* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "Segoe UI", system-ui, sans-serif;
  color: #0f172a;
  background: #f0f9ff;
  line-height: 1.7;
}
a { color: #0369a1; }

.atom-wrap { max-width: 920px; margin: 0 auto; padding: 0 18px 48px; }
.atom-top {
  position: sticky;
  top: 0;
  z-index: 40;
  background: rgba(240, 249, 255, 0.95);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid #bae6fd;
  padding: 12px 18px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}
.atom-brand { font-size: 22px; font-weight: 800; color: #0c4a6e; }
.atom-brand span { color: #0284c7; }
.atom-btn {
  display: inline-block;
  padding: 11px 20px;
  background: #0284c7;
  color: #fff !important;
  text-decoration: none;
  border-radius: 10px;
  font-weight: 700;
  font-size: 14px;
  border: none;
  cursor: pointer;
}
.atom-hero {
  padding: 36px 0 24px;
  text-align: center;
}
.atom-hero h1 {
  font-size: clamp(26px, 4vw, 38px);
  margin: 0 0 12px;
  color: #0c4a6e;
}
.atom-lead { font-size: 18px; color: #475569; max-width: 640px; margin: 0 auto 20px; }
.atom-toc {
  background: #fff;
  border: 1px solid #e0f2fe;
  border-radius: 14px;
  padding: 18px 22px;
  margin-bottom: 24px;
}
.atom-toc h2 { margin: 0 0 10px; font-size: 16px; color: #64748b; }
.atom-toc ol { margin: 0; padding-left: 20px; color: #0369a1; }
.atom-toc a { text-decoration: none; font-weight: 600; }
.atom-section {
  background: #fff;
  border-radius: 16px;
  padding: 28px;
  margin-bottom: 20px;
  border: 1px solid #e0f2fe;
  box-shadow: 0 4px 20px rgba(2, 132, 199, 0.06);
}
.atom-section h2 { margin-top: 0; color: #0c4a6e; font-size: 22px; }
.atom-section p { color: #334155; }
.atom-cards {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
  margin-top: 16px;
}
.atom-cards div {
  padding: 16px;
  background: #f0f9ff;
  border-radius: 10px;
  border-left: 4px solid #38bdf8;
}
.atom-cards h3 { margin: 0 0 6px; font-size: 16px; }
.atom-inbox {
  text-align: center;
  padding: 20px;
  background: linear-gradient(135deg, #e0f2fe, #f0f9ff);
  border-radius: 12px;
  margin: 20px 0;
}
.atom-inbox a { font-size: 22px; font-weight: 800; }
.atom-copy {
  margin-top: 10px;
  padding: 10px 18px;
  background: #fff;
  border: 2px solid #0284c7;
  color: #0284c7;
  border-radius: 8px;
  font-weight: 700;
  cursor: pointer;
}
.atom-faq details { border-top: 1px solid #e2e8f0; padding: 12px 0; }
.atom-faq summary { font-weight: 600; cursor: pointer; }
.atom-foot { text-align: center; padding: 24px; color: #64748b; font-size: 14px; }
@media (max-width: 640px) { .atom-cards { grid-template-columns: 1fr; } }