Looks really good! Definitely would use something like this for some quick pages alright.

Two minor pieces of feedback — when I click "Switch theme", it seems to take you to non-styled rather than the light theme, not sure if that's what was intended or not? Could be good to have buttons for both.

Also, you seem to be getting an SSL mixed content warning, purely because of the Kitten pic. Know that it's not a big deal for a demo page, but if you wanted to get rid of it, you could use something like LoremPixel.com — they support switching URLs to HTTPS and have a 'cat' category!