Hi There,
There is a JavaScript error on your site that is related to RevSlider, the revslider javascript initialize on the header part. But your site loads the jQuery on the footer part.
Please do a testing for a plugin conflict. You can do this by deactivating all third party plugins, and seeing if the problem remains. If it’s fixed, you’ll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
Thanks.