## cssVars · constant A reactive object containing CSS variable definitions. Any property you assign to `cssVars` becomes available as a CSS custom property throughout your application. Use `setSpacingCssVars` to optionally initialize `cssVars[1]` through `cssVars[12]` with an exponential spacing scale. When you reference a CSS variable in Aberdeen using the `$` prefix (e.g., `$primary`), it automatically resolves to `var(--primary)`. For numeric keys (which can't be used directly as CSS custom property names), Aberdeen prefixes them with `m` (e.g., `$3` becomes `var(--m3)`). When you add the first property to cssVars, Aberdeen automatically creates a reactive `