*{box-sizing:border-box}body{margin:0;font-family:"PingFang TC","Noto Sans TC",sans-serif;background:var(--bg);color:var(--ink)}button,a{font:inherit}button{cursor:pointer}button:focus-visible,a:focus-visible{outline:3px solid var(--accent);outline-offset:3px}button{border:0;border-radius:12px;padding:12px 17px;background:var(--accent);color:var(--button);font-weight:700}.ghost{background:var(--soft);color:var(--ink)}a{color:inherit;text-decoration:none}.shell{max-width:1440px;margin:auto;padding:26px 36px}.top{display:flex;align-items:center;justify-content:space-between;margin-bottom:27px}.brand{font-size:23px;letter-spacing:-1px;font-weight:850;display:flex;align-items:center;gap:10px}.logo{width:38px;height:38px;border-radius:12px;background:var(--accent);display:grid;place-items:center;color:var(--button)}.top nav{display:flex;gap:25px;font-size:14px}.tag{font-size:11px;font-weight:700;letter-spacing:1.3px;color:var(--muted);text-transform:uppercase}.demo{font-size:12px;padding:8px 12px;border:1px solid var(--line);border-radius:30px}.heading{display:flex;align-items:end;justify-content:space-between;margin-bottom:25px}h1{font-size:36px;letter-spacing:-1.5px;margin:8px 0 10px}h2{font-size:19px;margin:0 0 12px}h3{margin:0;font-size:16px}p{line-height:1.7;margin:8px 0}.muted{color:var(--muted);font-size:13px}.card{background:var(--card);border:1px solid var(--line);border-radius:24px;padding:22px;box-shadow:var(--shadow)}.grid{display:grid;gap:22px;grid-template-columns:310px minmax(420px,1fr) 270px}.label{display:flex;align-items:center;justify-content:space-between;margin-bottom:18px}.pill{font-size:11px;font-weight:700;padding:6px 9px;background:var(--soft);color:var(--accent);border-radius:8px}.phone{min-height:605px;position:relative;padding:24px}.greeting{font-size:26px;font-weight:750;margin:17px 0 6px}.upload{border:1.5px dashed var(--accent);border-radius:19px;text-align:center;padding:24px 12px;margin:24px 0;background:var(--soft)}.upload svg{width:70px;height:65px}.upload button{width:100%;margin-top:12px}.history{display:flex;gap:11px;align-items:center;padding:14px 0;border-bottom:1px solid var(--line)}.mini-icon{background:var(--soft);border-radius:11px;padding:9px;color:var(--accent);font-weight:800}.bottomnav{display:flex;justify-content:space-between;margin-top:24px;color:var(--muted);font-size:12px}.bottomnav .active{color:var(--accent);font-weight:800}.progress{display:flex;gap:6px;margin:18px 0}.progress i{height:5px;flex:1;background:var(--line);border-radius:5px}.progress i:first-child{background:var(--accent)}.question{background:var(--soft);border-radius:16px;padding:18px;margin-bottom:18px}.formula{font-family:Georgia,serif;font-size:27px;color:var(--ink);display:flex;align-items:center;gap:12px;justify-content:center}.frac{display:inline-flex;flex-direction:column;text-align:center;line-height:1.1;vertical-align:middle;min-width:30px}.frac span:first-child{border-bottom:1.5px solid currentColor;padding-bottom:4px}.frac span:last-child{padding-top:4px}.mistake{display:flex;align-items:center;gap:10px;margin-top:13px;padding-top:13px;border-top:1px solid var(--line);font-size:12px}.wrong{color:#d65e51;text-decoration:line-through}.explain{padding:16px;border-radius:14px;border-left:3px solid var(--accent);background:var(--soft);font-size:14px;min-height:111px}.actions{display:flex;gap:9px;margin:15px 0}.teacher{display:flex;gap:12px;align-items:center;margin:18px 0}.avatar{width:49px;height:49px;flex-shrink:0;border-radius:50%;background:var(--soft)}.teacher p{font-size:12px;margin:4px 0}.availability{width:7px;height:7px;border-radius:50%;background:#42b887;display:inline-block}.full{width:100%}.match-status{font-size:12px;line-height:1.6;margin-top:12px;color:var(--muted)}.boardcard{margin-top:21px;padding:18px}.toolbar{display:flex;align-items:center;gap:7px;font-size:11px;margin-bottom:12px}.toolbar button{padding:7px 9px;font-size:11px;border-radius:8px;background:var(--soft);color:var(--ink)}.toolbar button.selected{background:var(--accent);color:var(--button)}.board{position:relative;height:253px;border-radius:14px;overflow:hidden;background:var(--board);border:1px solid var(--line)}.board svg,.board canvas{position:absolute;inset:0;width:100%;height:100%}.board canvas{touch-action:none}.board svg text{font-family:"PingFang TC",sans-serif}.boardfooter{display:flex;justify-content:space-between;gap:10px;font-size:11px;margin-top:11px;color:var(--muted)}.lesson-meta{display:flex;justify-content:space-between;margin-top:18px;font-size:12px}.call{background:var(--soft);padding:15px;border-radius:15px;margin:18px 0;text-align:center}.call .avatar{margin:auto;width:68px;height:68px}.call