:root{
  --bg:#f7f8fa; --surface:#ffffff; --text:#1c2430; --muted:#5b6675; --line:#dfe4ea;
  --accent:#1f4e8c; --accent-soft:#e8eef7; --warn-bg:#fff6e5; --warn-line:#e7c77a;
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --bg:#10151c; --surface:#171e27; --text:#e6eaf0; --muted:#9aa6b5; --line:#2a3441;
    --accent:#7fb0ee; --accent-soft:#1b2a3f; --warn-bg:#2a2314; --warn-line:#6b5522;
  }
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--text);
  font-family:"Hiragino Sans","Yu Gothic UI","Meiryo",system-ui,sans-serif;line-height:1.85;font-size:16px}
a{color:var(--accent)}
.wrap{max-width:760px;margin:0 auto;padding:0 16px}
header.site{background:var(--surface);border-bottom:1px solid var(--line)}
header.site .wrap{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:8px 20px;padding-top:14px;padding-bottom:14px}
.brand{font-weight:700;letter-spacing:.02em;color:var(--text);text-decoration:none;font-size:18px}
nav a{margin-right:16px;text-decoration:none;font-size:14px;color:var(--muted)}
nav a:hover,nav a[aria-current]{color:var(--accent)}
.hero{background:#0d2a5c;line-height:0}
.hero img{display:block;width:100%;height:auto}
@media(min-width:641px){.hero img{height:clamp(240px,34vw,480px);object-fit:cover;object-position:center}}
main{padding:36px 0 56px}
h1{font-size:28px;line-height:1.4;margin:0 0 12px}
h2{font-size:20px;margin:40px 0 12px;padding-bottom:6px;border-bottom:2px solid var(--line)}
h3{font-size:17px;margin:24px 0 6px}
.lead{font-size:18px;color:var(--muted);margin:0 0 8px}
.card{background:var(--surface);border:1px solid var(--line);border-radius:10px;padding:18px 20px;margin:14px 0}
.card h3{margin-top:0}
.grid{display:grid;gap:14px}
@media(min-width:640px){.grid.two{grid-template-columns:1fr 1fr}}
.tag{display:inline-block;font-size:12px;padding:1px 9px;border-radius:99px;background:var(--accent-soft);color:var(--accent);margin-right:6px}
.note{background:var(--warn-bg);border:1px solid var(--warn-line);border-radius:10px;padding:14px 18px;margin:20px 0;font-size:15px}
table{border-collapse:collapse;width:100%;font-size:15px}
th,td{border:1px solid var(--line);padding:8px 10px;text-align:left;vertical-align:top}
th{background:var(--accent-soft)}
footer.site{border-top:1px solid var(--line);background:var(--surface);padding:24px 0;font-size:13px;color:var(--muted)}
footer.site a{margin-right:14px}
ul{padding-left:1.3em}
.meta{font-size:13px;color:var(--muted);margin:0 0 8px}
.meta a{color:var(--muted)}
.card h3 a{text-decoration:none}