Add button FX

Author: p0rtL6

index.html

@@ -59,6 +59,9 @@
         color: white;
         font-weight: 600;
       }
+      #button:hover {
+        filter: brightness(90%) contrast(150%);
+      }
       #instructions {
         font-size: 1em;
         margin-top: 0.5em;