Child theme problem

Hi there,
After a couple of hiccups (I’m not sure what I did wrong) my whole website went lopsided. Because I didn’t know where I’d gone wrong I decided to delete the whole site.

I installed WordPress again, again using Twenty Ten. But when I made a child theme and imported the twentyten style.css my website suddenly turned to this https://knottop.com/

Any ideas why?
Much appreciated!