Slight variations abound in scripts written by professionals.
That said, professional scripts will invariably resemble the formatting guide that follows. Your script does not have to mimic the following pages exactly, but it should closely resemble them. Top and bottom margins never seem to be maintained, and when printing, the page number will probably roll down the page. Be aware of the potential reduction when printing and so don't try to mimic the margins of the printed script but instead follow the margin, font, spacing guidelines found in the text itself. If you click on the text script button, you will have access to a text version of the script.