White space below all my slideshows on all pages

look at your quick css there is a rule:

#top .no_margin.av_one_fourth {
 padding:2px;
}

you have set instead of a closing an opening curly bracket!

Next : you have an opening media querry :

@media screen and (max-width:450px) {

but it does not close – go and have a look what rules must be surrounded by that media-query

if you got a full-slider solo on pages – there will be an automatic container after this. on most of your sites this will have the id: after_full_slider_1

so maybe this could solve your issue:

#after_full_slider_1 {
  display: none;
}

if there are other containers after the slider this automatic container will not be created.

For better contrast on your slider headings you can have a little outline with drop-shadow on them:

#top #main .avia-slideshow .avia-caption-title {
  color: #FFF;
  text-shadow:
	-1px -1px 0 #000,  
	 1px -1px 0 #000,
	-1px 1px 0 #000,
	 2px 2px 4px #000;
}