Changing Font to Template Fonts

I have looked this the forum and at documention but I can't work this out. I want to change the top CSS Mega Menu to use the systems font which are google web fonts and also be able to change the size. Can you please help? Site is blairsigns.com.au/joomla34/ . Menu attached. Also I have made the menu sticky but doesn't seam to work.

Hi Blair,
Thanks for contacting us and choosing our product!
Sorry for late response because we just have weekend and our support staff for jux mega menu was got a sick.
So you can contact him direct via email address: This email address is being protected from spambots. You need JavaScript enabled to view it..
He'll help you to fix this problem asap!

Hi,
Sorry for the late reply, I miss work because of illness.
About you problem. Please go to module JUX CSS3 Mega Menu-> tab Advanced -> config Custom CSS
Add css
#jux_megamenucss3 .megamenu ul.level0 li.megacss3 span.menu-title{
font-size: 20px;
}
#jux_megamenucss3 .js-megamenu .megamenu i.jux-fa{
font-size: 18px;
margin-right: 10px;
}
If that is not the problem you please describe in more detail. I'll help you later. Thanks

Thanks, I can now easily change the font & icon sizes. How to I change the font to the Google web font used in my template. eg roboto slab

Hi
Please replace the font on your own

#jux_megamenucss3 .megamenu .js-megamenu{
font-family: Helvetica, Arial, sans-serif;
}
Thanks

Thank you so much, I worked it out. I can not use any web font I like.

Hi Blairsigns,
Sorry for the late reply,
Please try again font you're using. maybe it is not true. should not operate. Thanks