Fix tabs in IE7

IE7 does not have display: table. Before, the tabs had weird spacing and
were split across multiple lines. Now, they look like tabs, and, whilst
they're not exactly the same as in browsers from this decade, they're
acceptable.
Compose RGBA colours to RGB

IE7 can't do fractional alpha.
Give the Submit button space on IE7

By setting a height on the action bar, we can give it slightly better
spacing everywhere.
Button border looks wonky in IE7

It's better if we just remove it.
Eliminate html_safe

We can take advantage of SafeBuffer's HTML concatenation by building up
the string with inject instead of map and join.
Colour the score selectors

nth-child doesn't work in IE7. Instead, we give each radio choice an
offset class, and manually construct some HTML with classes for the
introductory text.