Step 1: You-- not us-- will have to figure out how to represent your problem using the smallest possible amount of quoted html and css. Do not repeat do not simply dump the entire css into your post.
You need to do this because a moderator will be along shortly to delete the link to your site. This is in The Rules. It is doubly important for CSS because the question is about the site in its present form, not about what it will look like next year or next week.
And now, for the benefit of people coming along later, can you explain why the site has a seemingly superfluous vertical scroll bar although the overflow is horizontal? * It even happens in html preview using pasted-in page source. That's an extra scroll bar of its own, in addition to the browser-supplied one.
There is definitely something wrong with the page, because it takes far too long to load in relation to its size and content. But this isn't the place for a full-blown site review. I will add for the benefit of that same coming-along-later crowd that the front page includes about 65 style declarations (based on rough count of { characters minus a few in scripts) in addition to links to 11 (ELEVEN) external stylesheets. And, according to the text editor, 26 separate external javascript files.
And you're worried about whitespace? (Which, incidentally, I don't see. But I only tried two browser families, neither of them You Know What.)
* OK, n/m, that question at least is answered in the body of the document:
<!-- Responsive on demand -->
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
<style>
body, html {
width: 100%;
//height: 100%;
margin: 0px;
padding: 0px;
overflow-x: hidden;
}
</style>
Someone else will have to explain to me what "responsive" means in this context.