Font size responsive

Hello,

I have another question to your nice Framework.

I saw that on the site: http://www.t3-framework.org/ the Font sizes are responsive. Means when i resize my screen into a smaler one the fontsize of h1 will become smaler after the breakpoint ist reached.

But it is not working on my site http://www.t3-framework.org/media/com_easydiscuss/images/markitup/emoticon-unhappy.png" /> and i don´t know why. I didn't set my h1 and others in a custom.css or so... I only used the calculated ones form variables.less with a base of 14px
The problem is that on my Joomla site http://sporttauchclub-leonberg.de/bilder2 the headings overlap when the screen gets smaler..

Thanks for your help!!!
Philopin