Make pages more readable when viewing them on a small display

[bjansen]

This PR makes it easier to view SDK docs on a smartphone, mainly because of the new <meta> tag. Other CSS changes remove padding here and there to avoid having too much empty space on the screen.

Before:

After:

[bjansen]

Note: I'm not sure how app.css is supposed to be generated, so I ran sass on styles.scss to modify styles.css and copy/pasted my changes to app.css, but they are not correctly minified.