*, *::before, *::after { box-sizing: border-box; }
body, h1, h2, h3, p, ul { margin: 0; padding: 0; }
body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; background: #f8fafc; color: #1e293b; }

/* ── Header ── */
header { background: #1e3a5f; color: #fff; text-align: center; padding: 24px 20px 0; }
header h1 { font-size: 2rem; letter-spacing: 0.02em; }
header > p { margin-top: 6px; font-size: 0.95rem; color: #cbd5e1; }

header nav { margin-top: 16px; display: flex; justify-content: center; gap: 4px; }
header nav a {
  display: inline-block; padding: 8px 22px;
  color: #94a3b8; font-size: 14px; font-weight: 500; text-decoration: none;
  border-radius: 6px 6px 0 0;
  transition: background .15s, color .15s;
}
header nav a:hover  { background: rgba(255,255,255,.1); color: #fff; }
header nav a.active { background: #f8fafc; color: #1e3a5f; }

/* ── Layout ── */
.content { max-width: 820px; margin: 0 auto; padding: 24px 16px 60px; }
section  { margin-bottom: 32px; }

h2 { font-size: 1.25rem; font-weight: 700; color: #1e3a5f; margin-bottom: 12px; border-left: 4px solid #2563eb; padding-left: 10px; }
h3 { font-size: 1.05rem; font-weight: 600; margin-bottom: 8px; }

p { line-height: 1.7; color: #374151; font-size: 0.95rem; }
p + p { margin-top: 8px; }

.card { background: #fff; border: 1px solid #e2e8f0; border-radius: 10px; padding: 20px; }
.divider { border: none; border-top: 1px solid #e2e8f0; margin: 24px 0; }

/* ── Buttons ── */
.btn {
  display: inline-block; padding: 10px 24px; background: #2563eb;
  color: #fff; border-radius: 6px; text-decoration: none; font-size: 14px; font-weight: 600;
  border: none; cursor: pointer; transition: background .15s;
}
.btn:hover { background: #1d4ed8; }
.btn:disabled { background: #94a3b8; cursor: not-allowed; }

/* ── Notices ── */
.notice { padding: 10px 14px; border-radius: 6px; font-size: 13px; }
.notice-warn { background: #fff7ed; border: 1px solid #fed7aa; color: #9a3412; }
.notice-info { background: #eff6ff; border: 1px solid #bfdbfe; color: #1e40af; }

.recommend-link { color: #2563eb; font-weight: 600; text-decoration: none; }
.recommend-link:hover { text-decoration: underline; }

@media (max-width: 600px) {
  header h1 { font-size: 1.5rem; }
}