.classroom{max-width:1180px;margin:auto;padding:0 24px 70px;font-family:"PingFang SC","Microsoft YaHei",sans-serif}.crumb{display:flex;gap:12px;align-items:center;color:#64748b;font-size:13px;margin:0 0 30px}.crumb a:hover{color:#0768d8}.classroom-hero{display:grid;grid-template-columns:1fr 300px;gap:70px;padding:40px 0 48px;border-bottom:1px solid #d8e0ea}.classroom h1{font-size:clamp(30px,3.5vw,46px);line-height:1.32;letter-spacing:-1px;margin:15px 0 22px}.classroom-hero h1 span{color:#0768d8}.hero-intro{font-size:17px;line-height:1.9;color:#46556b;max-width:650px;margin-bottom:26px}.course-facts{display:flex;gap:30px;margin-top:32px;font-size:13px;color:#5f6e82}.course-facts strong{font-size:24px;color:#102d50;margin-right:5px}.teacher-intro{align-self:center;background:#edf4fb;border:1px solid #dbe8f4;padding:20px 24px 26px;border-radius:4px;text-align:center}.teacher-intro img{width:170px;height:180px;object-fit:contain;margin:4px auto 12px}.teacher-intro h2{font-size:24px;margin:0}.teacher-intro p{font-size:13px;line-height:1.85;color:#5d6c7e;margin:9px 0 0}.teacher-intro .teacher-eyebrow{font-size:12px;text-align:left;letter-spacing:2px;color:#0768d8;margin:0}.teacher-intro .teacher-org{font-size:15px;color:#203c5e;margin:3px 0 10px}.lesson-section{padding-top:42px}.section-top{display:flex;justify-content:space-between;align-items:end;gap:30px}.section-top h2{font-size:28px;margin:5px 0 0}.section-top .eyebrow{margin:0;font-size:12px}.lesson-search{font-size:12px;color:#5d6c7e;display:grid;gap:5px}.lesson-search input{width:300px;border:1px solid #c4d2df;border-radius:5px;padding:11px 14px;background:white;color:#172b42;font-size:14px}.filter-row{display:flex;gap:9px;align-items:center;flex-wrap:wrap;margin:25px 0}.filter-row button{border:1px solid #d8e0ea;background:#fff;color:#41566e;border-radius:4px;padding:8px 17px;cursor:pointer;font-size:14px}.filter-row button[aria-pressed=true]{background:#102d50;border-color:#102d50;color:#fff}.filter-row>span{font-size:13px;color:#64748b;margin-left:auto}.lesson-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:28px 24px}.lesson-card{border:1px solid #dce4ed;background:#fff;border-radius:6px;overflow:hidden;transition:box-shadow .2s,transform .2s}.lesson-card:hover{box-shadow:0 10px 25px #142e5010;transform:translateY(-3px)}.lesson-cover{display:block;position:relative;border-bottom:1px solid #e2e8f0}.lesson-cover img{width:100%;height:auto;aspect-ratio:4/3;object-fit:contain}.play-mark{position:absolute;left:14px;bottom:14px;background:#fffE;color:#102d50;border-radius:50%;width:34px;height:34px;display:grid;place-items:center;font-size:14px;padding-left:2px}.lesson-time{position:absolute;right:12px;bottom:12px;background:#102338e8;color:#fff;border-radius:3px;font-size:12px;padding:3px 8px}.lesson-copy{padding:22px}.lesson-copy .lesson-meta{min-height:0;font-size:11px;color:#0768d8;letter-spacing:1px;margin:0 0 10px}.lesson-copy h2{font-size:20px;line-height:1.5;min-height:60px;margin:0 0 10px}.lesson-copy>p{font-size:14px;line-height:1.85;color:#5f6c7e;min-height:78px;margin:0 0 18px}.lesson-link{display:flex;justify-content:space-between;color:#0768d8;font-size:14px;font-weight:700;border-top:1px solid #e3e9ef;padding-top:15px}.classroom-note{background:#f4f7fa;padding:26px 30px;margin-top:40px;border-left:3px solid #0768d8;color:#5d6c7e;font-size:14px}.classroom-note h2{color:#243b53;font-size:17px;margin:0 0 8px}.classroom-note a,.watch-reading a{display:inline-block;color:#0768d8;margin-right:22px}.empty-state{padding:50px;text-align:center;background:#f4f7fa;color:#5f6c7e}[hidden]{display:none!important}.watch-page{padding-top:28px}.watch-layout{display:grid;grid-template-columns:minmax(0,1fr) 300px;gap:42px}.watch-heading