.chapter-heading{display:flex;justify-content:space-between;gap:30px;align-items:center}.chapter-heading h1{font-size:clamp(2.6rem,4.2vw,4.2rem)}.chapter-heading .lede{max-width:800px}.chapter-tabs{display:flex;gap:26px;border-bottom:1px solid var(--line);margin:12px 0 32px;flex-wrap:wrap}.chapter-tabs a{padding:12px 0;text-decoration:none;font-size:15px;border-bottom:3px solid transparent}.chapter-tabs a[aria-current]{border-color:var(--red);color:var(--red);font-weight:600}.chapter-overview{display:grid;grid-template-columns:minmax(0,1.2fr) minmax(0,1fr);gap:60px;align-items:start}.chapter-introduction{font-size:19px}.chapter-overview .prose h2:first-of-type{margin-top:28px}.chapter-route{background:var(--wash);padding:26px;border:1px solid var(--line)}.chapter-route h2{font-size:2rem;margin-bottom:24px}.chapter-route>div{border-top:1px solid var(--line);padding:17px 0}.chapter-route p{font-size:15px;margin:9px 0}.chapter-route small{color:var(--muted);font-size:14px}.chapter-note{font-size:14px;color:var(--muted);margin:12px 0 20px;line-height:1.65}.chapter-resource-list{display:grid;grid-template-columns:1fr 1fr;gap:36px 48px;margin:42px 0}.chapter-resource-list h2{font-size:2.3rem;margin:0 0 18px}.chapter-resource-list a{display:flex;justify-content:space-between;gap:20px;padding:17px 0;border-top:1px solid var(--line);text-decoration:none}.chapter-resource-list a:hover span{color:var(--red)}.chapter-resource-list small{font-size:13px;color:var(--muted);text-align:right;min-width:100px}.chapter-sources{margin-top:35px}.chapter-instructions{max-width:1000px;margin:0 0 30px;font-size:16px;line-height:1.8}.chapter-set-picker{gap:8px;background:none;border:none;padding:0;flex-wrap:wrap}.chapter-set-picker .active{color:white;background:var(--ink);border-color:var(--ink)}.chapter-page .case-grid a{display:flex;position:relative;justify-content:center;text-decoration:none;padding:7px 0;border:1px solid #8a958c;font-size:14px;border-radius:2px}.chapter-page .case-grid a.current{outline:2px solid var(--red);outline-offset:1px}.chapter-page .case-grid a.correct{background:#e4eee8}.chapter-page .case-grid a.incorrect{background:#fde7e7}.chapter-page .case-grid a span{position:absolute;right:1px;bottom:-1px;font-size:10px}.chapter-item-nav{display:flex;flex-direction:column;gap:5px;margin:20px 0}.chapter-item-nav a{display:flex;gap:12px;padding:9px 10px;text-decoration:none;font-size:14px;line-height:1.6}.chapter-item-nav a>span{color:var(--muted);min-width:18px}.chapter-item-nav a[aria-current]{background:var(--tint);color:var(--red)}.chapter-extension{margin-top:28px;border-top:2px solid var(--line);padding-top:6px}.investigation-stage{border-top:1px solid var(--line);padding-top:10px;margin-top:28px}.chapter-page .prose h2.generation-title{margin:18px 0 22px}.chapter-page .question-prompt{font-size:1.15rem}.station-chapters{grid-template-columns:repeat(4,minmax(0,1fr))}.station-chapters .resource-card{min-height:270px}.station-chapters .resource-card h3{font-size:1.85rem}.station-summary{display:flex;gap:24px;flex-wrap:wrap;font-size:14px;color:var(--muted);margin:24px 0}.station-coverage{margin-top:36px}.station-coverage h2{font-size:2rem;margin-bottom:16px}.chapter-page,.chapter-page *{min-width:0}.chapter-page .katex-display{overflow-x:auto;max-width:100%}.chapter-page .question-card{overflow-wrap:break-word}.chapter-page .question-card .katex{overflow-wrap:normal}.print-sheet .print-question{font-family:var(--sans)}
@media(max-width:1000px){.station-chapters{grid-template-columns:repeat(2,minmax(0,1fr))}.chapter-overview{gap:30px}}
@media(max-width:680px){.chapter-heading{display:block}.chapter-heading>.secondary{margin-bottom:16px}.chapter-tabs{gap:6px 19px;margin-top:16px}.chapter-tabs a{padding:10px 0;font-size:14px}.chapter-overview,.chapter-resource-list,.station-chapters{grid-template-columns:1fr}.chapter-route{padding:20px}.chapter-resource-list{gap:28px}.chapter-resource-list a{font-size:15px}.chapter-item-nav{display:grid;grid-template-columns:1fr 1fr}.chapter-item-nav a{padding:8px;font-size:13px}.chapter-page .question-prompt{font-size:1.04rem}.chapter-page .choice-row button{overflow-wrap:normal}.chapter-page .question-card{padding:22px 17px}.station-chapters .resource-card{min-height:210px}}
@media print{.chapter-tabs,.chapter-heading>.secondary{display:none}.print-sheet .katex-display{overflow:visible}.print-sheet .chapter-note{font-size:10pt}}

.teacher-chapter-links{display:flex;flex-wrap:wrap;gap:10px;margin:0 0 32px;padding:20px;background:var(--wash);border:1px solid var(--line)}.teacher-chapter-links>.resource-type{width:100%;margin-bottom:6px}

.chapter-diagram{max-width:560px;margin:24px auto;background:var(--wash);border:1px solid var(--line);padding:18px;break-inside:avoid}.chapter-diagram svg{width:100%;height:auto}.chapter-diagram figcaption{font-size:14px;line-height:1.7;color:var(--muted)}.diagram-label{font-size:14px;line-height:1.4;color:var(--ink)}

.brand{gap:12px;font-size:23px;font-weight:600;letter-spacing:-.75px;line-height:1.1;white-space:nowrap}.brand-symbol{display:block;width:56px;height:54px;mask:none;-webkit-mask:none;background:none;padding:0}.brand-mark-large{width:125px;height:120px;mask:none;-webkit-mask:none;background:transparent url('overground-symbol.svg') center/contain no-repeat}.brand-wordmark{display:block}
@media(max-width:680px){.brand{font-size:22px;gap:11px}.brand-symbol{width:48px;height:47px}}

main:focus,.chapter-page .question-card:focus{outline:none}