Small cosmetic tweaks

[mvanrongen]

The footer with the license info is a bit too prominent, I think. Can be reduced in size.

[tavareshugo]

A few minor tweaks:

• [x] Move search to sidebar
• [ ] Check if logo can be made bigger
• [ ] Check if font for section titles can be tweaked
• [x] Make footer smaller
• [x] Check about colour scheme for header (e.g. lighter background with coloured text)