.fractions-hero{position:relative;min-height:450px;display:flex;align-items:end;isolation:isolate;border-bottom:1px solid #d1aa5244}.fractions-hero>img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;object-position:50% 35%;z-index:-2}.fractions-hero:after{content:'';position:absolute;inset:0;background:linear-gradient(90deg,#06131fe8,#06131f35),linear-gradient(0deg,#06131ff0,transparent);z-index:-1}.fractions-hero .wrap{padding-block:55px}.fractions-hero h1{font-size:clamp(54px,7vw,100px);margin:18px 0}.fractions-hero p{font-size:20px;max-width:550px}.course{display:grid;grid-template-columns:250px minmax(0,1fr);gap:42px;padding-block:50px 80px;align-items:start}.course-nav{position:sticky;top:115px}.course-nav>p{font-size:12px;letter-spacing:1px;color:var(--gold);margin-bottom:16px}.lesson-button{display:flex;gap:12px;width:100%;text-align:left;background:transparent;border:0;border-bottom:1px solid #a9bac522;padding:16px 12px;font:inherit;font-size:15px;color:var(--muted);line-height:1.4;cursor:pointer}.lesson-button span{color:var(--gold);font-size:12px;min-width:20px}.lesson-button[aria-current=step]{color:var(--ivory);background:#d1aa5218;border-left:3px solid var(--gold)}.course button:focus-visible,.course input:focus-visible,.course select:focus-visible{outline:3px solid #d1aa52;outline-offset:3px}.lesson-card{border:1px solid #d1aa5244;min-width:0;background:#0a1e2e}.lesson-copy{padding:38px 40px 28px}.lesson-copy h2{font-size:clamp(32px,3.6vw,52px);line-height:1.15;margin:14px 0 20px;scroll-margin-top:110px}.lesson-copy>p{max-width:740px;color:var(--muted);font-size:18px}.rule-box{border-left:3px solid var(--gold);padding:15px 20px;margin-top:24px;background:#d1aa520b;font-size:17px;line-height:1.65}.lesson-controls{padding:24px 40px;background:#06131f99;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}.input-group{border:1px solid #a9bac52d;padding:18px;min-width:0}.input-group legend{color:var(--gold);font-size:13px;padding:0 8px}.input-pair{display:flex;gap:18px;flex-wrap:wrap}.course label{display:flex;flex-direction:column;gap:9px;font-size:13px;color:var(--muted);min-width:0;flex:1}.course input,.course select{width:100%;min-width:75px;min-height:48px;border:1px solid #a9bac566;background:#102b3f;color:var(--ivory);font:inherit;font-size:21px;padding:10px;border-radius:0}.course select{font-size:17px}.lesson-result{padding:32px 40px 38px;min-height:220px}.big-equation{display:flex;align-items:center;justify-content:center;gap:18px;flex-wrap:wrap;font-family:Georgia,serif;font-size:clamp(28px,3vw,40px);line-height:1.7;margin:10px 0 25px}.fraction{display:inline-flex;flex-direction:column;vertical-align:middle;text-align:center;line-height:1.05;min-width:1.15em;margin:0 .12em;font-variant-numeric:tabular-nums}.fraction>span{padding:.13em .17em}.fraction>span+span{border-top:2px solid currentColor}.fraction.gold{color:var(--gold)}.lesson-result p{font-size:18px;line-height:1.75;margin:16px 0;color:var(--ivory)}.lesson-result .muted{color:var(--muted);font-size:15px}.worked-steps{padding-left:24px;font-size:18px;line-height:1.9;margin:20px 0}.worked-steps li{margin:10px 0}.visual-rows{display:grid;gap:18px;margin:24px 0}.unit-label{font-size:12px;color:var(--muted);margin-bottom:8px}.unit-bars{display:grid;grid-template-columns:repeat(auto-fit,minmax(145px,1fr));gap:12px}.unit-bar{display:flex;min-height:36px;border:1px solid #d1aa5266;background:#06131f;overflow:hidden}.unit-bar i{flex:1;border-right:1px solid #06131f70;min-width:0;background:#a9bac51d}.unit-bar i.filled{background:var(--gold)}.unit-bar.cyan i.filled{background:#6bcbdc}.visual-note{font-size:13px!important;color:var(--muted)!important}.answer-box{padding:20px 24px;background:#d1aa5210;border:1px solid #d1aa5244;margin-top:24px}.answer-box strong{color:var(--gold)}.euclid{font-family:monospace;line-height:1.9;padding:16px;background:#06131f;overflow-wrap:anywhere;font-size:16px}.course-pager{display:flex;justify-content:space-between;gap:15px;padding:26px 0}.course-pager button,.course-reset{font:inherit;min-height:46px;background:transparent;border:1px solid #d1aa5266;color:var(--ivory);padding:12px 18px;cursor:pointer}.course-pager button:disabled{opacity:.35;cursor:default}.course-reset{font-size:13px;margin-top:20px}.course-progress{font-size:13px;color:var(--muted);padding-top:16px}.course-status{padding:18px;border:1px solid #d1aa52;color:var(--gold)}.fraction-footer{border-top:1px solid #d1aa5244;padding:30px 0 55px;font-size:17px;line-height:1.8}.visually-hidden{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.cross-rule{color:var(--gold)}
@media(max-width:1050px){.course{grid-template-columns:210px minmax(0,1fr);gap:25px}.lesson-copy,.lesson-result{padding:28px}.lesson-controls{padding:24px;gap:16px;grid-template-columns:1fr}.input-pair label{min-width:95px}}
@media(max-width:700px){.fractions-hero{min-height:370px}.fractions-hero .wrap{padding-block:35px}.fractions-hero>img{object-position:57% center}.fractions-hero p{font-size:17px}.course{display:block;padding-top:25px}.course-nav{position:static;margin-bottom:22px}.lesson-list{display:flex;overflow-x:auto;gap:8px;padding-bottom:12px}.lesson-button{flex:0 0 175px;border:1px solid #a9bac533;padding:13px 10px;align-items:center;font-size:13px}.lesson-copy,.lesson-result{padding:24px 20px}.lesson-controls{padding:20px}.lesson-copy>p,.lesson-result p,.worked-steps{font-size:17px}.big-equation{gap:12px;font-size:29px}.rule-box{padding:14px;font-size:16px}.course-pager{gap:10px;flex-wrap:wrap}.course-progress{order:3;flex-basis:100%;text-align:center}.unit-bars{grid-template-columns:repeat(auto-fit,minmax(125px,1fr))}.lesson-card{scroll-margin-top:90px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}

.range-hint{font-size:12px;color:var(--muted);line-height:1.4}