Image width

SO I have a header that I made and I want it to stretch over the whole top of a browser; how do I make it so it only goes 100% on all browsers, and not more or less on others?

Thats a toughie.

Browser windows change size depending on resolution. I suggest a maximum image width of 760 pixels to fit it within a 800x600 resolution browser window. The missing 40 pixels are usually eaten by the browser window itself, such as the small left side border and the scroll bar area on the right.

If you want a banner/header that will always be at the edges of any browser window at any resolution, some HTML will have to be involved. Make a header graphic at whatever pixel width you want (at or under 760 pixels of course). Use a flat color for the header's background. Put the graphic into a html table. Keep the table's width at 100%. You will want to make the table have a fixed pixel height of whatever height your header graphic is. Don't have it hug the edges of the graphic with a fixed pixel width value. Now, add the color of your header's background as the color of the table's background. They should blend together at this point and you will have a top bar that will always be at the edges of any browser window.

You could get fancy and try to make a more detailed background tile by getting a background tile to match up with header. I suggest using only straight horizontal lines if you try that.