Add ::before element on displayed ad units

[benlk]

Changes

• Adds a ::before element on ad units that have a .display-block class (only added when creative has been fetched and is being displayed)

It even works on headers:

Here's how big it is:

[benlk]

Do we want to keep the set color, or let it inherit the theme's colorscheme for text in this widget? Right now it inherits the fonts.

[aschweigert]

keep the set color

[benlk]

No margin-bottom still has a slight spacing, which is nice.