Review styles of simple cards

[basicavisual]

This issue for for simple cards (pic, description and title) for metadata rich cards see issue #16

In the mockup cards are simpler:

In decidim cards have more info:

You must do the following:

• remove borders and background color
• reduce space between picture and title
• remove description and / or buttons
• make title and picture clickable / linkable

[ghost]

Already addressed.