@yor-mozilla-com right now we only have one way to override styles defined in the component, which is using !important.
So the best way to avoid this issue is not setting a background image in `gaia_header/style.css`.
So please replace:
`[data-icon]:before {
  ...
  background: transparent no-repeat center / 3rem auto;`
with:
`background-repeat: no-repeat;
  background-position: center;
  background-size: 3rem auto;`