Custom header icons size glitches on page refresh/reloading, fix?

[XMAN00]

Im using a custom cart icon and it fits perfectly well but whenever i refresh the page it always glitches for a second and it goes back to normal. It is annoying and I would like to get it removed. Ive tried everything. Can anyone help? (Right is how it looks when the page is reloading but it goes back to normal)