:root {
  --platform-font-family: "Segoe UI", "Yu Gothic UI", Meiryo, system-ui, sans-serif;
  --platform-radius-xs: 4px;
  --platform-radius-sm: 6px;
  --platform-radius-md: 8px;
  --platform-control-height: 34px;
  --platform-focus-ring: 0 0 0 3px rgba(31, 122, 112, 0.18);
  --platform-shadow-panel: 0 12px 28px rgba(15, 23, 42, 0.08);
  --platform-transition-fast: 120ms ease;
}