Is there a code you can put in your CSS to have a 1 px black border around all my images?

I have a lot of thumbnail photos on my web-site that enlarge when you click on them. But I'm wanting them to all have a black border around them.

Can I do this in an external CSS so that I don't have to add code to all my image pages?

img { border: 1px solid #000000; }

Add that to your external CSS file.

Thank you!