Missing Options for Customizing Theme and Opacity Level

[plawlost]

Description:

Currently, the Dark Coordinates extension provides a dark theme for displaying the mouse coordinates, but there is no way for users to customize this theme or adjust the opacity level. The README.md mentions that an options page exists where users can make these customizations, but this feature is not currently implemented.

I propose adding an options page to the extension where users can choose between a dark or light theme for the coordinates display, as well as adjust the opacity level with a slider. This would provide a more customizable experience for users and make the extension more versatile.

Thank you for your attention to this issue.