message: Fix background color of phone field label on dark theme
  This adds extra styles to reset the field label background color on registration
  even if dark theme is used.
diff: @@ -52,11 +52,16 @@ limitations under the License.
  color: $authpage-primary-color;
  }
  -.mx_AuthBody .mx_Field input:focus + label,
  -.mx_AuthBody .mx_Field input:not(:placeholder-shown) + label,
  -.mx_AuthBody .mx_Field select + label /* Always show a select's label on top to not collide with the value */ {
  +.mx_AuthBody {
  + .mx_Field input:focus + label,
  + .mx_Field input:not(:placeholder-shown) + label,
  + .mx_Field textarea:focus + label,
  + .mx_Field textarea:not(:placeholder-shown) + label,
  + .mx_Field select + label /* Always show a select's label on top to not collide with the value */,
  + .mx_Field_labelAlwaysTopLeft label {
  background-color: $authpage-body-bg-color;
  }
  +}
  .mx_AuthBody input.error {
  color: $warning-color;
  