Descendant selectors

USS descendant selectors match elements that are the descendant of another element in the visual treeAn object graph, made of lightweight nodes, that holds all the elements in a window or panel. It defines every UI you build with the UI Toolkit.
See in Glossary.

Syntax

A descendant selector consists of multiple simple selectors separated by a space:

selector1 selector2 {...}

Example

To demonstrate how simple selectors match elements, here is an example UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
See in Glossary Document.

<UXML xmlns="UnityEngine.UIElements">
  <VisualElement name="container1">
    <VisualElement name="container2" class="yellow">
      <Button name="OK" class="yellow" text="OK" />
      <Button name="Cancel" text="Cancel" />
    </VisualElement>
  </VisualElement>
</UXML>

With no styles applied, the UI looks like the following:

The following descendant selector style rule matches both the inner element and the first button.

#container1 .yellow {
  background-color: yellow;
}

The UI looks like the following when you apply the style:

Note: Heavy use of descendant selectors could negatively affect performance. For more performance guidelines, see Best practices for USS.

Additional resources

• Best practices for USS