:root{color-scheme:light;--ink:#17212b;--muted:#64748b;--paper:#fbfaf6;--accent:#0f766e;--line:#d9d5ca}*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font:18px/1.65 ui-serif,Georgia,serif}.lesson,.course{max-width:780px;margin:0 auto;padding:clamp(28px,7vw,80px) 24px 100px}h1,h2,h3{font-family:ui-sans-serif,system-ui,sans-serif;line-height:1.15;letter-spacing:-.025em}h1{font-size:clamp(2.2rem,7vw,4.8rem);margin:.3em 0}h2{margin-top:2.2em}a{color:var(--accent)}blockquote{border-left:4px solid var(--accent);margin:2rem 0;padding:.3rem 1.4rem;color:#334155}pre,code{font-family:ui-monospace,monospace}pre{overflow:auto;background:#10212a;color:#ecfeff;padding:1rem;border-radius:10px}details{border-block:1px solid var(--line);padding:1rem 0;margin:1.5rem 0}summary{cursor:pointer;font-family:ui-sans-serif,system-ui,sans-serif;font-weight:700}.eyebrow{color:var(--accent);font:700 .78rem/1.2 ui-sans-serif,system-ui,sans-serif;text-transform:uppercase;letter-spacing:.14em}.lesson-list{padding:0;list-style:none}.lesson-list li{border-top:1px solid var(--line);padding:1rem 0}.lesson-list a{font:700 1.1rem/1.3 ui-sans-serif,system-ui,sans-serif;text-decoration:none}img{max-width:100%;height:auto}button,input{font:inherit}@media print{body{background:#fff}.lesson{max-width:none;padding:0}a{color:inherit;text-decoration:none}}