Why the page is scrolled to the bottom? what's wrong?

On #page-content is set to min-height in the file custom.js on line 40

$('#page-content').css({ 'min-height': page_height })

Remove this code, and so you have the slider height is set by the slider.

framework.css

line 74, remove the reference body
line 107: add a couple of lines:

height: 100%;
overflow: hidden;