Make ads more obvious that they are ads

[davidfischer]

• A few visual tweaks
  • Adds a box with a background color around the ad so as to separate it from other content.
  • Links are always underlined.
  • Text in footer ads is a bit smaller
  • Slightly increases the padding around the ad container
  • The "sponsored" and "ads served ethically" text is blended a bit with the background so it emphasizes the actual ad. It is also always centered even on footer ads (previously it was right aligned).
• Adds a dark theme for ads that looks good on the RTD theme but could be used elsewhere if needed.

Note: this doesn't change any of the CSS classes for of our ads. Ad blockers will continue to work as normal. This means we shouldn't need to contact our partners at Eyeo/AdblockPlus with respect to "acceptable ads".

Screenshots

Sidebar on RTD

Footer on RTD

Sidebar on Alabaster

Footer on Alabaster

[ericholscher]

Looks great. 💯