Describe variables for datagrid in docs

docs/ui/components/datagrid.mdx

@@ -88,3 +88,10 @@ description: Use the data grid component to display detailed information about y
   </div>
 </div>
 ```
+
+You can adjust the datagrid to your needs setting the values of variables:
+
+| Variable | Description | Default |
+|----------|-------------|---------|
+| `--tblr-datagrid-item-width` | Width of the datagrid item | `15rem` |
+| `--tblr-datagrid-padding` | Gap between the datagrid items | `1.5rem` |