/* Theme and typography choices extend, rather than replace, the user's reading components. */
html[data-reading="slate"] body{--bg:#111827;--paper:#192336;--side:#0f1726;--ink:#e8edf5;--muted:#b7c5d9;--accent:#a6d5ff;--soft:#25354b;--line:#41516a;--gold:#f6d48a;--code:#203047;color-scheme:dark;background-image:none}
html[data-reading="forest"] body{--bg:#0f1c17;--paper:#172b22;--side:#102119;--ink:#eaf2e8;--muted:#b3ccba;--accent:#ade2b3;--soft:#253e2d;--line:#45604b;--gold:#ead794;--code:#20382a;color-scheme:dark;background-image:none}
html[data-reading="contrast"] body{--bg:#fff;--paper:#fff;--side:#fff;--ink:#080808;--muted:#252525;--accent:#003b80;--soft:#edf3fc;--line:#606060;--gold:#5d3000;--code:#f1f1f1;--shadow:none;color-scheme:light;background-image:none}
:root{--reading-size:19px;--reading-leading:1.8;--reading-width:44rem}
body{font-size:var(--reading-size);line-height:var(--reading-leading);letter-spacing:0}
main,.reading-sample{font-size:var(--reading-size);line-height:var(--reading-leading)}
html[data-font="sans"] body{font-family:ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif}
main{width:100%;max-width:var(--reading-width);min-width:0}
.reading-layout{grid-template-columns:minmax(0,var(--reading-width)) 12rem;justify-content:center;gap:2rem}
main p,main>p,main .intro,main .callout p,main details.proof,main .exercise details p,main .callout-body,main .lesson-detail{font-size:1em;line-height:var(--reading-leading)}
main li{line-height:var(--reading-leading)}main textarea{font:inherit;line-height:1.6}main input,main select,main button{font-size:max(16px,.85em)}main table{font-size:.9em;line-height:1.6}.katex{font-size:1.08em}
main .meta,main .muted,main small,main .prereqs,main .rubric{font-size:max(14px,.78em)}
main pre{font-size:max(14px,.8em);line-height:1.65}main h2{font-size:1.5em;line-height:1.3}main h3{font-size:1.15em;line-height:1.4}
#reading-dialog{max-width:580px;width:calc(100% - 2rem);max-height:85vh;overflow:auto;background:var(--paper);color:var(--ink);border:1px solid var(--line);border-radius:12px;padding:1.5rem}
dialog::backdrop{background:#10182099}.reading-options{display:grid;grid-template-columns:1fr 1fr;gap:1rem}.reading-options label{display:grid;gap:.4rem;font:500 15px/1.5 system-ui}.reading-options select{min-height:44px;color:var(--ink);background:var(--paper)}.reading-sample{padding:1rem;border:1px solid var(--line);border-radius:8px;margin:1rem 0}
.reading-focus .sidebar,.reading-focus .on-page{display:none}.reading-focus .workspace{margin-left:0}.reading-focus .reading-layout{grid-template-columns:minmax(0,var(--reading-width))}
.guided-link{background:var(--soft);font-weight:700;border:1px solid var(--line);margin-bottom:1rem!important}.lesson-chapter-link{display:flex;align-items:center;gap:1rem;flex-wrap:wrap;margin:1.5rem 0}.lesson-chapter-link span{font:14px/1.5 system-ui;color:var(--muted)}
.lesson-mode-nav{display:flex;justify-content:space-between;gap:1rem;flex-wrap:wrap;font:14px/1.6 system-ui;margin:1.5rem 0}.lesson-steps{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:.6rem;margin:1.5rem 0 2rem}.lesson-steps a{display:flex;gap:.5rem;align-items:center;border:1px solid var(--line);padding:.7rem;border-radius:8px;text-decoration:none;font:500 14px/1.4 system-ui}.lesson-steps a[aria-current]{border-color:var(--accent);background:var(--soft);box-shadow:inset 0 -3px var(--accent)}.lesson-steps span{width:24px;height:24px;border-radius:50%;display:grid;place-items:center;background:var(--side);flex-shrink:0}
