WordPress MU

Hello,

I am trying to update the login page for my website.

Link to login page:
http://eastcoasttechwriter.ca/wordpress/wp-login.php

There is a grey bar at the top and I can't seem to get rid
of it.

I have looked through the css files accompanying the page,
but can not seem to find this.

Does someone have experience with this?

Yes.

You're not editing core files of WP are you? That's a bad practice. They will get overwritten when you upgrade.

Get this:
http://wpmututorials.com/how-to/custom-branded-login-screen-for-wpmu/

And use FireFox with the Firebug add-on. It will show you the css for each and every element on the page.