FireFox 4.0 does not display the vertical scroll bar unless it is needed. For the sake of discussion, let’s say the scroll bar is 20 pixels wide.

What if I have a set of Media Query CSS files that trigger on max-width and min-width at 1000 pixels.

When the overall browser window is 1030 pixels wide, my page displays with an extra column for my advertisements, this makes my content window smaller so the text is longer and it needs the scroll bar. My display window is 1030 – 20 or 1010 pixels so it uses the larger CSS file.

I change my overall window width to 1015 pixels. My overall display window is now 1015 – 20 or 995 pixels wide so it now uses the smaller CSS file. That file drops the advertisements which gives me more room for the content so the text is now shorter and no longer exceeds the page depth so the vertical scroll bar goes away. This makes my display 1015 – 0 or 1015 pixels wide so ???

Does Media Query recognize this and try to change back to the wider CSS file, which of course requires the vertical scroll bar that makes the window smaller so it wants to use the smaller CSS file, etc. in an infinite loop !

Does anyone know how media queries handles this?