:root{--brand:#0088cc;--accent:#00afd7;--heading:#163e52;--text:#536b79;--line:#e2edf1;--wash:#f3f9fb}
*{box-sizing:border-box}
[hidden]{display:none!important}
body{margin:0;min-height:100vh;display:flex;flex-direction:column;background:#fff;color:var(--text);font:17px/1.85 -apple-system,BlinkMacSystemFont,"PingFang TC","Microsoft JhengHei",sans-serif;-webkit-font-smoothing:antialiased}
a{color:#007fae;text-decoration:none}
a:hover{text-decoration:underline}
a:focus-visible,summary:focus-visible{outline:3px solid var(--accent);outline-offset:5px}
.skip{position:absolute;left:16px;top:-100px;z-index:30;padding:8px 16px;background:#fff}
.skip:focus{top:8px}
.page-wrap{width:100%;max-width:1200px;margin:0 auto;padding:40px 28px 56px;flex:1}
.deeplink-layout{max-width:1000px;margin:auto;display:grid;grid-template-columns:minmax(0,1fr) minmax(280px,340px);grid-template-areas:"cover download" "content download";column-gap:64px;row-gap:32px;align-items:start}
.worksheet-cover{grid-area:cover;position:relative;isolation:isolate;overflow:hidden;min-width:0;padding:24px 28px 32px;background:linear-gradient(135deg,#f3fafd,#e4f5fc);border:1px solid #d5eaf3;border-top:4px solid var(--accent);border-radius:18px}
.worksheet-cover::before,.worksheet-cover::after{content:"";position:absolute;z-index:0;pointer-events:none}
.worksheet-cover::before{top:14px;right:16px;width:100px;height:88px;background:radial-gradient(circle,#fff 2px,transparent 2.5px) 0 0/12px 12px}
.worksheet-cover::after{right:-52px;bottom:-66px;width:180px;height:180px;border-radius:50%;background:#bce8f6}
.worksheet-cover>*{position:relative;z-index:1}
.cover-top{display:flex;align-items:center;justify-content:space-between;gap:16px;margin-bottom:20px}
.cover-top img{object-fit:contain;width:80px;height:40px}
.grade-label{color:#007fae;font-size:14px;font-weight:600;letter-spacing:.06em}
.cover-subject{margin:0 0 14px;color:#007fae;font-size:18px;line-height:1.65;font-weight:600}
.worksheet-cover h2{display:inline-block;max-width:100%;margin:0;padding:10px 16px;background:var(--brand);border-radius:12px;color:#fff;font-size:30px;line-height:1.5;font-weight:650;overflow-wrap:anywhere}
.open-content{grid-area:content;min-width:0;padding-top:2px}
.section-title{position:relative;padding-left:18px;margin:0 0 22px;color:var(--heading);font-size:30px;line-height:1.5;font-weight:650}
.section-title::before{content:"";position:absolute;left:0;top:.25em;bottom:.25em;width:4px;border-radius:3px;background:var(--accent)}
.open-content>p,.sc-intro p{margin:0 0 26px;line-height:1.9}
.button-primary{display:inline-flex;align-items:center;justify-content:center;gap:16px;max-width:100%;min-height:48px;padding:11px 22px;background:var(--brand);border:1px solid var(--brand);border-radius:6px;color:#fff;font-size:16px;font-weight:600;text-align:center}
.button-primary:hover{background:#0077b3;color:#fff;text-decoration:none}
.download-aside{grid-area:download;min-width:0;text-align:center}
.download-section{margin:0}
.download-label{margin:0 0 14px;color:var(--heading);font-size:16px}
.store-badges{display:flex;align-items:center;gap:12px}
.store-badges a{display:block;width:calc(50% - 6px);max-width:190px;line-height:0}
.store-badges img{display:block;width:100%;height:auto}
.qr-section{margin-top:28px;text-align:center;padding:0 12px}
.qr-section canvas{display:block;width:280px;max-width:100%;height:auto;margin:auto;image-rendering:pixelated}
.qr-section p{margin:10px 0 0;color:#718894;font-size:14px}
.site-footer{border-top:1px solid var(--line);background:var(--wash);padding:20px 28px;text-align:center;color:#718894;font-size:13px}
.site-footer a{color:inherit}
.sc-brand{display:flex;align-items:center;gap:14px;color:#fff;font-size:27px;font-weight:600;line-height:1.4}
.sc-brand img{display:block;width:56px;height:56px;border-radius:10px}
.sc-brand:hover{color:#fff}
.sc-main{display:flex;align-items:flex-start;padding-top:64px}
.sc-intro{width:100%;max-width:820px;margin:0 auto;display:grid;grid-template-columns:168px minmax(0,1fr);gap:40px;align-items:start}
.app-icon{width:128px;height:128px;border-radius:24px}
.sc-features{list-style:none;padding:0;margin:0 0 30px;display:grid;grid-template-columns:1fr 1fr;gap:22px 28px}
.sc-features strong{display:block;color:var(--heading);font-size:18px;margin-bottom:4px}
.sc-features span{display:block;font-size:15px;line-height:1.8}
@media(max-width:600px){.sc-features{grid-template-columns:1fr;gap:18px}}
@media(max-width:800px){.page-wrap{padding:28px 24px 40px}.deeplink-layout{column-gap:30px;grid-template-columns:minmax(0,1fr) minmax(240px,280px)}.section-title{font-size:26px}.worksheet-cover{padding:20px}.worksheet-cover h2{font-size:26px}.sc-brand{font-size:24px}.sc-brand img{width:48px;height:48px}}
@media(max-width:600px){body{font-size:16px}.page-wrap{padding:22px 22px 36px}.deeplink-layout{max-width:440px;grid-template-columns:minmax(0,1fr);grid-template-areas:"cover" "content" "download";gap:26px}.worksheet-cover{padding:18px 22px 26px}.cover-top{margin-bottom:10px}.cover-subject{font-size:17px;margin-bottom:12px}.worksheet-cover h2{font-size:26px}.section-title{font-size:25px;margin-bottom:16px}.open-content>p{margin-bottom:20px}.button-primary{width:100%;padding:12px 14px}.download-aside{padding-top:20px;border-top:1px solid var(--line);text-align:left}.store-badges a{max-width:150px}.qr-section{margin-top:26px}.sc-main{padding-top:36px}.sc-intro{grid-template-columns:1fr;gap:26px;max-width:440px}.app-icon{width:96px;height:96px;border-radius:18px}.sc-brand{gap:10px;font-size:21px}.sc-brand img{width:44px;height:44px}.site-footer{padding:16px 22px}}