Set bgcolor for space in fullscreen mode

In fullscreen mode with type: “space”, the outer space is gray for flat/air skins. However for e.g. web skin it is white. How can I set the outer space to be gray for web skin? Thanks.

You can use css as follows

<style>
  .webix_layout_space{
  	background: #ddd;
  }
</style>

http://webix.com/snippet/19e9510f