I did some digging around an found this. it allows one to change the background color of the webpages if they choose to.
im not sure if itll work if the HTML is programed in to be whatever color/s but thought id share just incase.

heres how to go about doing so in Firefox:

On the menu, go to Tools > Options
On the Options dialog box, click the Content tab (at the top)
Now, click the Colors button.
Uncheck the Use system colors check box and select the colors you want for the background and text (black and grey for example)
Uncheck the Allow pages to choose their own colors, instead of my selections above check box
Click OK to close the Colors dialog box.
Click OK to close the Options dialog box and apply the new settings


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an how to in Internet Explorer:

On the menu, go to Tools > Internet Options
On the Internet Options dialog box, click the Colors button (at the bottom left corner).
Uncheck the Use Windows colors check box, then change the text and background colors to the colors you want (I use black for the background and grey for the text), then click OK.
Next, click the Accessibility button (this time at the bottom right corner).
Check the Ignore colors specified on Web pages check box and click OK.
Click OK on the Internet Options dialog box to close it and apply the new settings.

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the website i got the tips off of has how to change the colors in other browsers too. heres the site: http://waldev.blogspot.com/2009/08/c...r-browser.html