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@media(min-width:1550px){.workspace{padding:40px 48px}.exercise-layout{grid-template-columns:minmax(0,1fr) 285px}.card{padding:32px}}@media(max-width:1150px){.layout{grid-template-columns:245px minmax(0,1fr)}.workspace{padding:25px}.exercise-layout{grid-template-columns:1fr}.reference{display:none}.heading h2{font-size:30px}.coverage-grid{grid-template-columns:1fr 1fr}}@media(max-width:760px){.top{height:74px;padding:0 17px}.brand p{display:none}.mark{width:34px;height:36px;font-size:25px}.brand h1{font-size:23px}.language button{padding:8px 10px}.layout{display:block;min-height:calc(100vh - 74px)}.sidebar{display:none}.workspace{padding:20px 16px 30px}.mobile-topic{display:grid;grid-template-columns:minmax(0,1fr) 125px;gap:10px;margin-bottom:24px}.mobile-topic label{display:block;font-size:12px;margin-bottom:6px;color:var(--muted)}.context{align-items:flex-start;margin-bottom:18px}.crumb{font-size:12px}.session{font-size:12px}.heading h2{font-size:29px}.heading{gap:10px}.heading .badge{display:none}.intro{font-size:15px;margin-bottom:15px}.tabs{gap:20px;overflow:auto;white-space:nowrap;margin-bottom:18px}.tab{font-size:14px}.card{padding:20px 17px;border-radius:10px}.question-title{font-size:21px}.question-copy{font-size:16px}.question-picker{max-width:calc(100% - 96px)}.question-nav{gap:8px}.nav-buttons button{padding:9px 12px}.notes-grid{grid-template-columns:1fr}.coverage-grid{grid-template-columns:1fr}.question-count{font-size:12px}.data-table{font-size:14px}.data-table th,.data-table td{padding:9px 5px}.card-top{align-items:flex-start}.question-picker{font-size:13px}.bottom-note{font-size:12px}.mobile-bottom{display:block}.source-list{overflow-wrap:anywhere}.glossary td{font-size:14px}.input-wrap{flex-wrap:wrap}}@media(prefers-reduced-motion:no-preference){button{transition:background .15s,border-color .15s}.result{animation:enter .2s ease}@keyframes enter{from{opacity:0;transform:translateY(4px)}to{opacity:1;transform:translateY(0)}}}@media print{.top,.sidebar,.mobile-topic,.context,.tabs,.actions,.question-nav,.bottom-note,.language,.reference{display:none}.layout,.exercise-layout{display:block}.workspace{padding:0;max-width:none}.card{border:0;padding:0}.solution,.hint{break-inside:avoid}.notes-grid{display:block}.formula-card{break-inside:avoid;margin:10px 0}.answer-input{border:0;border-bottom:1px solid #333}body{background:white}}

.mobile-topic>div{min-width:0}.mobile-topic select{min-width:0;max-width:100%}

/* Chapter resources and supplementary exercise levels. */
.difficulty{display:inline-block;margin:0 0 16px;padding:5px 10px;border:1px solid #c7d9ec;border-radius:6px;background:#eef5fc;color:#23486c;font-size:.78rem;font-weight:700;letter-spacing:.02em}
.difficulty-challenge{background:#fff4e7;border-color:#e9cba4;color:#80501b}
.difficulty-easy{background:#eef7f1;border-color:#c0ddcb;color:#285b3c}
.solution li{white-space:pre-line}
.resource-list{list-style:none;padding:0;margin:18px 0 0;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px}
.resource-item{padding:18px;border:1px solid #dbe4ee;border-radius:9px;min-width:0;background:#fbfdff}
.resource-item a{color:#214f92;font-weight:700;text-decoration:underline;text-underline-offset:3px;overflow-wrap:anywhere}
.resource-item a:hover{color:#112847}.resource-item a:focus-visible{outline:3px solid #9abae9;outline-offset:4px}
.resource-meta{margin:9px 0;font-size:.76rem;line-height:1.6;color:#4c607a}
.resource-item p{font-size:.88rem;margin:8px 0 0;line-height:1.65}
.chapter-resources h4{margin:24px 0 0}.external-arrow{white-space:nowrap}
@media(max-width:650px){.resource-list{grid-template-columns:1fr}.resource-item{padding:15px}}