.foo {
  line-height: calc(1.5 + 0.5 * ((100vw - undefined) / NaN));
  --line-height: calc(1.5 + 0.5 * ((100vw - undefined) / NaN));
}
@media screen and (min-width: 1280px) {
  .foo {
    line-height: 2;
    --line-height: 2;
  }
}
@media screen and (max-width: 420px) {
  .foo {
    line-height: 1.5;
    --line-height: 1.5;
  }
}