fix: z-index of main

src/styles/base/main.scss

@@ -18,6 +18,7 @@
 
   main {
     display: flex;
+    z-index: 0;
     overflow: hidden;
     height: calc(100vh - 83px); /* 83px = height of the header */
     position: relative;

src/styles/base/menu-left.scss

@@ -137,6 +137,7 @@
 
       sib-display.nosub>nav {
         text-align: center;
+        overflow: hidden;
         display: grid;
         grid-template-columns: auto 50% auto;
         grid-template-areas: "left middle right";