USS type selectors match elements based on their element types. USS type selectors are analogous to CSS type selectors that match HTML tags. For example, Button {...} in USS matches any Button elements in the same way that p {...} in CSS matches any paragraph (<p>) tag.
The following is the syntax for a type selector:
TypeName { ...}
When you write type selectors, specify only the concrete object type. Don’t include the namespace in the type name.
例如,这个选择器是有效的:
Button { ...}
This selector is invalid:
UnityEngine.UIElements.Button { ...}
To demonstrate how simple selectors match elements, here is an example UI 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 type selector style rule matches the two Button elements:
Button {
  border-radius: 8px;
  width: 100px;
  }
The UI looks like the following when you apply the style: