CSS is driving me insane

I’m a CSS noob trying to put together my first wordpress theme from bits and pieces I’ve cobbled together off of the plain vanilla theme. Anyway, I’m trying to place an image at the top of the page using the “<img src” tag and the image shows up just fine BUT there’s an incredibly annoyin 3-5px margin that appears below the image THAT I CANNOT ELIMINATE. It is making me insane! ?? I have no clue what to do in my stylesheet to make it go away.

If anyone can check this out and point me towards the right setting on my stylesheet or tell me what to add to my stylesheet to get rid of this I will love you forever. Its like there’s a setting somewhere telling my system to add a margin to the bottom of any images I place.

https://www.passinreviewonline.com/wordpress is my blog.

I can paste my stylesheet below if people think it will help. Thanks!