kapitiseniornet on "Partial Black out of headings"

Have upgraded Firefox to v.20.0 but problem still persists. Since you have not got the problem when viewing the blog I must assume the problem lies with something applicable just to Firefox on my machine. Though at a loss to know what. This is what it look like:
<img class="alignleft wp-image-4586" alt="Capture" src="http://kapitiseniornet.files.wordpress.com/2013/04/capture.jpg?w=150" width="300" height="22" />