improve: visual accessibility

[varjmes]

Off the top of my head are the visuals of our links. They are not well contrasted, nor do they have hover states. This is just a reminder issue to look at this stuff once hoodie-css is on its way to being finished :)

[lewiscowper]

From: this comment and this comment too we now have a list

• - Improve the contrast ratio between elements and text. Particularly were we use a lot of greys
• - Make sure we have good :active, :hover and :focus states on all our focusable/activable/hoverable elements (like links and buttons)
• - Make sure all images have appropriate alt tags - http://a11yproject.com/posts/alt-text/
• - Ensure all forms are appropriately structured, with labelling for and connect to each input
• - Use semantic HTML5 elements wherever possible

Completing this list shouldn't affect how the site looks in any major way, aside from perhaps the form input labelling, which may change structure slightly, though I'm more than up for removing it from this list and keeping it as an open issue for later.