Introduction to USS

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:

Style rules that include a selector and a declaration block.
Selectors that identify which visual element the style rule affects.
A declaration block, inside curly braces, that has one or more style declarations. Each style declaration has a property and a value. Each style declaration ends with a semi-colon.

语法

The following is the general syntax of a style rule:

selector {
  property1: value;
  property2: value;
}

样式与规则匹配

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;
}

支持的选择器类型

USS supports several types of simple and complex selectors that match elements based on different criteria, such as the following:

Element C# type name
指定的 name 属性
USS 类的列表
The element’s position in the visual tree and its relationship to other elements

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.

简单选择器

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.

复杂选择器

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.

其他资源

Style UI

USS 选择器

手册