Extra space at top of header on inside content pages

I have a small hiccup with my Abstrakt Theme, and could use some help. (Please.) I know the answer might be simple, but so is my skill level with adjusting code on PHP and HTML pages.

On the front of my yet-to-be-made-public blog site, the header image is flush against the top of the page. However, if you click on a post or a page, or archive, there is suddenly a extra bit of black space between the header image, and the top of the page. I would like to get rid of this extra space.

I haven’t made any adjustments to the css file (I’m too chicken..) but I have adjusted elements on some of the theme php pages. I’m sure I must have just made a simple mistake, but I’m not sure where to look, or what I might have done.

Any quick pointers as to what to check, or where? FWIW – I’ve made sure there is no extra spaces in front of the first bit of code, i.e. <?php get_header(); ?>.

Thank you for looking, and in advance for any replies.