These are called Margins. They are default on all HTML pages.
You can get rid of those 2 by changing your body to to look like this…
<body leftmargin="0" topmargin="0">
If you would like to get rid of ALL the margins you can add to the tag with these…
That should fix your problem.
PS: Please run a search before you ask. This question is at least asked once a day when the problem could easily be solved by running a search. This is isn’t directed to you, it is directed to anyone who reads this thread. Running a search will usually help you find what you want, and if not, then post:)