How to tell my boss he's webdesign attempts are bad/hopeless?

I'm a web dev. My boss is an outdated physical media designer. We're working together on a relatively huge food delivery web system.

He just keep coming with these poor and ugly layout ideas. Clearly web-outsider stuff. See image below and tell me if I am wrong:

I just can't let it happen and "just work and get paid in the end of the month", because I have a share of the company's profits, and well, I want it to be good. I don't want to just lose my time. Also, I'm just a programmer, not a designer, as he always remembers me out loud.

So, guys, I'm desperate. Getting unmotivated. What to do?