/* A lesson pairs a concrete construction with the reasoning that explains it. */
.lesson-intro{padding-bottom:25px}.lesson-intro #lesson-deck{max-width:820px;font-size:17px;color:#b6cbc7}.concept-tools{display:flex;align-items:center;gap:17px;flex-wrap:wrap;margin-top:22px}.concept-tools>span{font-size:12px;color:#8fa6a4}#concept-buttons{display:flex;gap:8px;flex-wrap:wrap}#concept-buttons button{font-size:12px;line-height:1.4;padding:8px 11px;border:1px solid #344940;border-radius:5px;color:#bfd5ca;text-align:left}#concept-buttons button span{margin-left:8px;color:#87b69e}#concept-buttons button[aria-expanded=true]{background:#253c32;border-color:#8eae9d}#concept-definition{max-width:880px;margin-top:14px;padding:16px 19px;border-left:2px solid #b8e7c9;background:#16242a;font-size:15px;line-height:1.8;color:#b5c7d0}#concept-definition strong{color:#d5ecdc;margin-right:8px}.lesson-layout{grid-template-columns:155px minmax(260px,.85fr) minmax(350px,1.15fr);gap:22px 32px;padding-top:28px;align-items:start}.chapter-nav{grid-column:1;grid-row:1/3;top:100px}.chapter-heading{grid-column:2/4;grid-row:1;max-width:920px}.chapter-heading h2{font:38px/1.2 var(--serif);margin:12px 0;color:#eef2e9}.chapter-heading>p{font-size:19px;line-height:1.6;color:#b8e7c9;margin:0;max-width:820px}.chapter-reading{grid-column:2;grid-row:2}.chapter-reading>.eyebrow{font-size:9px;line-height:1.6;letter-spacing:1.4px;margin:5px 0 14px}#chapter-body p{font-size:16px;line-height:1.85;color:#becdd1;margin:0 0 17px}.worked-example{margin:22px 0;padding:18px 0 0}.worked-example p{font-size:15px;line-height:1.9;margin:13px 0}.lesson-visual{grid-column:3;grid-row:2;position:sticky;top:98px;width:100%}.lesson-stage{height:auto;aspect-ratio:560/330;min-height:240px}.lesson-stage canvas{position:absolute;inset:0}.lesson-figure-heading{padding:15px 18px;letter-spacing:0;font-size:12px;line-height:1.5;text-transform:none}.lesson-figure-heading>span{color:#c4d5cc}#foundation-board{height:100%;width:100%;position:absolute;inset:0}#foundation-board svg{display:block;width:100%;height:100%}.construction-controls{padding:13px 18px 0;border-top:1px solid #24352e}.construction-scrubber{display:flex;gap:13px;align-items:center}.construction-scrubber button{width:34px;height:34px;flex-shrink:0;border:1px solid #445e50;border-radius:6px;color:#b8e7c9;font-size:21px;background:#1a2b28;line-height:1}.construction-scrubber button:disabled{opacity:.3;cursor:default}.construction-scrubber input{width:100%;min-width:0;flex:1}#construction-count{display:block;white-space:normal;font-size:10px;color:#92aea0;line-height:1.7;margin-top:9px}#foundation-preset{display:block;margin:0 0 12px;width:100%;padding:8px 10px;background:#1c2c34;border:1px solid #3d534b;border-radius:5px;color:#c3d9cc;font-size:12px}.lesson-figure-caption{padding:13px 18px 0;font-size:14px;line-height:1.75;color:#bdcfd2;min-height:0}.notice-box{margin:17px 18px 0;padding:13px 15px;background:#201f32;border-left:2px solid #c5a7ef}.notice-box>span{font:9px var(--mono);letter-spacing:1px;color:#c5a7ef}.notice-box p{font-size:13px;line-height:1.7;color:#cbc4dc;margin:7px 0 0}.lesson-progress{padding:16px 18px}.lesson-progress>span{font-size:9px}.lesson-progress>div{margin-top:9px}.lesson-visual>a{font-size:12px;padding:13px 