:root{
  --bg:#ffffff; --bg-soft:#f3f7fc; --text:#0a1a33; --muted:#4f5f78; --line:#e2e9f3;
  --accent:#1260b0; --accent-2:#18bbe6; --accent-ink:#ffffff; --accent-soft:#e8f2fc;
  --radius:14px; --max:880px;
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --bg:#07111f; --bg-soft:#0c1a2e; --text:#e9f1fb; --muted:#97a9c3; --line:#1a2b45;
    --accent:#3d9be9; --accent-2:#18bbe6; --accent-ink:#04101f; --accent-soft:#0f2742;
  }
  :root:not([data-theme="light"]) .mark{background:#fff;padding:2px}
}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--text);
  font-family:Inter,system-ui,-apple-system,"Segoe UI",Roboto,"Noto Sans","Hiragino Sans","Hiragino Kaku Gothic ProN","Yu Gothic","Noto Sans JP",sans-serif;line-height:1.7;-webkit-font-smoothing:antialiased}
a{color:var(--accent)}
.wrap{max-width:var(--max);margin:0 auto;padding:0 16px}
header{border-bottom:1px solid var(--line);position:sticky;top:0;z-index:5;background:color-mix(in srgb,var(--bg) 90%,transparent);backdrop-filter:blur(10px)}
.nav{display:flex;align-items:center;justify-content:space-between;height:60px;gap:12px;max-width:1120px;margin:0 auto;padding:0 16px}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--text);font-weight:700;letter-spacing:.04em}
.mark{width:32px;height:32px;border-radius:50%;display:block}
.btn{display:inline-flex;align-items:center;justify-content:center;padding:11px 18px;border-radius:10px;font-weight:600;text-decoration:none;border:1px solid transparent}
.btn-primary{background:var(--accent);color:var(--accent-ink)}
.btn-ghost{border-color:var(--line);color:var(--text)}
.btn:focus-visible,a:focus-visible{outline:2px solid var(--accent-2);outline-offset:2px}
.crumbs{font-size:.82rem;color:var(--muted);padding-top:28px}
.crumbs a{color:var(--muted)}
.hero{padding:28px 0 40px}
.eyebrow{display:inline-block;font-size:.8rem;font-weight:600;color:var(--accent);background:var(--accent-soft);padding:5px 12px;border-radius:999px;margin-bottom:14px}
h1{font-size:clamp(1.9rem,4.6vw,2.8rem);line-height:1.2;letter-spacing:-.02em;margin:0 0 16px}
h1::after{content:"";display:block;width:56px;height:4px;margin-top:18px;border-radius:2px;background:linear-gradient(90deg,var(--accent),var(--accent-2))}
h2{font-size:clamp(1.3rem,2.6vw,1.7rem);line-height:1.3;margin:48px 0 12px;letter-spacing:-.01em}
h3{font-size:1.05rem;margin:0 0 6px}
p,li{color:var(--muted)}
.lead{font-size:1.12rem}
.cta{display:flex;flex-wrap:wrap;gap:12px;margin-top:24px}
.grid{display:grid;grid-template-columns:repeat(2,1fr);gap:14px;margin-top:16px}
@media (max-width:640px){.grid{grid-template-columns:1fr}}
.card{border:1px solid var(--line);border-radius:var(--radius);padding:20px;background:var(--bg)}
.card p{margin:0}
ol.steps{padding-left:20px}
ol.steps li{margin-bottom:8px}
ol.steps b,ul b{color:var(--text)}
details{border:1px solid var(--line);border-radius:12px;padding:14px 16px;margin-top:10px;background:var(--bg)}
summary{cursor:pointer;font-weight:600;color:var(--text)}
details p{margin:10px 0 0}
.band{background:var(--bg-soft);border-top:1px solid var(--line);margin-top:56px;padding:40px 0}
.related{display:flex;flex-wrap:wrap;gap:10px;margin-top:12px}
.related a{padding:8px 14px;border:1px solid var(--line);border-radius:999px;text-decoration:none;color:var(--text);font-size:.9rem;background:var(--bg)}
.related a:hover{border-color:var(--accent)}
.src{font-size:.82rem}
footer{border-top:1px solid var(--line);padding:28px 0;font-size:.84rem;color:var(--muted)}
footer a{color:var(--muted)}
:lang(ja) h1,:lang(ja) h2,:lang(ja) h3{word-break:auto-phrase;line-break:strict}