:root{--green:#137a45;--green-dark:#0d6337;--green-soft:#eff8f3;--ink:#101713;--muted:#5d6862;--line:#dbe5df;--surface:#f7faf8;--white:#fff;--radius:14px;--container:1180px}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:80px}
body{margin:0;background:var(--white);color:var(--ink);font-family:"Microsoft YaHei","PingFang SC","Noto Sans SC",Arial,sans-serif;line-height:1.7;-webkit-font-smoothing:antialiased;overflow-x:hidden}
img{display:block;max-width:100%}
a{color:inherit;text-decoration:none}
button{font:inherit}
.container{width:min(calc(100% - 48px),var(--container));margin-inline:auto}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
.skip-link{position:fixed;left:20px;top:-60px;z-index:100;background:var(--ink);color:#fff;padding:8px 14px}.skip-link:focus{top:12px}
.site-header{position:sticky;top:0;z-index:20;background:rgba(255,255,255,.96);border-bottom:1px solid var(--line);backdrop-filter:blur(10px)}
.nav-wrap{height:72px;display:flex;align-items:center;justify-content:space-between}
.brand{display:inline-flex;align-items:center;gap:11px;font-size:19px;font-weight:750;letter-spacing:-.02em}
.brand-mark{display:grid;place-items:center;width:30px;height:34px;color:#fff;background:var(--green);font-family:Arial,sans-serif;font-size:18px;border-radius:3px 7px 7px 3px}
.site-nav{display:flex;align-items:center;gap:34px;font-size:14px}.site-nav a{color:#37413c}.site-nav a:hover,.site-nav a:focus-visible{color:var(--green)}.site-nav .nav-download{color:var(--green);font-weight:700}
.menu-toggle{display:none;background:none;border:0;padding:8px}.menu-toggle span:not(.sr-only){display:block;width:23px;height:2px;background:var(--ink);margin:5px}
.hero{padding:86px 0 96px;overflow:hidden}.hero-grid{display:grid;grid-template-columns:minmax(0,.92fr) minmax(0,1.08fr);gap:70px;align-items:center}.hero-copy{position:relative;z-index:2;min-width:0}
h1,h2,h3,p{margin-top:0}h1{font-size:clamp(42px,4vw,58px);line-height:1.18;letter-spacing:-.045em;margin-bottom:26px}.hero-title-line{color:var(--green);white-space:nowrap}
.hero-copy>p{max-width:620px;color:var(--muted);font-size:17px;line-height:1.9;margin-bottom:34px}.hero-actions{display:flex;gap:14px;flex-wrap:wrap}
.button{display:inline-flex;align-items:center;justify-content:center;gap:9px;min-height:50px;padding:0 22px;border:1px solid var(--green);border-radius:8px;font-weight:700;font-size:15px;transition:background .18s,color .18s,border-color .18s,transform .18s}.button svg{width:20px;fill:none;stroke:currentColor;stroke-width:2;stroke-linecap:round;stroke-linejoin:round}.button:hover{transform:translateY(-1px)}.button:focus-visible,.copy-code:focus-visible,.site-nav a:focus-visible,summary:focus-visible{outline:3px solid rgba(19,122,69,.2);outline-offset:3px}.button-primary{background:var(--green);color:#fff}.button-primary:hover{background:var(--green-dark)}.button-secondary{background:#fff;color:var(--green)}.button-secondary:hover{background:var(--green-soft)}
.quick-facts{list-style:none;padding:34px 0 0;margin:40px 0 0;border-top:1px solid var(--line);display:flex;gap:36px}.quick-facts li{display:flex;flex-direction:column}.quick-facts strong{font-size:16px}.quick-facts span{font-size:13px;color:var(--muted)}
.hero-visual{height:510px;position:relative}.sheet{position:absolute;margin:0;background:#fff;border:1px solid #cdd9d2;border-radius:10px;overflow:hidden}.sheet img{width:100%;height:100%;object-fit:cover}.sheet-directory{width:46%;height:66%;right:2%;top:0}.sheet-directory img{object-position:top}.sheet-example{width:75%;height:63%;left:0;bottom:0}.sheet-example img{object-position:top left}
.section{padding:104px 0}.section-heading h2{font-size:clamp(30px,3vw,42px);line-height:1.25;letter-spacing:-.035em;margin-bottom:12px}.section-heading p{color:var(--muted);margin-bottom:0}.centered{text-align:center}.materials{background:var(--surface);border-block:1px solid var(--line)}
.material-list{display:grid;grid-template-columns:repeat(5,1fr);padding:0;margin:60px 0 0;list-style:none;border-top:1px solid var(--green)}.material-list li{padding:35px 26px 12px;border-right:1px solid var(--line)}.material-list li:last-child{border-right:0}.index,.preview-number{display:block;color:var(--green);font-family:Georgia,serif;font-style:italic;font-weight:700;font-size:22px;margin-bottom:28px}.material-list h3{font-size:19px;margin-bottom:12px}.material-list p{font-size:14px;color:var(--muted);margin:0}
.split-heading{display:flex;align-items:end;justify-content:space-between;padding-bottom:26px;border-bottom:1px solid var(--line)}.split-heading>span{font-size:13px;color:var(--green);letter-spacing:.08em}.preview-row{display:grid;grid-template-columns:280px 1fr;gap:72px;align-items:center;padding:70px 0;border-bottom:1px solid var(--line)}.preview-row-reverse{grid-template-columns:1fr 330px}.preview-row-reverse .preview-copy{order:2}.preview-row-reverse .preview-frame{order:1}.preview-copy h3{font-size:26px;margin-bottom:12px}.preview-copy p{color:var(--muted);margin:0}.preview-number{margin-bottom:18px}.preview-frame{margin:0;border:1px solid #aac8b7;border-radius:var(--radius);overflow:hidden;background:#fff}.directory-frame{max-width:690px;justify-self:end;width:100%;height:430px}.directory-frame img{width:100%;height:100%;object-fit:cover;object-position:top}.example-frame{height:500px}.example-frame img{width:100%;height:100%;object-fit:cover;object-position:top left}
