style: Add box shadow in code-block

Author: ktquez

styles/override/content.styl

@@ -14,6 +14,8 @@ div.theme-default-content
 
   div[class*=language-]
     background-color: var(--bg-code-block)
+    box-shadow: 6px 6px 0 #41b883;
+    border-radius: 0;
 
     .highlight-lines
       padding-top: 3.2rem