"I don't do X type of work" is pretty unrealistic and comes across as more stubborn than anything else. This is especially true in a small/scrappy company up to medium size companies where you're expected to wear multiple hats.
Maybe at Google you can get away with being the "person that does X-only" but that doesn't work in most companies.
Your job is to do _the thing_ if that thing includes front end work, then you do the front end work.
Maybe at Google you can get away with being the "person that does X-only" but that doesn't work in most companies.
Your job is to do _the thing_ if that thing includes front end work, then you do the front end work.