Deleted branding header. How do I get rid of the gap?

(I hope this is the right forum for this. My apologies otherwise. I tried WP-Advanced, but it said only moderators could post.)

In place of the branding header – the horizontal strip that runs across the top of the page, containing the blog title and description – I wanted my own complex header and navigation.

I found the page in the theme files that specified the branding header, commented it out, and substituted a PHP include to my main header file. This worked. In the browser source code, it shows my header just after the body tag, which is what I wanted.

Just one problem. The branding header is gone, but there’s a gap – a horizontal strip of blank space, the same height as the branding header – below my custom header and above the rest of the page. So either something is still calling for this space to be there – even without anything in it – or else the vertical position of what’s below it is being specified somewhere.

Unfortunately, although I’m fluent in HTML and ColdFusion, and can stumble around alright in PHP, I’m not experienced enough with WordPress or CSS to even know what to look for, much less where to look.

So how do I get rid of the gap?

Thank you.