.download{background:var(--green-soft);border-block:1px solid #dceee3}.download-layout{display:grid;grid-template-columns:340px 1fr;gap:90px}.download-intro h2{font-size:clamp(32px,3vw,44px);line-height:1.3;margin-bottom:18px}.download-intro>p{color:var(--muted)}.download-note{font-size:13px;margin-top:36px}.download-options{border-top:1px solid var(--green)}.download-item{display:flex;align-items:center;justify-content:space-between;gap:20px;padding:24px 0;border-bottom:1px solid #cfe1d7}.download-item>div{display:grid;grid-template-columns:48px 1fr;column-gap:16px;align-items:center}.download-item h3{margin:0;font-size:19px}.download-item p{grid-column:2;margin:0;color:var(--muted);font-size:13px}.download-item code{font-family:inherit;color:var(--ink);font-weight:700}.drive-icon{grid-row:1/3;display:grid;place-items:center;width:46px;height:46px;border-radius:12px;color:#fff;font-family:Arial;font-weight:800}.quark{background:#5a3deb}.baidu{background:#2877dd}.xunlei{background:#2b69f4}.copy-code{border:0;background:none;color:var(--green);font-size:12px;padding:2px 5px;cursor:pointer;text-decoration:underline;text-underline-offset:3px}
.faq-layout{display:grid;grid-template-columns:300px 1fr;gap:100px}.faq-list{border-top:1px solid var(--line)}details{border-bottom:1px solid var(--line)}summary{cursor:pointer;list-style:none;padding:22px 42px 22px 0;font-weight:700;position:relative}summary::-webkit-details-marker{display:none}summary::after{content:"+";position:absolute;right:8px;top:19px;color:var(--green);font-size:22px;font-weight:400}details[open] summary::after{content:"−"}details p{color:var(--muted);font-size:14px;padding:0 42px 22px 0;margin:0}
.site-footer{padding:46px 0;border-top:1px solid var(--line)}.footer-inner{display:flex;justify-content:space-between;gap:40px}.footer-inner p{margin:12px 0 0;color:var(--muted);font-size:13px}.footer-inner nav{display:flex;align-items:center;gap:28px;font-size:13px;color:var(--muted)}.footer-inner nav a:hover{color:var(--green)}
.toast{position:fixed;left:50%;bottom:30px;z-index:30;transform:translate(-50%,20px);padding:9px 16px;background:var(--ink);color:#fff;border-radius:6px;font-size:13px;opacity:0;pointer-events:none;transition:.2s}.toast.show{opacity:1;transform:translate(-50%,0)}
@media (max-width:900px){.hero{padding-top:58px}.hero-grid{grid-template-columns:minmax(0,1fr);gap:50px}.hero-copy{max-width:700px;width:100%}.hero-visual{height:460px;max-width:700px;width:100%;margin:auto}.material-list{grid-template-columns:repeat(2,1fr)}.material-list li{border-bottom:1px solid var(--line)}.download-layout,.faq-layout{grid-template-columns:1fr;gap:52px}.preview-row,.preview-row-reverse{grid-template-columns:220px 1fr;gap:40px}.preview-row-reverse .preview-copy{order:1}.preview-row-reverse .preview-frame{order:2}.example-frame{height:400px}}
@media (max-width:680px){.container{width:min(calc(100% - 32px),var(--container))}.nav-wrap{height:64px}.brand{font-size:16px}.brand-mark{width:27px;height:30px;font-size:16px}.menu-toggle{display:block}.site-nav{display:none;position:absolute;left:0;right:0;top:64px;flex-direction:column;align-items:stretch;gap:0;background:#fff;border-bottom:1px solid var(--line);padding:10px 16px 18px}.site-nav.open{display:flex}.site-nav a{padding:13px 8px}.hero{padding:45px 0 68px}h1{font-size:32px;letter-spacing:-.055em;word-break:break-all}.hero-title-line{white-space:normal}.hero-copy>p{font-size:15px;overflow-wrap:anywhere;word-break:break-all}.hero-actions{display:grid}.button{width:100%}.quick-facts{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}.quick-facts strong{font-size:13px;white-space:nowrap}.quick-facts span{font-size:12px}.hero-visual{height:330px}.sheet-directory{width:52%;height:65%}.sheet-example{width:82%;height:62%}.section{padding:72px 0}.section-heading h2{font-size:30px}.material-list{grid-template-columns:1fr;margin-top:40px}.material-list li{border-right:0;padding:25px 4px;display:grid;grid-template-columns:54px 1fr}.material-list .index{grid-row:1/3;margin:0}.material-list h3{margin:0}.material-list p{grid-column:2}.split-heading{display:block}.split-heading>span{display:block;margin-top:16px}.preview-row,.preview-row-reverse{grid-template-columns:1fr;gap:25px;padding:45px 0}.preview-row .preview-copy,.preview-row .preview-frame{order:initial}.directory-frame,.example-frame{height:auto;width:100%}.directory-frame img,.example-frame img{height:auto}.download-item{align-items:stretch;flex-direction:column}.download-item .button{width:100%}.faq-layout{gap:35px}.footer-inner{flex-direction:column}.footer-inner nav{display:grid;grid-template-columns:1fr 1fr;gap:12px}}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}.button,.toast{transition:none}}