Version: Unity 6 Preview (6000.0)
Language : English
Descendant selectors
Multiple selectors

Child selectors

USS child selectors match elements that are the child 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.
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Syntax

A child selector consists of multiple simple selectors separated by >.

selector1 > selector2 {...}

You can include the wildcard selector in complex selectors. For example, the following USS rule uses the wildcard selector in a child selector. This USS rule matches buttons that are children of elements that are children of an element with the USS class yellow assigned to it.

.yellow > * > Button{..}

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
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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:

Example buttons with margins and thin blue borders.
Example buttons with margins and thin blue borders.

The following child selector style rule matches only the inner element. Element #OK, which has .yellow class, is a child of element #container2. #container2 is child of element #container1. Therefore, there is no direct descendant of #container1 that matches the .yellow selector.

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

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

The container2 has a yellow background color.
The container2 has a yellow background color.

Additional resources

Descendant selectors
Multiple selectors