:root{--paper:#f6f5ef;--ink:#20382f;--green:#235844;--muted:#6c786f;--line:#dce1d7;--orange:#ba613a}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--paper);color:var(--ink);font-family:"PingFang SC","Microsoft YaHei",system-ui,sans-serif}button,input,a{-webkit-tap-highlight-color:transparent}button,a{touch-action:manipulation}button{font:inherit;cursor:pointer}a{color:inherit;text-decoration:none}button:focus-visible,a:focus-visible,input:focus-visible{outline:3px solid var(--orange);outline-offset:4px}button{border:0}button:disabled{cursor:default;opacity:.36}[hidden]{display:none!important}.masthead{min-height:88px;padding:16px 4.2%;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;gap:20px}.brand{display:flex;gap:13px;align-items:center;font-size:19px;font-weight:650;letter-spacing:1px}.brand-mark{display:grid;place-items:center;width:48px;height:48px;background:var(--green);color:#fff;border-radius:13px;font-size:28px;font-weight:550}.brand small{display:block;font-size:12px;letter-spacing:2px;color:var(--muted);font-weight:450;margin-top:5px}.header-right{display:flex;align-items:center;gap:12px;color:var(--muted);font-size:14px}.live-dot{width:7px;height:7px;border-radius:50%;background:#649776}.quiet{min-height:48px;padding:10px 18px;background:transparent;border:1px solid var(--line);border-radius:9px;color:var(--green);margin-left:18px;font-size:15px}main{max-width:1800px;margin:auto;padding:0 4.2%}.intro{display:flex;justify-content:space-between;align-items:center;gap:40px;padding:35px 0 29px}.eyebrow{margin:0 0 13px;font-size:11px;font-weight:650;letter-spacing:2.4px;color:var(--orange)}.eyebrow span{margin:0 9px;color:#adb6a9}h1{font-size:clamp(30px,2.7vw,48px);letter-spacing:-1.5px;margin:0 0 12px;line-height:1.4;font-weight:630}h1 span{color:var(--green)}.lead{margin:0;color:var(--muted);font-size:15px;line-height:1.7}.intro-aside{display:flex;gap:25px;align-items:center;flex-shrink:0}.aside-number{font-family:Georgia,serif;font-size:62px;line-height:1;display:block}.aside-number span{display:block;margin-top:10px;font:12px "Microsoft YaHei",sans-serif;letter-spacing:1px;color:var(--muted)}.aside-line{height:62px;width:1px;background:var(--line)}.intro-aside p{font-size:14px;line-height:1.9;margin:0;color:var(--muted)}.intro-aside p span{display:block}.toolbar{display:flex;justify-content:space-between;align-items:center;gap:22px;border-top:1px solid var(--line);padding:18px 0 12px}.tabs{display:flex;gap:6px;background:#e9ece3;border-radius:12px;padding:5px}.tabs button{min-height:48px;padding:10px 22px;background:transparent;color:var(--muted);border-radius:8px;font-size:16px;font-weight:600}.tabs button span{font-size:12px;margin-left:7px;font-weight:450}.tabs button.active{background:var(--green);color:#fff;box-shadow:0 3px 8px #23584414}.search{display:flex;align-items:center;gap:12px;width:340px;min-height:50px;border:1px solid var(--line);border-radius:10px;padding:0 15px;background:#fff9}.search>span{font-size:28px;color:var(--muted)}.search input{font:inherit;font-size:14px;min-width:0;width:100%;border:0;background:transparent;padding:12px 0;color:var(--ink)}.search input:focus{outline:0}.search:focus-within{outline:2px solid var(--green)}.search button{font-size:24px;background:none;color:var(--muted);min-width:36px;min-height:44px}.filterbar{display:flex;justify-content:space-between;gap:20px;align-items:center;margin-bottom:17px}.filters{display:flex;gap:10px;flex-wrap:wrap}.filters button{min-height:48px;border-radius:8px;padding:10px 19px;background:transparent;color:var(--muted);font-size:15px}.filters button.active{background:#dfe8db;color:var(--green);font-weight:650}.filterbar p{font-size:13px;color:var(--muted);margin:0;white-space:nowrap}.grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:21px}.card{border:1px