Big gap between header and post

Hi

A big gap has appeared on my blog between the header and the post which hasn’t been there previously. I have seen on some other requests for support that it’s probably to do with the css, and i’ve found the style sheet but not sure where to go next. Please can someone help?

And I would love to be able to increase slightly the size between the paragraphs……..

my website is http://www.inspiringinkin.com

Thanks ou so much in advance