:root{--bg:#f7f8fb;--card:#fff;--text:#1b1d22;--muted:#5f6672;--line:#e5e8ef;--accent:#27364f}
*{box-sizing:border-box}body{margin:0;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Hiragino Sans","Yu Gothic UI","Yu Gothic","Noto Sans JP",sans-serif;color:var(--text);background:var(--bg);line-height:1.75}
header,main,footer{width:min(920px,calc(100% - 40px));margin:0 auto}header{padding:72px 0 28px}.brand{font-size:2.1rem;margin:0 0 6px}.tagline{color:var(--muted);margin:0}
nav{margin-top:24px;display:flex;gap:18px;flex-wrap:wrap}nav a,footer a{color:var(--accent);text-decoration:none;font-weight:600}
.card{background:var(--card);border:1px solid var(--line);border-radius:18px;padding:30px;margin:18px 0}h1,h2,h3{line-height:1.35}h2{margin-top:0}.muted{color:var(--muted)}
footer{padding:26px 0 56px;color:var(--muted);border-top:1px solid var(--line);margin-top:40px}