I have designed a page which is taller than a single screen and it works fine. However, when the same design is shorter than the screenheight the page sits the left by just a few pixels.

It means that if if a click through my site the page is not always strange,

Is their a method of ensuring a page is at least the height of the screen?

Some pages will be different heights as the content is echoes from a database. One page could 20 screens tall whilst another is currently half a screen height tall.

Any suggestions on how to fix this please?