Fixed issue : Left Side Back End Menu Design fix #18687

Author: suryakant-krish

app/design/adminhtml/Magento/backend/Magento_Backend/web/css/source/module/_menu.less

@@ -273,7 +273,16 @@
             > .submenu {
                 transform: translateX(0);
                 visibility: visible;
-                z-index: @submenu__z-index;
+                z-index: 698;
+                overflow-x: scroll;
+                min-height: 98.65%;
+                left: 0;
+                position: absolute;
+                left: 100%;
+                min-width: 100%;
+                display: block;
+                float: left;
+                max-width: 1640px;
             }
         }
     }