Page height in reference to length of wp-post ?

Hi,

Im having a problem resizing my pages to fit the length of the information on the screen. So far I have to set my page height to 1250 pixles (the size of my largest post on the website), but it looks terrible on page where I have a small amount of info. (lots of white space at the bottom, before the footer)

If I remove this page height, the footer jumps directly under my header. And the posts appear to overflow on top of the footer, to the bottom of the browser page.

Here is a link to my site https://www.flexhk.com/wordpress

Any help would be extremely appreciated! This has been bugging me for a few weeks now!!