Make tropo purple menu bg use primary color, not link color

Primary color is more suitable for accent/backgrounds. Link color may be
too bright (which we want for foreground)
Fix menu icon position on different font sizes

We use px because the position of the menu icon bg images should be
based on the size of the image, not the size of the text
Merge pull request #62 from afuna/tweak-foundation-from-feedback-round-4

Fourth round of changes for feedback