HTML - display an image as large as possible while preserving aspect ratio

Question

I\'d like to have an HTML page which displays a single PNG or JPEG image. I want the image to take up the whole screen but when I do this:

Answer 1

To piggyback on Franci Penov, yes you just want to set one of them. If you have a wide picture, you want to set width to 100% and leave height. If you have a long picture, you want to set height to 100% and leave width.