:root {
  --bg: #ffffff;
  --surface: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --border: #e5e7eb;
  --radius: 14px;
  color-scheme: light;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Hiragino Sans", "Noto Sans JP", "Yu Gothic UI", Meiryo, system-ui, sans-serif;
  line-height: 1.6;
  -webkit-text-size-adjust: 100%;
}

.site-header {
  text-align: center;
  padding: 40px 16px 12px;
}
.site-header h1 { margin: 0; font-size: 1.8rem; }
.tagline { margin: 8px 0 0; color: var(--muted); font-size: 0.95rem; }

.layout {
  display: grid;
  gap: 16px;
  max-width: 720px;
  margin: 0 auto;
  padding: 24px 16px 48px;
  grid-template-columns: minmax(0, 1fr);
}

@media (min-width: 640px) {
  .layout { grid-template-columns: repeat(2, 1fr); }
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
}

.tool-card {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  text-decoration: none;
  color: inherit;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
.tool-card:hover,
.tool-card:focus-visible {
  border-color: #c7d2fe;
  box-shadow: 0 4px 16px rgba(79, 70, 229, 0.12);
}

.tool-icon {
  flex: none;
  width: 40px;
  height: 40px;
}
.tool-icon svg { width: 100%; height: 100%; }

.tool-body {
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.tool-title { font-weight: 600; font-size: 1.05rem; }
.tool-desc { color: var(--muted); font-size: 0.88rem; }

.site-footer {
  text-align: center;
  padding: 24px 16px 40px;
  color: var(--muted);
  font-size: 0.8rem;
}