Twenty Ten CSS not editing

I’ve recently inherited a site to update and this being my first wordpress gig I was slightly puzzled with regards to the CSS editor. The theme used is Twenty Ten.

I’m trying to just remove this little black bar on top of the header, yet nothing happens.

/* This is the custom header image */
#branding img {
	border-bottom: 1px solid #000000;
	border-top: none;
	display: block;
	float: left;
}

This is what I have right now. I’ve tried changing the color to match the BG color and still nothing. I then tried just making drastic edits to the css file and nothing shows. It still saves it in the css file, however. Regular changes via WP admin web interface work fine, just not this.

I’ve done a little forums digging and verified my host has write enabled (It’s iPage using up-to-date WordPress Script). I’ve tried locating the CSS file in iPage’s file library but all it has are a couple site backups and the WP install files.

Also note: I’ve read I should be using a “child-theme” and not alter this theme. I’m assuming that means some sort of hierarchical “sub-theme” running under this. But seriously, all I want is for this top border to go away. Nothing else different.

What am I missing?