Issue with megamenu and html custom module!

Hi there,
I hope someone can help me with this.
I am working with a megamenu on t3 framework and Joomla 3.1.5.
I am using a custom html module.
The megamenu works fine when I am on wide screen but when I go on a mobile screen the menu shows white lines under the links.
Please see the attachments.
Regards
Dany