solid var(--line);border-radius:16px;background:#fff;overflow:hidden;display:flex;flex-direction:column;box-shadow:0 4px 14px #20382f03;transition:transform .18s,box-shadow .18s}.card:hover{transform:translateY(-3px);box-shadow:0 12px 28px #20382f12}.card-open{padding:0;background:transparent;width:100%;text-align:left;display:flex;flex-direction:column;flex:1;color:inherit}.preview{width:100%;aspect-ratio:2.85;position:relative;background:#e3eadd;overflow:hidden;display:block}.preview img{width:100%;height:100%;object-fit:cover;object-position:center;display:block;transition:transform .3s}.card:hover .preview img{transform:scale(1.025)}.preview::after{content:"";position:absolute;inset:0;box-shadow:inset 0 -20px 24px #19332d08;pointer-events:none}.card-label{position:absolute;left:13px;top:12px;border-radius:5px;padding:6px 10px;font-size:11px;letter-spacing:1px;font-weight:600;background:#fffef3ed;color:var(--green);z-index:1;backdrop-filter:blur(8px)}.card-number{position:absolute;right:13px;top:11px;color:white;font-family:Georgia,serif;font-size:17px;text-shadow:0 1px 5px #0009}.card-body{padding:17px 20px 16px;width:100%}.card h2{font-size:22px;line-height:1.35;margin:0 0 7px;font-weight:620;letter-spacing:-.4px}.card p{font-size:13px;color:var(--muted);line-height:1.7;margin:0;min-height:22px}.card-bottom{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-top:14px}.card-bottom small{font-size:12px;color:#758773}.card-bottom .enter{font-size:14px;color:var(--green);font-weight:650}.card-bottom .arrow{margin-left:15px;font-size:19px}.paging{display:flex;justify-content:space-between;align-items:center;gap:15px;padding:22px 0 16px}.paging>p{color:var(--muted);font-size:13px;margin:0}.page-controls,.pages{display:flex;gap:7px;align-items:center}.page-controls button{background:transparent;min-height:48px;min-width:46px;padding:9px 14px;color:var(--green);font-size:14px;border-radius:8px}.pages button.active{background:var(--green);color:#fff}.guide-button{min-height:48px;background:transparent;color:var(--muted);font-size:13px}.empty{padding:80px 20px;text-align:center;color:var(--muted);font-size:20px}.empty button{display:block;margin:24px auto 0;padding:15px 25px;background:var(--green);color:#fff;border-radius:8px}footer{max-width:1800px;margin:auto;padding:15px 4.2% 24px;color:#899385;font-size:11px;letter-spacing:1px;display:flex;justify-content:space-between;gap:15px}.viewer{position:fixed;inset:0;z-index:10;background:var(--paper);display:flex;flex-direction:column}.viewer-toolbar{min-height:72px;display:flex;align-items:center;gap:24px;padding:10px 18px;border-bottom:1px solid var(--line);flex-shrink:0}.back{min-height:50px;border-radius:9px;padding:12px 23px;background:var(--green);color:white;font-weight:600;font-size:16px;white-space:nowrap}.viewer-title{display:flex;gap:14px;align-items:center;flex:1}.viewer-title strong{font-size:18px}.viewer-title span{font-size:12px;color:var(--muted)}.viewer-actions{display:flex;gap:7px}.viewer-actions button,.viewer-actions a{display:flex;align-items:center;justify-content:center;min-height:48px;padding:10px 17px;color:var(--green);font:inherit;font-size:14px;background:#e9ece3;border-radius:8px}.tip-panel{padding:16px 28px;font-size:16px;line-height:1.7;background:#eef0e4;color:var(--ink);border-bottom:1px solid var(--line)}.tip-panel small{display:block;color:var(--muted);font-size:13px;margin-top:6px}.tip-panel a{display:inline-block;margin:10px 10px 0 0;background:var(--green);color:#fff;padding:11px 18px;border-radius:8px;min-height:48px}iframe{width:100%;flex:1;min-height:0;border:0;background:white}dialog{border:1px solid var(--line);border-radius:20px;padding:40px;max-width:640px;width:calc(100% - 32px);color:var(--ink);background:var(--paper);box-shadow:0 20px 100px #102a2140}dialog::backdrop{background:#102a2180;backdrop-filter:blur(5px)}dialog h2{font-size:29px;margin:0 0 25px}.close-help{position:absolute;right:12px;top:10px;background:transparent;color:var(--muted);font-size:26px;min-height:48px;min-width:48px}dialog ol{padding-left:24px;margin:0}dialog li{padding:0 0 20px 9px}dialog li strong{font-size:18px}dialog li span{display:block;color:var(--muted);font-size:14px;margin-top:7px;line-height:1.7}.help-note{font-size:13px;line-height:1.8;color:var(--muted);background:#e9ece3;padding:16px;border-radius:9px;margin:0 0 25px}#toast{position:fixed;bottom:24px;left:50%;transform:translateX(-50%);padding:14px 25px;border-radius:10px;background:var(--ink);color:white;z-index:30;font-size:15px}@media(min-width:1600px){.intro{padding:34px 0 29px}.preview{aspect-ratio:3}.card h2{font-size:23px}.card-body{padding:17px 22px 16px}.card p{font-size:14px}.card-bottom{margin-top:14px}}@media(max-width:1100px){.intro-aside{display:none}.header-right>span{display:none}.grid{grid-template-columns:repeat(2,minmax(0,1fr))}.intro{padding:28px 0}h1{font-size:32px}.viewer-title span{display:none}.viewer-toolbar{gap:14px}.viewer-actions button,.viewer-actions a{padding:10px 11px}.preview{aspect-ratio:2.4}}@media(max-width:650px){.masthead{padding:12px 5%;min-height:74px}.brand{font-size:14px;letter-spacing:0}.brand-mark{width:40px;height:40px;font-size:24px}.brand small{font-size:10px}.quiet{font-size:12px;padding:8px 10px;min-height:44px;margin:0}main{padding:0 5%}.intro{padding:25px 0 20px}.eyebrow{font-size:9px;letter-spacing:1.1px}h1{font-size:28px;line-height:1.5;letter-spacing:-1px}h1 span{display:block}.lead{font-size:13px}.toolbar{align-items:stretch;flex-direction:column;gap:12px}.tabs button{flex:1;font-size:14px;padding:8px 14px}.search{width:100%}.filterbar{align-items:flex-start;gap:0}.filters{gap:0}.filters button{font-size:13px;padding:9px 12px}.filterbar p{display:none}.grid{grid-template-columns:1fr;gap:18px}.preview{aspect-ratio:2.5}.card-body{padding:16px 20px}.paging{flex-wrap:wrap;justify-content:center}.paging>p{width:100%;text-align:center}.guide-button{display:none}.page-controls button{min-width:42px;padding:9px 11px}footer{padding:10px 5% 25px;line-height:1.7;display:block}footer span{display:block}.viewer-toolbar{flex-wrap:wrap;padding:8px;gap:8px;min-height:0}.back{min-height:46px;font-size:13px;padding:10px 12px}.viewer-title{justify-content:flex-end}.viewer-title strong{font-size:14px}.viewer-actions{width:100%;justify-content:flex-end}.viewer-actions button,.viewer-actions a{min-height:40px;font-size:12px}.tip-panel{font-size:13px;padding:12px 16px}dialog{padding:30px 24px}dialog h2{font-size:24px}}@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}
@media(min-width:1101px) and (min-height:850px){.masthead{min-height:76px;padding-top:12px;padding-bottom:12px}.intro{padding:22px 0 20px}.intro .eyebrow{margin-bottom:8px}.intro h1{font-size:40px;margin-bottom:8px}.toolbar{padding-top:13px;padding-bottom:9px}.filterbar{margin-bottom:13px}.card-body{padding-top:13px;padding-bottom:12px}.card-bottom{margin-top:10px}.paging{padding-top:14px;padding-bottom:8px}footer{padding-top:10px;padding-bottom:15px}}
@media(min-width:1101px) and (min-height:850px){.intro{padding-top:18px;padding-bottom:16px}.preview{aspect-ratio:3.2}}

.mathweek-hub{display:inline-flex;align-items:center;min-height:48px;color:var(--green);font-size:13px;padding:8px 12px}.ellipsis{color:var(--muted);padding:0 5px}.paging{flex-wrap:wrap}@media(max-width:650px){.mathweek-hub{font-size:12px}.page-controls #prev,.page-controls #next{font-size:0;min-width:38px;padding:9px}.page-controls #prev::after{content:"←";font-size:18px}.page-controls #next::after{content:"→";font-size:18px}.pages{gap:3px}.page-controls{gap:3px}.pages button{min-width:36px;padding:9px}.ellipsis{padding:0 2px}}