Automatically switch between day and night themes

[chachako]

I hope that two themes can be set, which are displayed during the day and night respectively.

In the github night mode, displaying the white README element is really bad~~

[weensy]

I totally agree. Since we can't use CSS in README.md, we need to do something about it.

[rickstaa]

Putting this guide here as a reference. I will probably update the README in the future so that we can close this PR.

[rickstaa]

Related to:

• Support different themes on light and dark mode. #1645
• Toggle for the themes background color to match the GitHub dark/light mode background color #1182
• White and dark theme working at the same time #897
• Provide a functionality that inherits background of repo card according to git-hub dark/light mode #777
• A solution so that the stats theme changes with the GitHub theme. #739
• Add dynamic theme selection for cards #1036
• Add support for dark mode #689
• Switch theme depending upon prefers-color-scheme? #414
• [Feature] Dark mode #79
• [Feature] Support for dark mode #693
• Dynamic themes #1415
• Transparent Cards #690
• Dynamic theme based on viewer's github theme? #1880
• Auto Apply with browser dark mode #1684
• Translucent/transparent card themes #1920

People are now advised to use this trick.

[rickstaa]

Things that need to be done to close this issue:

• Merge one of the following transparent themes:
  • added transparent theme #1824, Add transparent theme #1785, Modify the transparent background to be compatible with adaptive dark… #1088, Transparent theme #1010.
• Document this theme in the README. Document auto theme change in README #2074
• Document auto theme change code in README. Document auto theme change in README #2074

[rickstaa]

I just included a default transparent theme which has a contrast ratio of more than 4.5 in both black and white. We will only include this transparent theme for now. If you want to make your own transparent theme, you can set the bg_color to ffffff00.

https://github-readme-stats.vercel.app/api?username=anuraghazra&title_color=006AFF&icon_color=0579C3&text_color=417E87&bg_color=ffffff00&show_icons=true

[![Anurag's GitHub stats](https://github-readme-stats.vercel.app/api?username=anuraghazra&theme=transparent&show_icons=true)](https://github.com/anuraghazra/github-readme-stats)

[rickstaa]

Closing this since we have included all the currently available methods for creating a dynamic theme in documentation #2229 (see https://github.com/anuraghazra/github-readme-stats#responsive-card-theme).