*{box-sizing:border-box}body{margin:0;background:#f7f7f2;color:#243d30;font:16px/1.7 system-ui,sans-serif}header,footer{padding:30px max(24px,calc((100vw - 1200px)/2));background:#e9eee6}header span{font-size:11px;letter-spacing:2px}h1,h2{font-family:Georgia,serif;font-weight:400}h1{font-size:38px;margin:12px 0}main{display:grid;grid-template-columns:270px minmax(0,1fr);gap:40px;max-width:1200px;margin:35px auto;padding:0 24px}aside h2{font:13px system-ui}nav button{display:block;width:100%;text-align:left;background:transparent;border:0;border-radius:6px;padding:13px;color:inherit;cursor:pointer}nav button[aria-current=step]{background:#d9e5d2}audio,video{width:100%;margin:15px 0}video{border-radius:8px;background:#0d1825}#notice{font-size:13px;color:#5a7252}#text{margin-top:28px}#text h2,#text h3{margin-top:35px}a{color:inherit}pre{overflow:auto;background:#e8eee2;padding:16px}table{width:100%;border-collapse:collapse}td,th{padding:8px;border:1px solid #cbd8c2}#quiz button{display:block;padding:10px;margin:8px 0;background:#e4ecdc;border:1px solid #c7d6bd;border-radius:5px;color:inherit}footer{font-size:12px;margin-top:35px}@media(max-width:780px){main{grid-template-columns:1fr;gap:18px}nav{display:flex;overflow:auto}nav button{min-width:180px}h1{font-size:30px}}