I've always wondered how ycombinator handles design. Do they have designers on site , do teams hire designers to get it right or do they count on the teams to d

I've always wondered how ycombinator handles design. Do they have designers on site , do teams hire designers to get it right or do they count on the teams to do it on their own. I'm no good at design and I don't know anybody who's good at it. I just browse Themeforest and buy one if I need one.