:root {
  --bg: #f5f4f0;
  --surface: #ffffff;
  --surface-alt: #fbfaf7;
  --primary: #5b6c8c;
  --primary-hover: #4a5b7b;
  --primary-active: #3e4d68;
  --text: #2a2e35;
  --text-muted: #6b7280;
  --text-faint: #9aa0a8;
  --border: #e5e3dc;
  --tag-bg: #eef1f6;
  --tag-text: #5b6c8c;
  --shadow-sm: 0 1px 2px rgba(20, 24, 32, 0.04), 0 1px 1px rgba(20, 24, 32, 0.03);
  --shadow-md: 0 2px 6px rgba(20, 24, 32, 0.05), 0 1px 2px rgba(20, 24, 32, 0.04);
  --radius: 10px;
  --radius-lg: 14px;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  font-family:
    system-ui,
    -apple-system,
    'Segoe UI',
    'Hiragino Sans',
    'Yu Gothic UI',
    'Meiryo',
    sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  font-feature-settings: 'palt';
}

main {
  max-width: 1080px;
  margin: 0 auto;
  padding: 40px 24px 80px;
}

.site-header {
  text-align: center;
  margin-bottom: 40px;
}

.site-header h1 {
  font-size: 1.4rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  margin: 0 0 4px;
  color: var(--text);
}

.site-header .tagline {
  margin: 0;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.section {
  margin-bottom: 40px;
}

.section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: 12px;
  gap: 12px;
}

.section-head h2 {
  margin: 0;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.12em;
}

.style-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px 32px;
  box-shadow: var(--shadow-md);
}

.style-name {
  margin: 0 0 8px;
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: 0.01em;
  line-height: 1.3;
}

.style-description {
  margin: 0;
  color: var(--text-muted);
  font-size: 1rem;
  line-height: 1.65;
}

.topics-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-auto-rows: 1fr;
  gap: 14px;
}

.topic-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 16px;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 8px;
  transition:
    transform 0.15s ease,
    box-shadow 0.15s ease,
    border-color 0.15s ease;
}

.topic-card:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
  border-color: #d8d6cd;
}

.category-tag {
  align-self: flex-start;
  font-size: 0.7rem;
  color: var(--cat-text, var(--tag-text));
  background: var(--cat-bg, var(--tag-bg));
  padding: 2px 9px;
  border-radius: 999px;
  letter-spacing: 0.05em;
  font-weight: 500;
}

.topic-card[data-category='tools'] {
  --cat-bg: #e7ebef;
  --cat-text: #4a5563;
}
.topic-card[data-category='food'] {
  --cat-bg: #f5e9d3;
  --cat-text: #8a5e1f;
}
.topic-card[data-category='hobby'] {
  --cat-bg: #ece2f3;
  --cat-text: #6b4a96;
}
.topic-card[data-category='childhood'] {
  --cat-bg: #f5edcc;
  --cat-text: #8a6c1a;
}
.topic-card[data-category='travel'] {
  --cat-bg: #d9e9e9;
  --cat-text: #2c7a78;
}
.topic-card[data-category='bgm'] {
  --cat-bg: #f3dee7;
  --cat-text: #a04a72;
}
.topic-card[data-category='season'] {
  --cat-bg: #dce8d4;
  --cat-text: #4f7841;
}
.topic-card[data-category='lifestyle'] {
  --cat-bg: #efe1cd;
  --cat-text: #84613a;
}

.topic-text {
  margin: 0;
  font-size: 0.94rem;
  color: var(--text);
}

.btn {
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border);
  padding: 5px 12px;
  border-radius: 6px;
  font-size: 0.78rem;
  font-weight: 400;
  cursor: pointer;
  transition:
    color 0.15s ease,
    border-color 0.15s ease,
    background 0.15s ease;
  font-family: inherit;
  letter-spacing: 0.02em;
}

.btn:hover {
  color: var(--text);
  border-color: var(--text-faint);
  background: var(--surface);
}

.btn:active {
  background: var(--surface-alt);
}

.btn:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

.site-footer {
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
  margin-top: 56px;
  padding-top: 24px;
  border-top: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.footer-note {
  margin: 0;
}

.repo-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--text-faint);
  text-decoration: none;
  font-size: 0.78rem;
  transition: color 0.15s ease;
}

.repo-link:hover {
  color: var(--text-muted);
}

.repo-link:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
  border-radius: 4px;
}

.repo-icon {
  flex-shrink: 0;
}

.error-banner {
  background: #fde2e2;
  color: #8a1f1f;
  padding: 12px 16px;
  border-radius: var(--radius);
  margin-bottom: 24px;
  font-size: 0.9rem;
}

@keyframes flash-in {
  0% {
    opacity: 0.55;
    transform: translateY(2px);
  }
  100% {
    opacity: 1;
    transform: translateY(0);
  }
}

.flash {
  animation: flash-in 0.25s ease-out;
}

@media (max-width: 820px) {
  .topics-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 520px) {
  main {
    padding: 24px 16px 60px;
  }
  .topics-grid {
    grid-template-columns: 1fr;
  }
  .section-head {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }
  .style-card {
    padding: 18px 20px;
  }
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1c1d20;
    --surface: #25272b;
    --surface-alt: #2b2d32;
    --text: #e7e8eb;
    --text-muted: #a0a4ad;
    --text-faint: #707682;
    --border: #34373d;
    --tag-bg: #2e333d;
    --tag-text: #a7b3cf;
    --primary: #7d8eb1;
    --primary-hover: #8c9dc1;
    --primary-active: #6e7fa3;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.35);
  }

  .topic-card:hover {
    border-color: #444851;
  }

  .topic-card[data-category='tools'] {
    --cat-bg: #353b44;
    --cat-text: #b3bccc;
  }
  .topic-card[data-category='food'] {
    --cat-bg: #463a29;
    --cat-text: #d9b078;
  }
  .topic-card[data-category='hobby'] {
    --cat-bg: #3d2f48;
    --cat-text: #c2a4dd;
  }
  .topic-card[data-category='childhood'] {
    --cat-bg: #443a23;
    --cat-text: #d9c074;
  }
  .topic-card[data-category='travel'] {
    --cat-bg: #2c3f3f;
    --cat-text: #88c2c0;
  }
  .topic-card[data-category='bgm'] {
    --cat-bg: #422a35;
    --cat-text: #d990a8;
  }
  .topic-card[data-category='season'] {
    --cat-bg: #2e3b30;
    --cat-text: #94c089;
  }
  .topic-card[data-category='lifestyle'] {
    --cat-bg: #423829;
    --cat-text: #d4b285;
  }

  .error-banner {
    background: #4a2222;
    color: #f4c2c2;
  }
}