docs: document auto theme change #2074 (#2229)

* Document auto theme change in README #2074

* Document auto theme change in README

Document auto theme change in README #2074 (update-1)

* Document auto theme change updates

#2074

* docs: improve dynamic theme documentation

Co-authored-by: rickstaa <rick.staa@outlook.com>

readme.md

@@ -85,6 +85,7 @@ Visit <https://indiafightscorona.giveindia.org> and make a small donation to hel
 -   [Top Languages Card](#top-languages-card)
 -   [Wakatime Week Stats](#wakatime-week-stats)
 -   [Themes](#themes)
+    -   [Responsive Card Theme](#responsive-card-theme)
 -   [Customization](#customization)
     -   [Common Options](#common-options)
     -   [Stats Card Exclusive Options](#stats-card-exclusive-options)
@@ -156,6 +157,95 @@ GitHub readme stats comes with several built-in themes (e.g. `dark`, `radical`,
 
 You can look at a preview for [all available themes](./themes/README.md) or checkout the [theme config file](./themes/index.js) & **you can also contribute new themes** if you like :D
 
+#### Responsive Card Theme
+
+[![Anurag's GitHub stats-Dark](https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true&theme=dark#gh-dark-mode-only)](https://github.com/anuraghazra/github-readme-stats#gh-dark-mode-only)
+[![Anurag's GitHub stats-Light](https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true&theme=default#gh-light-mode-only)](https://github.com/anuraghazra/github-readme-stats#gh-light-mode-only)
+
+Since GitHub will re-upload the cards and serve them from their [CDN](https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/about-anonymized-urls), we can not infer the browser/GitHub theme on the server side. There are, however, four methods you can use to create dynamics themes on the client side:
+
+##### Use the transparent theme
+
+We have included a `transparent` theme that has a transparent background. This theme is optimized to look good on GitHub's dark and light default themes. You can enable this theme using the `&theme=transparent` parameter like so:
+
+```md
+![Anurag's GitHub stats](https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true&theme=transparent)
+```
+
+<details>
+<summary>:eyes: Show example</summary>
+
+![Anurag's GitHub stats](https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true&theme=transparent)
+
+</details>
+
+##### Add transparent alpha channel to a themes bg_color
+
+You can use the `bg_color` parameter to make any of [the available themes](./themes/README.md) transparent. This is done by setting the `bg_color` to a colour with a transparent alpha channel (i.e. `bg_color=00000000`):
+
+```md
+![Anurag's GitHub stats](https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true&bg_color=00000000)
+```
+
+<details>
+<summary>:eyes: Show example</summary>
+
+![Anurag's GitHub stats](https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true&bg_color=00000000)
+
+</details>
+
+##### Use GitHub's theme context tag
+
+You can use [GitHub's theme context](https://github.blog/changelog/2021-11-24-specify-theme-context-for-images-in-markdown/) tags to switch the theme based on the user GitHub theme automatically. This is done by appending `#gh-dark-mode-only` or `#gh-light-mode-only` to the end of an image URL. This tag will define whether the image specified in the markdown is only shown to viewers using a light or a dark GitHub theme:
+
+```md
+[![Anurag's GitHub stats-Dark](https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true&theme=dark#gh-dark-mode-only)](https://github.com/anuraghazra/github-readme-stats#gh-dark-mode-only)
+[![Anurag's GitHub stats-Light](https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true&theme=default#gh-light-mode-only)](https://github.com/anuraghazra/github-readme-stats#gh-light-mode-only)
+```
+
+<details>
+<summary>:eyes: Show example</summary>
+
+[![Anurag's GitHub stats-Dark](https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true&theme=dark#gh-dark-mode-only)](https://github.com/anuraghazra/github-readme-stats#gh-dark-mode-only)
+[![Anurag's GitHub stats-Light](https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true&theme=default#gh-light-mode-only)](https://github.com/anuraghazra/github-readme-stats#gh-light-mode-only)
+
+</details>
+
+##### Use GitHub's new media feature
+
+You can use [GitHub's new media feature](https://github.blog/changelog/2022-05-19-specify-theme-context-for-images-in-markdown-beta/) in HTML to specify whether to display images for light or dark themes. This is done using the HTML `<picture>` element in combination with the `prefers-color-scheme` media feature.
+
+```html
+<picture>
+<source 
+  srcset="https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true&theme=dark"
+  media="(prefers-color-scheme: dark)"
+/>
+<source
+  srcset="https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true"
+  media="(prefers-color-scheme: light), (prefers-color-scheme: no-preference)"
+/>
+<img src="https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true" />
+</picture>
+```
+
+<details>
+<summary>:eyes: Show example</summary>
+
+<picture>
+<source 
+  srcset="https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true&theme=dark"
+  media="(prefers-color-scheme: dark)"
+/>
+<source
+  srcset="https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true"
+  media="(prefers-color-scheme: light), (prefers-color-scheme: no-preference)"
+/>
+<img src="https://github-readme-stats.vercel.app/api?username=anuraghazra&show_icons=true" />
+</picture>
+
+</details>
+
 ### Customization
 
 You can customize the appearance of your `Stats Card` or `Repo Card` however you wish with URL parameters.