When you click on an image and it opens on the black background

Hi, When you click on an image in a post it opens not in a new window – but it almost looks like it.

It hovers over a black background – and you have to hit the back browser button to go back to your page.

Is there a way that if you click the picture or you click the black background it will go back to the page? It’s a little counter intuitive that it opens and you have to click the back button with no instructions… it puzzles first time users.

Thanks
LA