They can tell if you let it use whatever CSS it wants (Claude will nearly always make a purple or blue website with gross rainbow gradients). They can also tell if you let it write your marketing copy.

If you decide on your own brand colors and wording, there’s very little left about the code that can’t be done instantly by an LLM (at least on a marketing website).

I just read Claude's front-end design instructions, and it now explicitly bans purple gradients. Curious to see what new pattern it will latch on to.