Me again

Rather than start a new topic I'll just add this question to this one, since it's related...
Basically I changed a bit of code to add an image to the hyperlink that links to the list in a master/detail relationship...
<A href="_event_themes_list.php?{$row.1_event_themes_masterkeys}"><IMG alt="Add Theme" src="images/add_theme.gif"></A>
Changes the text hyperlink to an image one

However there is an odd side effect... The image is now surrounded by a purple border
I can't find anything in the HTML code or CSS stylesheet that would account for it... Anybody got any ideas what it is and how to get rid of it?
Thanks again
EDIT: All sorted... Changed the code to this...
<A href="_event_guests_list.php?{$row.1_event_guests_masterkeys}"><IMG alt="Add Guest" src="images/add_guest.gif" border=0></A>
I'm not sure where it was getting the instruction to have a border, but this gets rid of it