:flex;align-items:center;min-height:24px;margin:4px 0;color:var(--muted);font-size:13px;text-decoration:none}.legal{display:flex;justify-content:space-between;gap:20px;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:inline-flex}.mobile-panel.open{display:grid;grid-template-columns:1fr 1fr}.article-layout{grid-template-columns:1fr}.desktop-toc{display:none}.mobile-toc{display:block}.footer-grid{grid-template-columns:2fr 1fr 1fr}.footer-brand{grid-column:1/-1}}@media(max-width:767px){.nav-wrap{padding:16px}.brand{gap:8px;font-size:18px}.brand img{width:28px}.actions{gap:8px}}@media(max-width:700px){.container{width:calc(100% - 30px)}.hero h1{font-size:37px}.hero-image{border-radius:12px}.lead{font-size:17px}.article h2{font-size:26px}.article p,.article li{font-size:16px}.cards{grid-template-columns:1fr}.mobile-panel.open{grid-template-columns:1fr}.footer-grid{grid-template-columns:1fr 1fr}.footer-brand{grid-column:1/-1}.legal{flex-direction:column}.breadcrumbs{font-size:13px}}@media(max-width:639px){.desktop-optional{display:none}.actions .action.login{display:inline-flex}.cta{padding:26px}}
.action svg,.language-button svg,.menu-button svg{width:16px;height:16px;fill:none;stroke:currentColor;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round;flex:0 0 auto}.language-button .chevron{width:12px;height:12px}.action.demo{gap:6px}.related-card{display:block;color:inherit!important;text-decoration:none!important}.related-card:hover{border-color:#c7d2fe;background:var(--tint-soft)}