width code - Since you have no way of knowing the screen resolution used by FReepers, using width=600, as an example, may work fine for me but may overscan on a FReeper’s monitor with a resolution less than mine.
I’ve found a solution to this by using width=X%. By using a percent instead of pixels, you’re guaranteed the image will fit, no matter the screen resolution. I have found using percentages between 50 and 80 work well depending on the image.
% - thanks. My html skills just doubled. ;)