:root{--ink:#1f2937;--muted:#6b7280;--navy:#1f2a44;--line:#e5e7eb;--bg:#f7f8fa}
*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font-family:-apple-system,BlinkMacSystemFont,"Hiragino Sans","Yu Gothic",Meiryo,sans-serif;line-height:1.85;font-size:15px}
header{background:var(--navy);color:#fff}header div{max-width:760px;margin:auto;padding:18px 20px}header a{color:#fff;text-decoration:none;font-weight:700}
main{max-width:760px;margin:24px auto;padding:28px 20px;background:#fff;border:1px solid var(--line);border-radius:8px}
h1{font-size:24px;line-height:1.45;margin:0 0 6px;color:var(--navy)}h2{font-size:18px;margin:30px 0 8px;color:var(--navy)}
p,li{margin:0 0 10px}ul{padding-left:22px}.muted{color:var(--muted);font-size:13px}code{font-size:13px;background:#f1f3f6;padding:1px 5px;border-radius:3px}
footer{max-width:760px;margin:0 auto 32px;padding:0 20px;font-size:12px;color:var(--muted)}footer a{color:var(--muted)}
@media(max-width:480px){main{margin:0;border:0;border-radius:0}}