* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "Segoe UI", system-ui, sans-serif;
  color: #1f2937;
  background: #f8fafc;
  line-height: 1.72;
}
a { color: #7c3aed; }

.a3-top {
  position: sticky;
  top: 0;
  z-index: 40;
  background: rgba(248, 250, 252, 0.96);
  border-bottom: 1px solid #ddd6fe;
  padding: 12px 18px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}
.a3-brand { font-size: 22px; font-weight: 800; color: #4c1d95; }
.a3-brand span { color: #7c3aed; }
.a3-btn {
  display: inline-block;
  padding: 10px 20px;
  border-radius: 10px;
  text-decoration: none;
  background: #7c3aed;
  color: #fff !important;
  font-weight: 700;
  font-size: 14px;
  border: none;
  cursor: pointer;
}

.a3-wrap { max-width: 940px; margin: 0 auto; padding: 0 18px 48px; }
.a3-hero { text-align: center; padding: 34px 0 20px; }
.a3-hero h1 { margin: 0 0 12px; font-size: clamp(27px, 4.2vw, 39px); color: #4c1d95; }
.a3-lead { margin: 0 auto 18px; max-width: 680px; color: #475569; font-size: 18px; }

.a3-toc {
  background: #fff;
  border: 1px solid #ddd6fe;
  border-radius: 14px;
  padding: 18px 22px;
  margin-bottom: 24px;
}
.a3-toc h2 { margin: 0 0 10px; font-size: 16px; color: #6b7280; }
.a3-toc ol { margin: 0; padding-left: 20px; }
.a3-toc a { text-decoration: none; font-weight: 600; }

.a3-sec {
  background: #fff;
  border: 1px solid #e9d5ff;
  border-radius: 16px;
  padding: 28px;
  margin-bottom: 20px;
  box-shadow: 0 4px 20px rgba(124, 58, 237, 0.06);
}
.a3-sec h2 { margin-top: 0; color: #4c1d95; font-size: 22px; }
.a3-sec p { color: #374151; }

.a3-cards {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
  margin-top: 16px;
}
.a3-cards div {
  background: #faf5ff;
  border-left: 4px solid #a78bfa;
  border-radius: 10px;
  padding: 14px;
}
.a3-cards h3 { margin: 0 0 6px; font-size: 16px; color: #581c87; }

.a3-box {
  text-align: center;
  padding: 22px;
  border-radius: 12px;
  background: linear-gradient(135deg, #f3e8ff, #faf5ff);
  margin: 20px 0;
}
.a3-box a { font-size: 22px; font-weight: 800; }
.a3-copy {
  margin-top: 10px;
  padding: 10px 18px;
  background: #fff;
  border: 2px solid #7c3aed;
  color: #7c3aed;
  border-radius: 8px;
  font-weight: 700;
  cursor: pointer;
}

.a3-faq details { border-top: 1px solid #e5e7eb; padding: 12px 0; }
.a3-faq summary { cursor: pointer; font-weight: 600; }
.a3-foot { text-align: center; padding: 24px; color: #6b7280; font-size: 14px; }

@media (max-width: 640px) { .a3-cards { grid-template-columns: 1fr; } }