"Your Contribution" icons missing

When a contribution has been submitted and you receive the confirmation email, you can click on View Contribution Status. The resulting page marks Accepted entries with a green tick and Pending ones with a blue letter i.But recently in Firefox, the tick or i icons are not being displayed. Google Chrome is still displaying them. I've cleared the Firefox cache and it doesn't help.Is anyone else seeing this, or is it just me? If it's me, I'll look more closely at my setup.