:root {
  color-scheme: light;
  --bg: #ffffff;
  --bg-alt: #f6f9ff;
  --surface: rgba(255, 255, 255, 0.88);
  --surface-strong: #ffffff;
  --text: #0f172a;
  --muted: #475569;
  --line: rgba(15, 23, 42, 0.12);
  --accent: #1d4ed8;
  --accent-soft: rgba(29, 78, 216, 0.1);
  --shadow: 0 24px 60px rgba(15, 23, 42, 0.08);
  --radius-lg: 28px;
  --radius-md: 18px;
  --radius-sm: 12px;
  --content-width: 880px;
}

* {
  box-sizing: border-box;
}

html {
  background:
    radial-gradient(circle at top left, rgba(29, 78, 216, 0.1), transparent 30%),
    radial-gradient(circle at top right, rgba(15, 23, 42, 0.05), transparent 32%),
    linear-gradient(180deg, var(--bg) 0%, var(--bg-alt) 100%);
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--text);
  font-family: "Noto Sans", "Hiragino Sans", "Segoe UI", sans-serif;
  line-height: 1.65;
}

a {
  color: inherit;
  text-decoration: none;
}

a:hover {
  color: var(--accent);
}

.app-shell {
  width: min(var(--content-width), calc(100vw - 32px));
  margin: 0 auto;
  padding: 32px 0 48px;
}

.site-header {
  display: grid;
  gap: 22px;
  padding: 22px 24px 28px;
  background: var(--surface);
  backdrop-filter: blur(18px);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
}

.top-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--muted);
}

.brand-mark {
  width: 12px;
  height: 12px;
  border-radius: 999px;
  background: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
  box-shadow: 0 0 0 5px var(--accent-soft);
}

.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.nav a {
  padding: 9px 14px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.78);
  color: var(--muted);
  font-size: 0.92rem;
  font-weight: 600;
  transition: transform 140ms ease, border-color 140ms ease, color 140ms ease, background 140ms ease;
}

.nav a[aria-current="page"] {
  color: var(--text);
  border-color: rgba(29, 78, 216, 0.35);
  background: var(--accent-soft);
}

.nav a:hover {
  transform: translateY(-1px);
  color: var(--text);
  border-color: rgba(29, 78, 216, 0.25);
}

.title-block {
  display: grid;
  gap: 12px;
}

.eyebrow {
  font-size: 0.84rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 3.8vw, 3.2rem);
  line-height: 1.05;
  letter-spacing: -0.03em;
}

.intro {
  max-width: 70ch;
  margin: 0;
  font-size: 1.03rem;
  color: var(--muted);
}

.meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  color: var(--muted);
  font-size: 0.93rem;
}

.meta span {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.72);
  border: 1px solid var(--line);
}

.content {
  margin-top: 20px;
  display: grid;
  gap: 16px;
}

.section {
  padding: 22px 24px;
  background: var(--surface);
  backdrop-filter: blur(18px);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.05);
}

.section h2 {
  margin: 0 0 12px;
  font-size: 1.05rem;
  line-height: 1.3;
}

.section p {
  margin: 0 0 12px;
  color: var(--text);
}

.section p:last-child {
  margin-bottom: 0;
}

.section ul {
  margin: 0;
  padding-left: 1.2rem;
  color: var(--text);
}

.section li + li {
  margin-top: 8px;
}

.faq-list {
  display: grid;
  gap: 12px;
  margin-top: 6px;
}

.faq-item {
  overflow: hidden;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(29, 78, 216, 0.18);
  background: rgba(255, 255, 255, 0.76);
  transition: border-color 140ms ease, background 140ms ease, box-shadow 140ms ease;
}

.faq-item[open] {
  border-color: rgba(29, 78, 216, 0.28);
  background: rgba(255, 255, 255, 0.92);
  box-shadow: 0 12px 28px rgba(15, 23, 42, 0.06);
}

.faq-item summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 20px;
  color: var(--text);
  font-weight: 700;
  line-height: 1.4;
  cursor: pointer;
  list-style: none;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  content: "▸";
  flex: none;
  color: var(--accent);
  font-size: 1rem;
  transition: transform 140ms ease;
}

.faq-item[open] summary::after {
  transform: rotate(90deg);
}

.faq-item summary:hover {
  color: var(--accent);
}

.faq-item summary:focus-visible {
  outline: 2px solid rgba(29, 78, 216, 0.35);
  outline-offset: -2px;
}

.faq-answer {
  padding: 0 20px 18px;
}

.faq-answer p {
  margin: 0 0 12px;
  color: var(--text);
}

.faq-answer p:last-child {
  margin-bottom: 0;
}

.faq-answer ul {
  margin: 0;
  padding-left: 1.2rem;
  color: var(--text);
}

.faq-answer li + li {
  margin-top: 8px;
}

.contact {
  display: grid;
  gap: 10px;
  margin-top: 16px;
  padding: 18px 20px;
  border-radius: var(--radius-sm);
  background: rgba(29, 78, 216, 0.06);
  border: 1px solid rgba(29, 78, 216, 0.18);
}

.contact strong {
  display: block;
}

.footer {
  margin-top: 18px;
  color: var(--muted);
  font-size: 0.92rem;
}

.fallback {
  width: min(720px, calc(100vw - 32px));
  margin: 64px auto;
  padding: 24px;
  border-radius: 24px;
  background: #fff;
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}

@media (max-width: 640px) {
  .app-shell {
    width: min(100vw - 20px, var(--content-width));
    padding: 16px 0 24px;
  }

  .site-header,
  .section {
    padding: 18px 18px 20px;
  }

  .nav a {
    width: 100%;
    text-align: center;
  }
}