Overriding HTML CSS element
===

I have recently added a Photoswipe gallery to my website which has the following CSS applied to it:

    html {overflow-y:scroll;overflow-x:auto;}

Now the problem is the full-screen gallery scrolls because of this overflow, but it should fit tight to the screen it's shown on, no scrolling. I don't want to remove it using jQuery as I was having problems with jQuery on this page. 

I tried:

    <style type="text/css">
    html {}
    </style>

With no luck. What else can I do to remove it?