.lesson-app{background:var(--app-bg);min-height:100vh}.lesson-page{width:min(1100px,100% - 40px);margin:auto;padding:34px 0 80px}.lesson-back{color:var(--muted);font-size:12px}.lesson-layout{grid-template-columns:minmax(0,760px) 250px;gap:28px;margin-top:18px;display:grid}.lesson-layout>article{border:1px solid var(--line);background:var(--surface);border-radius:9px;padding:32px}.lesson-layout article>header p{color:var(--gold);text-transform:uppercase;margin:0 0 9px;font-size:11px;font-weight:750}.lesson-layout article>header h1{letter-spacing:-.03em;margin:0;font-size:38px}.lesson-layout article>header span{color:var(--muted);margin-top:8px;display:block}.lesson-objective{border-left:3px solid var(--gold);background:var(--surface-2);margin:24px 0;padding:16px}.lesson-objective small,.lesson-rail small{color:var(--muted);font-size:9px;display:block}.lesson-objective strong{margin-top:6px;display:block}.lesson-body{font-size:16px;line-height:1.75}.lesson-body h2{margin:30px 0 8px;font-size:24px}.lesson-body p{color:var(--ink)}.lesson-body .lesson-callout,.lesson-body>aside{border:1px solid var(--line);background:var(--surface-2);border-radius:6px;margin:22px 0;padding:16px}.lesson-body img{max-width:100%;height:auto}.lesson-layout article>footer{border-top:1px solid var(--line);align-items:center;gap:14px;margin-top:30px;padding-top:20px;display:flex}.lesson-layout article>footer button{background:var(--gold);border:0;border-radius:6px;padding:11px 14px;font-weight:750}.lesson-layout article>footer span{color:var(--muted);font-size:12px}.lesson-rail{border:1px solid var(--line);background:var(--surface);border-radius:8px;align-self:start;position:sticky;top:90px}.lesson-rail>div,.lesson-rail a{border-bottom:1px solid var(--line);padding:16px;display:block}.lesson-rail nav a:last-child{border:0}.lesson-rail strong,.lesson-rail span{margin-top:5px;display:block}.lesson-rail span{color:var(--muted);font-size:11px}@media (max-width:800px){.lesson-page{width:calc(100% - 24px)}.lesson-layout{grid-template-columns:1fr}.lesson-rail{order:-1;position:static}.lesson-layout>article{padding:22px}.lesson-layout article>header h1{font-size:31px}}