18px}.prediction-panel{display:grid;grid-template-columns:1fr 1fr;gap:45px;padding:30px;border:1px solid #3b454d;border-radius:12px;background:linear-gradient(125deg,#17262c,#1a1d2c);margin:0 0 32px}.prediction-panel .eyebrow{color:#c5a7ef;font-size:10px}.prediction-panel h2{font-size:30px;line-height:1.25;margin:15px 0}.prediction-panel>div>p{font-size:14px;line-height:1.75;color:#94abb2;margin:0;max-width:500px}#prediction-choices{display:grid;gap:9px}#prediction-choices button{border:1px solid #3c4c57;border-radius:6px;padding:13px;text-align:left;font-size:14px;line-height:1.5;display:flex;gap:12px;align-items:center;color:#c1d0d6}#prediction-choices button>span{font:11px var(--mono);color:#9eacc1;border:1px solid #42505e;padding:4px 6px;border-radius:3px;flex-shrink:0}#prediction-choices button:hover{background:#25313e}#prediction-choices .answer-correct{border-color:#9fd6b3;background:#20372e}#prediction-choices .answer-rethink{border-color:#c4a081;background:#332b25}#prediction-feedback{margin-top:17px!important;padding:14px 16px;border-radius:6px;color:#d3ddd5!important;background:#1e342b;max-width:none!important}#prediction-feedback.rethink{background:#332b25}.chapter-controls{margin-top:25px}.chapter-controls button{min-height:44px}.lesson-takeaway h2{font-size:32px}.lesson-references{font-size:13px}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible{outline:2px solid #c5a7ef;outline-offset:4px}
@media(max-width:1200px){.lesson-layout{grid-template-columns:140px minmax(0,1fr);gap:24px}.chapter-nav{grid-row:1/4}.chapter-heading{grid-column:2;grid-row:1}.lesson-visual{grid-column:2;grid-row:2;position:static;max-width:760px}.chapter-reading{grid-column:2;grid-row:3;max-width:760px}.chapter-heading h2{font-size:35px}.chapter-reading .worked-example{margin-bottom:10px}}
@media(max-width:700px){.lesson-intro #lesson-deck{font-size:15px;line-height:1.7}.concept-tools{margin-top:20px;gap:10px}.concept-tools>span{font-size:11px;width:100%}#concept-buttons{gap:6px}#concept-buttons button{font-size:11px;padding:7px 9px}#concept-definition{font-size:14px;padding:13px 15px}.lesson-layout{grid-template-columns:minmax(0,1fr);gap:20px;padding-top:20px}.chapter-nav{grid-column:1;grid-row:1;min-width:0}.chapter-heading{grid-column:1;grid-row:2}.chapter-heading h2{font-size:31px}.chapter-heading>p{font-size:17px;line-height:1.65}.chapter-count{font-size:10px}.lesson-visual{grid-column:1;grid-row:3;order:0}.chapter-reading{grid-column:1;grid-row:4;order:0}#chapters button{min-width:138px;max-width:175px;font-size:11px}.lesson-stage{min-height:210px}.lesson-figure-heading{padding:12px 14px;font-size:12px}.construction-controls{padding:12px 14px 0}.lesson-figure-caption{padding:12px 14px 0;font-size:13px}.construction-scrubber button{width:38px;height:38px}.notice-box{margin:14px 14px 0}.lesson-progress{padding:14px}.lesson-visual>a{padding:12px 14px}.chapter-reading>.eyebrow{margin-top:5px}#chapter-body p{font-size:15px;line-height:1.85}.prediction-panel{grid-template-columns:minmax(0,1fr);gap:22px;padding:23px 19px}.prediction-panel h2{font-size:28px}#prediction-choices button{font-size:14px}.prediction-panel>div>p{font-size:13px}.chapter-controls{margin-top:20px}.lesson-takeaway h2{font-size:29px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important}}