Update logo file

Author: njucckevin

index.html

@@ -21,7 +21,7 @@
   <script src="./static/js/bulma-slider.min.js"></script>
   <script src="./static/js/index.js"></script>
 
-  <link rel="icon" href="./static/images/logo.png">
+  <link rel="icon" href="./static/images/logo_background.png">
 
   <script type="text/javascript" async src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.9/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
   <meta property="og:image:width" content="1600" />