fix: z-index values

Author: abhishek97

sass/styles/components/sidenav.scss

@@ -5,7 +5,7 @@
   bottom: 0;
   left: 0;
   background-color: $black;
-  z-index: 15000;
+  z-index: 999;
   padding: {
     right: 0;
     left: 0;

sass/styles/components/topnav.scss

@@ -9,7 +9,7 @@
     left: 0;
   }
   border-bottom: solid 1px #eee;
-  z-index: 10000;
+  z-index: 998;
 
   ul {
     margin: unset;