*{box-sizing:border-box}body{margin:0;background:#f1f5fb;color:#17253f;font:16px/1.8 -apple-system,BlinkMacSystemFont,"Segoe UI","Microsoft YaHei",sans-serif}main{max-width:960px;margin:40px auto 0;padding:0 28px 32px}header{padding:36px;background:#142542;color:white;border-radius:22px}header img{width:42px;height:42px;object-fit:contain;vertical-align:middle;margin-right:12px}.brand{font-weight:750;letter-spacing:.04em}h1{font-size:36px;margin:18px 0 8px;line-height:1.25}header p{color:#becde2;margin:0}nav{display:flex;flex-wrap:wrap;gap:8px;margin:24px 0}nav a{background:white;border-radius:8px;padding:8px 14px;text-decoration:none;color:#305277;font-size:14px}section{background:white;border:1px solid #e1e8f2;border-radius:18px;margin:22px 0;padding:30px}h2{font-size:24px;line-height:1.5;margin:0 0 14px}.num{display:inline-flex;align-items:center;justify-content:center;width:34px;height:34px;color:white;background:#3278e9;border-radius:10px;margin-right:12px;font-size:18px}p{margin:12px 0}figure{margin:20px 0 8px}figure img{display:block;max-width:100%;height:auto;border-radius:12px;border:1px solid #e3e9f2;margin:auto}figcaption{font-size:13px;color:#697d99;margin-top:10px;text-align:center}.note{padding:12px 16px;border-left:3px solid #5087db;background:#eef5ff;border-radius:6px;color:#3a567c;font-size:14px}.smallpic{max-width:560px;margin-left:auto;margin-right:auto}.pair{display:grid;grid-template-columns:1fr 1fr;gap:24px}a{color:#236bd3}code{background:#edf2fa;padding:2px 5px;border-radius:4px}details{border-top:1px solid #e7ecf3;padding:14px 0}summary{font-weight:650;cursor:pointer}footer{color:#6a7b93;font-size:13px;padding:0 10px}ul{padding-left:24px}b{font-weight:650}@media(max-width:640px){main{padding:0 16px;margin:20px auto}header,section{padding:22px}h1{font-size:28px}h2{font-size:21px}.pair{grid-template-columns:1fr}}@media print{body{background:white}main{margin:0;max-width:none;padding:0}nav{display:none}header{print-color-adjust:exact}section{break-inside:avoid;border-radius:0}details{display:block}details p{display:block}}#help h2{margin-bottom:20px}#help details{border:0;padding:0}#help details+details{margin-top:22px}#help details p{margin:8px 0 0}footer{line-height:1.6}@media(max-width:640px){footer{padding-left:10px!important;padding-right:10px!important}}