Add this at the top of your page to show errors on a PHP page:

ini_set('display_errors', 1);
ini_set('log_errors', 1);
error_reporting(E_ALL);

There's two options for changing a page's margins.
Michael Michael (175)
0

When you change a page's margins in Google Docs, you're changing the amount of space you want between the edge of the page and the text.