[wip] Left line for row hover

But it's not perfect. Can we use a pseudo element instead?

app/webpacker/css/admin/products_v3.scss

@@ -20,14 +20,17 @@
     table-layout: fixed; // Column widths are based solely on col definitions (not content). This allows more efficient rendering.
 
     background-color: $color-tbl-bg;
-    padding: 4px;
+    padding: 4px 4px 4px 0; // Left border is implemented in td:first-child
     border-collapse: separate; // This is needed for the outer padding. Also should be helpful to give more flexibility of borders between rows.
 
     // Row hover
     tr:hover {
-      th,
       td {
         background-color: $light-grey;
+
+        &:first-child {
+          border-left-color: $teal;
+        }
       }
     }
 
@@ -35,6 +38,11 @@
     td {
       padding: $padding-tbl-cell;
       border: none;
+
+      &:first-child {
+        // Implement the
+        border-left: 4px solid $color-tbl-bg;
+      }
     }
 
     th {