The Toggle Document Colors add-on lets you easily toggle the page colors between the page-defined colors and your own user-defined color preferences. The colors may be toggled by means of a keyboard shortcut or a button on the toolbar.
The toolbar button is automatically added to the browser's navigation bar when the add-on is installed. If you don't want the button to display, or if you want to move it to a different position, right-click the navigation bar and select "Customize...". Then you will be able to drag the button with your mouse to a new position or off the navigation bar.
The default keyboard shortcut for Firefox is (Control-Shift-C).
The default keyboard shortcut for SeaMonkey is (Control-K).
For SeaMonkey, the shortcut is only intended for use in browser windows, not in mail windows.
The shortcut key can be modified on the "about:config" page, by updating either of these values:
Before updating the values, make sure that the new shortcut values you plan to configure are not already used by the browser or by any other installed add-on.
To configure your own browser page colors, select "Tools - Options..." from the Firefox menu, then select the "Content" tab, and then select the "Colors..." button. This opens a window where you can select the colors to use for the page background, text, and links. This window has either a checkbox, "Allow pages to choose their own colors, instead of my selections above", or a dropdown, "Override the colors specified by the page with my selections above". Using the Toggle Document Colors keyboard shortcut or toolbar button is equivalent to opening the aforementioned window and toggling the checkbox or dropdown selection. But using the keyboard shortcut or toolbar button is much simpler and quicker.
This add-on has additional functionality to avoid your own colors from clashing with the page-defined colors in situations where the page overrides the background color but not the text color, or where it overrides the text color but not the background color.
When you toggle the add-on to use the page-defined colors, your own color settings are saved, and the color settings are set back to default values (generally, black text and white background). When you toggle back to using your own colors, they are set back to your saved values.
To view your color preferences on the Firefox Options window while this add-on is installed, toggle to user-defined color mode before opening the Options window.
Otherwise the Options window will only display the default values (due to the above-mentioned functionality). Even though the default values are displayed, your personal colors settings are still saved.