A Unity Style Sheet (USS) is a text file recognized as an asset that supports style rules. The USS text file must have the .uss extension.
A USS consists of the following:
The following is the general syntax of a style rule:
selector {
property1: value;
property2: value;
}
When you define a style sheet, you can apply it to a visual tree. Selectors match against elements to resolve which properties apply from the USS file. If a selector matches an element, the style declarations apply to the element.
例如，以下规则匹配任何 Button 对象：
Button {
width: 200px;
}
USS supports several types of simple and complex selectors that match elements based on different criteria, such as the following:
name 属性USS also supports pseudo classes that you can use with selectors to target elements that are in a specific state or select the :root element.
If an element matches more than one selector, USS applies the styles from whichever selector takes precedence.
USS supports a set of simple selectors that are analogous, but not identical, to simple selectors in CSS. The following table provides a quick reference of USS simple selectors.
| Selector type | Syntax | Matches |
|---|---|---|
| Type selector | Type {...} |
Elements of a specific C# or visual element type. |
| Class selector | .class {...} |
Elements with an assigned USS class. |
| Name selector | #name {..} |
Elements with an assigned name attribute. |
| Universal selector | * {...} |
Any elements. |
USS supports a subset of CSS complex selectors. The following table provides a quick reference of USS complex selectors.
| Selector type | Syntax | Matches |
|---|---|---|
| Descendant selector | selector1 selector2 {...} |
Elements that are the descendant of another element in the visual tree. |
| Child selector | selector1 > selector2 {...} |
Elements that are the children of another element in the visual tree. |
| Multiple selector | selector1selector2 {...} |
Elements that match all the simple selectors. |