Hi,
I do not know "BBEdt". I use editors like "Notepad++" or "Scintilla" and you can use a little "search and replace" in order to replace ".modal{" by "div.modal{".
The problem is that, you are using a Bootstrap design with a Joomla 2.5 which does not include the bootstrap popups.
So we can just use the Joomla squeezebox which use the class "modal" on the links in order to find the links which open popups.
Because your template uses bootstrap without any Joomla 2.5 compatibility, it does not support the squeezbox CSS and display the links like it was a bootstrap modal box. But it's not.
The solution is to fix your template CSS by this replacement. You can also contact the person who made your template and ask him to make this fix for you.
But in HikaShop, we can't do anything special because, you have a Joomla 2.5 and there is not bootstrap popup in this version of Joomla. I am sure that the problem will be the same with other extension which display popups in the front-end.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.