Use light on dark icons for linux and rpi + sizing and padding - #728

Changed pages include:

• index.html - view
• 404.html - view
• 404/index.html - view
• 429/index.html - view
• books/index.html - view
• donate/index.html - view
• download/index.html - view
• environment/index.html - view
• examples/index.html - view
• overview/index.html - view

There are more changes not included in the list