:root{--paper:#f7f6f0;--ink:#203638;--muted:#536c70;--teal:#176c64;--blue:#245dac;--amber:#a45612;--line:#ccd8d7;--wash:#eaf2ef;--white:#fff;--center:#176c64;font-family:Segoe UI,system-ui,sans-serif;color:var(--ink);background:var(--paper);font-synthesis:none}
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@media(max-width:480px){main{padding:18px 14px}.site-header{padding:14px 14px 0}.brand-mark{font-size:28px}.brand p{font-size:14px}.brand p span{font-size:11px}.utilities{margin:0;width:100%;justify-content:flex-end}.site-header{gap:8px}nav{gap:3px}nav button{font-size:12px;padding:7px 9px;min-height:40px}nav small{margin-right:5px}.choices button{padding:9px 12px;font-size:13px}.reasoning,.geometry{padding:18px}.geometry-header h2{font-size:18px}.tag{display:none}.graph-caption{font-size:12px}.action{padding:14px}.action p{font-size:14px}.lesson-controls{padding:14px;display:block}.advance{margin:12px 0}.advance .primary{flex:1;min-width:0}.motion-controls{justify-content:space-between}.footnote{padding:14px}.check-panel{padding:18px}.branch{gap:5px}.branch .math{font-size:21px}.math{font-size:25px}.hero-math{font-size:34px}.takeaway{font-size:15px}.practice{padding:14px}.practice select{width:100%;margin:6px 0 12px}}
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.probe-ring{fill:none}
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@media(max-width:1150px){.board{grid-template-columns:1fr}.reasoning{border-right:0;border-bottom:1px solid var(--line)}.geometry{width:100%}.reasoning .algebra{max-width:650px}.reasoning .branch-grid{max-width:650px}.reasoning .all-parts{font-size:23px}.reasoning .branch-grid .all-parts{font-size:20px}.graph-scroll svg{max-width:820px;margin:auto}.fact-row{max-width:500px}.answer-grid .all-parts{font-size:18px}.answer-grid .branch-grid{display:block}.answer-grid .branch-grid>.join{display:block;margin:12px 0}.lesson-controls{flex-wrap:wrap}.motion-controls{margin-left:auto}}
@media(max-width:800px){.bridge{grid-template-columns:1fr;gap:15px}.roadmap{gap:15px}.roadmap h2{font-size:17px}.roadmap p{font-size:14px}.answer-grid{grid-template-columns:1fr}.answer-grid>div:nth-child(odd){border-right:0}.answer-grid>div+div{border-top:1px solid var(--line)}.answer-grid .branch-grid{display:grid}.answer-grid .branch-grid>.join{margin:10px 0 0}.paper-gate{grid-template-columns:1fr;gap:0}.paper-emblem{display:none}.parts li{font-size:12px;padding:10px}.brand p span{font-size:11px}.lesson-controls{position:static}.advance .primary{min-width:190px}.aleks-grid{grid-template-columns:1fr}}
@media(max-width:480px){.roadmap{grid-template-columns:1fr;gap:20px}.opening h1{font-size:38px}.opening-lead{font-size:17px}.bridge{padding:20px}.parts{gap:4px}.parts li{padding:8px 5px;font-size:11px;text-align:center}.parts b{display:block;margin:0 0 4px}.reasoning .all-parts{font-size:18px}.reasoning .branch-grid{display:block}.reasoning .branch-grid>.join{display:block;margin:15px 0}.answer-grid .branch-grid{display:block}.reasoning .branch-grid .all-parts{font-size:21px}.answer-grid>div{padding:20px}.answer-grid .all-parts{font-size:17px}.interpretation{font-size:19px}.paper-gate{padding:20px}.paper-gate .primary{font-size:14px;width:100%}.hero-math{font-size:32px}.geometry-header h2{font-size:17px}.check-result .math{font-size:20px}.motion-controls{justify-content:flex-end;gap:8px}}