HTML5 validation + less markup!

Hey Flo,

here are my little improvements of the day:

- <h2> should not be inside <p> tags
- There was a missing alt attribute and a "heigh" attribute
- I switched anchors to sections to make the scroll go a little less further
- I removed IE and JS detection classes which were not used (it's always 250 less bytes to download)

Cheers !