Update darkmode README

Author: stevenjoezhang

.gitignore

@@ -1,2 +1,3 @@
 package-lock.json
 node_modules/
+.DS_Store

README.md

@@ -109,12 +109,24 @@ https://example.com/path/to/live2d-widget/
 
 ## 鸣谢 Thanks
 
-<a href="https://www.browserstack.com/"><img height="80" src="https://live.browserstack.com/images/opensource/browserstack-logo.svg" alt="BrowserStack Logo"></a>
+<a href="https://www.browserstack.com/">
+  <picture>
+    <source media="(prefers-color-scheme: dark)" height="80" srcset="https://d98b8t1nnulk5.cloudfront.net/production/images/layout/logo-header.png?1469004780">
+    <source media="(prefers-color-scheme: light)" height="80" srcset="https://live.browserstack.com/images/opensource/browserstack-logo.svg">
+    <img alt="BrowserStack Logo" height="80" src="https://live.browserstack.com/images/opensource/browserstack-logo.svg">
+  </picture>
+</a>
 
 > 感谢 BrowserStack 容许我们在真实的浏览器中测试此项目。  
 > Thanks to [BrowserStack](https://www.browserstack.com/) for providing the infrastructure that allows us to test in real browsers!
 
-<a href="https://www.jsdelivr.com"><img height="80" src="https://raw.githubusercontent.com/jsdelivr/jsdelivr-media/master/default/svg/jsdelivr-logo-horizontal.svg"></a>
+<a href="https://www.jsdelivr.com">
+  <picture>
+    <source media="(prefers-color-scheme: dark)" height="80" srcset="https://raw.githubusercontent.com/jsdelivr/jsdelivr-media/master/white/svg/jsdelivr-logo-horizontal.svg">
+    <source media="(prefers-color-scheme: light)" height="80" srcset="https://raw.githubusercontent.com/jsdelivr/jsdelivr-media/master/default/svg/jsdelivr-logo-horizontal.svg">
+    <img alt="jsDelivr Logo" height="80" src="https://raw.githubusercontent.com/jsdelivr/jsdelivr-media/master/default/svg/jsdelivr-logo-horizontal.svg">
+  </picture>
+</a>
 
 > 感谢 jsDelivr 提供的 CDN 服务。  
 > Thanks jsDelivr for providing public CDN service.