code-lab/node_modules/vuetify/lib/components/VCard/_mixins.scss

@mixin card-line-height-densities ($map) {
  @each $density, $lineHeight in $map {
    @if $density == null {
      .v-card & {
        line-height: $lineHeight;
      }
    } @else {
      .v-card--density-#{$density} & {
        line-height: $lineHeight;
      }
    }
  }
}