:root { --ink:#1a1a1a; --muted:#525252; --line:#dcdcdc; --accent:#0b4a7f; }
* { box-sizing:border-box; border-radius:0 }
body { margin:0; font-family:"Hiragino Sans","Yu Gothic",Meiryo,sans-serif;
       color:var(--ink); line-height:1.8; }
header { border-bottom:3px solid var(--accent); padding:24px 32px; }
header h1 { margin:0; font-size:24px; font-weight:400 }
nav { padding:12px 32px; border-bottom:1px solid var(--line); }
nav a { margin-right:24px; color:var(--accent) }
main { max-width:820px; padding:32px }
footer { border-top:1px solid var(--line); padding:16px 32px; color:var(--muted); font-size:13px }
.mark { background:#f4f4f4; padding:8px 12px; display:inline-block; font-family:monospace }
img { max-width:200px; height:auto }