Wrap navigation paragraph in a nav tag.
Add an h1 for SEO, use the alt attribute inside the header for that as youre major tagline contains rotating text. Add alt, width and height attributes - they are required for validation.
No sense to have an h3 tag in the header here, rather add it to the h1 tag and add a hook for styling. Add class as a hook for styling.
Dont use inline styles, pad practice. Add class instead and style from the stylesheet.
Why break that line?
Wrap content in sections. Introduce aside tag for under construction disclaimer.
Using HTML5, introduce the footer tag.
LIME!
Introduce roles for good practive: http://www.w3.org/TR/wai-aria/roles
Replace h4 with h2, subheadings are now direct child of page heading.
Images need alt, height and width attribute to validate.
trying to add a favicon, surprisingly hard
SHAZAM! RESPONSIVO!
That is a lot of h2 headings. Rather use strong tag to convey importance instead.
Merge with David