[FIX] website_portal: improve mobile layout

This commit closes odoo/odoo#19267

addons/website_portal/static/src/less/website_portal.less

@@ -15,4 +15,12 @@
         text-align: left;
     }
     table-layout: fixed;
-}
\ No newline at end of file
+
+    @media (max-width: @screen-xs-max) {
+        display: block;
+        width: 100%;
+        overflow-x: auto;
+        -webkit-overflow-scrolling: touch;
+        -ms-overflow-style: -ms-autohiding-scrollbar;
+    }
+}