small{display:block;margin:9px 0;font-size:12px;color:var(--muted)}.call button{padding:8px 13px;font-size:12px}.notes{font-size:13px}.notes li{margin:12px 0;line-height:1.5}.metric{padding:16px 0;border-top:1px solid var(--line);display:flex;justify-content:space-between;font-size:13px}.metric strong{font-size:20px;color:var(--accent)}.foot{display:flex;justify-content:space-between;margin-top:22px;font-size:11px;color:var(--muted)}.style-a{--bg:#f1f6f4;--ink:#193c35;--muted:#738880;--card:#fff;--accent:#167c66;--button:#fff;--soft:#eaf6ef;--line:#dce8e1;--board:#fbfffd;--shadow:0 7px 25px #163b3406}.style-b{--bg:#f4ecdf;--ink:#473c32;--muted:#93816c;--card:#fffaf1;--accent:#b4653b;--button:#fffaf2;--soft:#f6e8d5;--line:#e3d3bb;--board:#fffdf5;--shadow:4px 5px 0 #dfceb255}.style-b .shell{padding:24px 38px}.style-b .card{border-radius:9px}.style-b .grid{grid-template-columns:270px minmax(430px,1fr) 310px}.style-b .phone{grid-column:3;grid-row:1}.style-b .workspace{grid-column:2;grid-row:1}.style-b .sidebar{grid-column:1;grid-row:1}.style-b .board{background-image:linear-gradient(#e8ddcb 1px,transparent 1px);background-size:100% 28px}.style-b h1{font-family:Georgia,"Songti TC",serif;font-size:40px}.style-b .top nav{border-bottom:1px solid var(--line);padding-bottom:10px}.style-b .upload{border-style:solid;border-radius:8px}.style-b .boardcard{transform:rotate(-.4deg)}.style-c{--bg:#0b1529;--ink:#e2edf6;--muted:#8296b1;--card:#13223a;--accent:#68cddd;--button:#092135;--soft:#1b314c;--line:#29405d;--board:#0d1c33;--shadow:0 12px 35px #0002}.style-c .grid{grid-template-columns:265px minmax(430px,1fr) 305px}.style-c .phone{grid-column:1;grid-row:1;border-radius:22px}.style-c .workspace{grid-column:2;grid-row:1}.style-c .sidebar{grid-column:3;grid-row:1}.style-c .card{border-radius:16px}.style-c .heading h1{font-size:32px}.style-c .board{background-image:radial-gradient(#29405d 1px,transparent 1px);background-size:18px 18px}.style-c .boardcard{border-color:#4f91b0}.style-c .greeting{font-size:23px}.style-c .question{background:#0d1c33}.style-c .call{display:flex;align-items:center;gap:10px;text-align:left;flex-wrap:wrap}.style-c .call .avatar{width:50px;height:50px;margin:0}.style-c .call button{margin-left:auto}@media(min-width:1200px){.style-a .workspace{margin-top:0}.style-b .board{height:275px}.style-c .board{height:285px}}@media(max-width:1050px){.grid,.style-b .grid,.style-c .grid{grid-template-columns:1fr 1fr}.phone,.workspace,.sidebar,.style-b .phone,.style-b .workspace,.style-b .sidebar,.style-c .phone,.style-c .workspace,.style-c .sidebar{grid-column:auto;grid-row:auto}.workspace{grid-column:1/-1!important;grid-row:1!important}.phone{min-height:auto}.top nav{display:none}.heading{align-items:start}.heading>div:last-child{display:none}}@media(max-width:620px){.shell,.style-b .shell{padding:20px 15px}.grid,.style-b .grid,.style-c .grid{grid-template-columns:1fr}h1,.style-b h1,.style-c h1{font-size:29px}.heading{margin-bottom:20px}.demo{font-size:10px}.card{padding:17px}.toolbar{flex-wrap:wrap}.board{height:240px}.foot{display:block;line-height:1.8}.phone{min-height:auto}.formula{font-size:24px}.top{gap:10px}.brand{font-size:20px}}
@media(min-width:1051px){.shell,.style-b .shell{padding-top:22px;padding-bottom:20px}.top{margin-bottom:18px}.heading{margin-bottom:19px}h1,.style-b h1{margin:6px 0;font-size:34px}.heading p{margin-bottom:0}.workspace>.card:first-child{padding:18px}.workspace>.card:first-child .label{margin-bottom:12px}.question{padding:12px;margin-bottom:12px}.question p{margin:0 0 9px}.mistake{padding-top:9px;margin-top:9px}.explain{min-height:65px;padding:12px}.progress{margin:12px 0}.actions{margin:12px 0 0}.boardcard{margin-top:17px}.board,.style-b .board,.style-c .board{height:235px}.phone{padding:21px;min-height:605px}.upload{padding:19px 12px;margin:19px 0}.sidebar{padding:19px}.sidebar .call{margin:14px 0;padding:12px}.notes li{margin:9px 0}.match-status{font-size:11px}.sidebar .metric strong{font-size:17px}.foot{margin-top:15px}}
@media(min-width:1051px){.top{margin-bottom:12px}.heading{margin-bottom:15px}.board,.style-b .board,.style-c .board{height:205px}.phone .greeting{margin-top:12px}.phone .upload{margin:15px 0;padding:16px 12px}.phone .history{padding:11px 0}.sidebar .call .avatar{width:50px;height:50px}.sidebar .notes{margin-top:10px;margin-bottom:10px}.sidebar .call small{margin:7px 0}.sidebar .metric{padding:11px 0}}
@media(min-width:1051px){.foot{margin-top:10px}}
.style-c .workspace{display:flex;flex-direction:column}.style-c .workspace .boardcard{order:-1;margin-top:0;margin-bottom:17px}.style-c .sidebar{border-top:3px solid var(--accent)}.style-c .phone{border-left:3px solid var(--accent)}