h1{text-wrap:balance;font-size:32px;margin:10px 0}.watch-heading>p:last-child{color:#627286;font-size:13px;margin:0 0 24px}.watch-heading .eyebrow{font-size:12px}.watch-stage{background:#122333;border-radius:7px;display:flex;justify-content:center;overflow:hidden}.watch-stage video{display:block;width:100%;height:min(70vh,720px);min-height:400px;object-fit:contain;background:#122333}.watch-stage video:focus-visible{outline:3px solid #0768d8;outline-offset:-3px}.watch-next{display:flex;gap:20px;justify-content:space-between;font-size:13px;color:#0768d8;padding:14px 0 24px;border-bottom:1px solid #d8e0ea}.watch-next a:last-child{text-align:right}.player-status{font-size:13px;color:#8d4212;min-height:0;margin:7px 0}.player-status:empty{display:none}.lesson-summary{padding:22px 0 12px}.watch-main h2{font-size:21px;margin:0 0 12px}.lesson-summary p,.chapter-section>p{font-size:15px;color:#52647a;line-height:1.9}.lesson-summary .lesson-context{font-size:13px;background:#f1f6fb;padding:14px 16px;border-left:2px solid #aec9e6}.chapter-section{padding:18px 0}.chapter-section>p{font-size:13px;margin-top:0}.chapters{list-style:none;padding:0;margin:0;border:1px solid #dce4ed;border-radius:5px;overflow:hidden}.chapters li+li{border-top:1px solid #e4ebf2}.chapters button{width:100%;display:flex;text-align:left;gap:20px;padding:13px 17px;background:#fff;border:0;color:#273f59;font-size:14px;cursor:pointer}.chapters button:hover{background:#edf4fb}.chapters time{font-variant-numeric:tabular-nums;color:#0768d8;flex:0 0 42px}.lesson-queue{align-self:start;border:1px solid #d9e3ed;border-radius:5px;margin-top:7px;background:#fff}.lesson-queue>h2{font-size:17px;margin:0;padding:20px;border-bottom:1px solid #d9e3ed}.lesson-queue>h2 span{float:right;color:#0768d8}.queue-item{display:flex;gap:12px;padding:15px 16px;border-bottom:1px solid #e6ecf3;font-size:13px;line-height:1.6}.queue-item>span{font-size:11px;color:#7a8ea3;padding-top:3px}.queue-item small{display:block;font-size:11px;color:#7a8ea3;margin-top:5px}.queue-item[aria-current=page]{background:#edf5ff;box-shadow:inset 3px 0 #0768d8;color:#0768d8;font-weight:700}.queue-item:hover{background:#f4f8fc}.lesson-queue>p{font-size:12px;color:#6a7d91;padding:10px 20px;line-height:1.9}.watch-reading{border-top:1px solid #d8e0ea;padding-top:25px;margin-top:16px;font-size:14px}.watch-reading a{margin-bottom:12px}button:focus-visible,a:focus-visible,input:focus-visible{outline:3px solid #63a7e7;outline-offset:3px}@media(max-width:1000px){.classroom-hero{gap:30px;grid-template-columns:1fr 250px}.lesson-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.watch-layout{grid-template-columns:minmax(0,1fr) 250px;gap:25px}.course-facts{gap:20px}}@media(max-width:700px){.classroom{padding:0 18px 44px}.classroom-hero{display:block;padding-top:26px}.classroom h1{font-size:32px}.hero-intro{font-size:15px}.teacher-intro{display:none}.course-facts{gap:18px}.course-facts strong{font-size:21px}.course-facts span{font-size:11px}.section-top{display:block}.lesson-search{margin-top:18px}.lesson-search input{width:100%}.lesson-grid{grid-template-columns:1fr;gap:22px}.lesson-copy h2{min-height:0}.lesson-copy>p{min-height:0}.classroom-note{padding:22px 19px}.filter-row{gap:6px}.filter-row button{padding:8px 11px;font-size:13px}.filter-row>span{font-size:12px}.watch-page{padding-top:24px}.watch-layout{display:block}.watch-heading h1{font-size:28px}.watch-stage video{height:66vh;min-height:340px;max-height:670px}.watch-next{font-size:12px}.lesson-queue{margin-top:35px}.chapters button{gap:12px}.crumb{margin-bottom:24px;font-size:12px}.classroom-note a{margin-top:10px}}@media(prefers-reduced-motion:reduce){.lesson-card{transition:none}.lesson-card:hover{transform:none}}