Social Media: new LinkedIn button sits over Facebook button's text

This is related to CRM-10679.

The Facebook button for the Social Media panel has text to the right ("be the first of your friends ..."). The LinkedIn button introduced in CRM-10679 sits over this text (the Facebook material is set to 105px wide but contains an IFRAME whose content width is 300px).

The attached patch ...

• adds CSS to set the Social Media buttons to a default height and width
• adds a style to the Facebook DIV to make it 300px wide

Perhaps a more robust solution would be to add a CSS class to each Social Media button so the appearance could be controled from the CSS.