.lesson-concept h2{padding-top:0;margin-top:1rem}.lesson-example{border:1px solid var(--line);border-left:4px solid var(--accent);padding:1.4rem;margin:1.5rem 0;border-radius:8px;background:var(--paper)}.lesson-example h3{margin-top:.5rem}.example-check{border-top:1px solid var(--line);padding-top:1rem;color:var(--muted);font-size:.85em!important}.lesson-detail{border:1px solid var(--line);padding:1rem;border-radius:8px;margin:1rem 0;background:var(--paper)}.lesson-detail>summary{cursor:pointer;color:var(--accent);font:600 15px/1.6 system-ui}.lesson-detail details{margin:1rem 0}.lesson-detail summary{min-height:30px}
.prerequisite-note{padding:1rem;background:var(--soft);border:1px solid var(--line);border-radius:8px;font-size:.85em}.prerequisite-note summary{cursor:pointer;font-weight:600}.practice-checkpoint{border-top:2px solid var(--line);margin-top:2rem}.practice-prompt{font-weight:600}.answer-row{display:flex;gap:.6rem;flex-wrap:wrap;margin:.5rem 0}.answer-row input{min-width:0;flex:1 1 180px;min-height:46px;background:var(--paper);color:var(--ink);border:1px solid var(--line);border-radius:6px;padding:.7rem;font:inherit}.practice-checkpoint small{display:block;color:var(--muted);font:14px/1.5 system-ui}.practice-checkpoint label,.lesson-reasoning>label{font:600 15px/1.5 system-ui}.practice-hint{margin:1rem 0}.practice-hint summary{cursor:pointer;color:var(--accent)}.answer-feedback{border:1px solid var(--line);border-left:4px solid var(--gold);padding:1rem;background:var(--paper);border-radius:6px;margin:1rem 0}.answer-feedback.is-correct{border-left-color:var(--accent)}.answer-feedback p:last-child{font-size:.85em!important}.practice-next{margin:.5rem 0}.practice-next[hidden]{display:none}.lesson-bottom{display:flex;justify-content:space-between;align-items:center;gap:1rem;margin-top:2rem}.lesson-reasoning textarea{width:100%;padding:1rem;background:var(--paper);color:var(--ink);border:1px solid var(--line);border-radius:8px}.lesson-finish{border-top:1px solid var(--line);margin-top:2rem}.lesson-row{display:flex;gap:1rem;align-items:center;padding:1.2rem 0;border-bottom:1px solid var(--line)}.lesson-row>div{flex:1;min-width:0}.lesson-row h3{margin:0}.lesson-row p{margin:.3rem 0;font-size:.85em!important}.lesson-row small{color:var(--muted);font:13px/1.5 system-ui}.lesson-number{color:var(--muted);font:500 17px/1.5 system-ui}.lesson-row .button{white-space:nowrap}
.toolbar{flex-wrap:wrap;gap:.4rem}.toolbar>div{flex-wrap:wrap}.toolbar select,.toolbar button{min-height:40px}.toolbar #breadcrumb{max-width:38vw;overflow:hidden;white-space:nowrap;text-overflow:ellipsis}
@media(max-width:1250px){.on-page{display:none}.reading-layout{grid-template-columns:minmax(0,var(--reading-width));padding:2rem 1.5rem}}
@media(max-width:850px){.reading-layout{padding:1.4rem 1rem}.toolbar #breadcrumb{max-width:36vw}.reading-focus .sidebar{display:none}}
@media(max-width:520px){.lesson-steps{gap:.3rem}.lesson-steps a{font-size:12px;padding:.5rem;flex-direction:column;align-items:flex-start}.lesson-example{padding:1rem}.lesson-row{gap:.6rem;flex-wrap:wrap}.lesson-row .button{font-size:13px;padding:.4rem .6rem}.reading-options{grid-template-columns:1fr}.lesson-bottom{flex-wrap:wrap}.toolbar #breadcrumb{display:none}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}
@media print{.lesson-mode-nav,.lesson-steps,.practice-checkpoint form,.practice-next,#reading-dialog{display:none!important}body,main{font-size:11pt!important;line-height:1.5!important}.reading-layout{display:block}}
.lesson-figure{margin:1.5rem 0;padding:1rem;background:var(--paper);border:1px solid var(--line);border-radius:8px}.lesson-figure svg{display:block;width:100%;max-height:230px;color:var(--ink);font:14px system-ui}.lesson-figure figcaption{font:14px/1.6 system-ui;color:var(--muted);padding-top:.6rem}.reading-focus #menu{display:none}