:root{
  --blue-900:#0b3d91;
  --blue-700:#1f5bd8;
  --yellow-500:#ffd400;
  --text:#111827;
  --muted:#6b7280;
  --bg:#ffffff;
  --card:#f8fafc;
  --border:#e5e7eb;
  --shadow:0 8px 18px rgba(17,24,39,.06);
  --radius:14px;
}

*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,"Hiragino Kaku Gothic ProN","Noto Sans JP","Yu Gothic",sans-serif;
  color:var(--text);
  background:var(--bg);
  line-height:1.85;
}

a{color:var(--blue-900);text-decoration:underline}
a:hover{color:var(--blue-700)}

.container{max-width:980px;margin:0 auto;padding:0 16px}
main.container{padding-top:18px;padding-bottom:56px}

.site-header{
  position:sticky;top:0;z-index:30;
  background:linear-gradient(0deg,rgba(11,61,145,.92),rgba(11,61,145,.92));
  backdrop-filter:saturate(1.2) blur(6px);
  border-bottom:1px solid rgba(255,255,255,.10);
}
.site-header .container{
  display:flex;align-items:center;justify-content:space-between;
  gap:14px; padding:14px 16px;
}
.logo a{
  color:#fff;text-decoration:none;
  font-weight:900; letter-spacing:.02em;
  font-size:18px;
}
.main-nav{display:flex;align-items:center;gap:12px;flex-wrap:wrap}
.main-nav a{color:rgba(255,255,255,.92);text-decoration:none;font-weight:700;font-size:14px}
.main-nav a:hover{color:#fff;text-decoration:underline}

.btn{
  display:inline-flex; align-items:center; justify-content:center;
  border-radius:999px;
  padding:10px 14px;
  font-weight:800;
  font-size:14px;
  text-decoration:none !important;
  border:1px solid transparent;
  transition:transform .05s ease, box-shadow .15s ease;
}
.btn:active{transform:translateY(1px)}
.btn-primary{background:#fff;color:var(--blue-900);border-color:#fff}
.btn-ghost{background:transparent;color:#fff;border-color:rgba(255,255,255,.35)}
.btn-accent{background:var(--yellow-500);color:#1b1b1b;border-color:var(--yellow-500)}
.btn-primary:hover,.btn-accent:hover{box-shadow:0 10px 22px rgba(0,0,0,.12)}
.btn-ghost:hover{background:rgba(255,255,255,.10)}

.box{
  background:#fff;
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:16px;
  box-shadow:var(--shadow);
  margin:14px 0;
}
.box.soft{
  background:var(--card);
  border-color:var(--border);
}
.muted{color:var(--muted);font-size:14px}

h1{font-size:24px;line-height:1.35;margin:0 0 10px}
h2{font-size:18px;line-height:1.4;margin:22px 0 10px}
h3{font-size:16px;margin:18px 0 8px}

.content-article p{margin:10px 0}
.content-article ul{margin:10px 0 10px 20px}
.content-article li{margin:6px 0}
.content-article hr{border:none;border-top:1px solid var(--border);margin:18px 0}

.content-nav{
  display:flex;flex-direction:column;gap:10px;
}
.content-nav-title{
  font-weight:900;
  letter-spacing:.01em;
  color:var(--blue-900);
}
.content-nav-links{display:flex;flex-wrap:wrap;gap:10px}
.content-nav-links a{
  display:inline-flex;align-items:center;
  padding:8px 10px;border-radius:999px;
  background:#fff;border:1px solid var(--border);
  text-decoration:none;color:var(--blue-900);font-weight:800;font-size:13px;
}
.content-nav-links a:hover{border-color:var(--blue-700);box-shadow:0 8px 16px rgba(17,24,39,.06)}

.grid{
  display:grid;
  grid-template-columns:repeat(2,minmax(0,1fr));
  gap:10px;
}
.card-link{
  display:block;
  padding:12px 12px;
  background:var(--card);
  border:1px solid var(--border);
  border-radius:12px;
  text-decoration:none;
  font-weight:900;
  color:var(--blue-900);
}
.card-link:hover{border-color:var(--blue-700);box-shadow:0 10px 20px rgba(17,24,39,.08)}
@media (max-width:720px){
  .grid{grid-template-columns:1fr}
  .main-nav a{font-size:13px}
  h1{font-size:22px}
}

.site-footer{
  padding:24px 0;
  background:linear-gradient(180deg,#ffffff, #f7f9ff);
  border-top:1px solid var(--border);
}
.site-footer .btn-ghost{color:var(--blue-900);border-color:var(--border)}
.site-footer .btn-ghost:hover{background:#fff}