change icons based on github theme

[rohanprasadofficial]

Is your feature request related to a problem? Please describe. As we know Github released their dark mode recently and many icons are not visible now properly.

Describe the solution you'd like We need to add more icons like light foreground for dark bg and dark foreground for light bg and render based on the theme. We can detect the GitHub theme based on the tag on the page of the index.

html lang="en" data-color-mode="dark" This is a dark mode.

html lang="en" data-color-mode="light" This is the light mode.  

[rishavanand]

I guess we'll need JS to detect the color mode and GitHub MD does now allow that.