The white gap seams to be caused by this code:

element.style {
height: 150px;
}
So I just added that to the custom css and changed it to 0px.
But its still appearing as 150px even after I clear all caches.
Please note this appears only on the 1st visit of the site, an uncached version, so please make sure you are viewing it in an incognito window.
I think its coming form this header.masthead, but if I add the previous code:
header.masthead {
height: auto !important;
}
It gives me the same issue as before, I just need that gap removing from the homepage, not all pages.