VisualElement includes style properties that set the dimensions of the element and how the element is drawn on screen, such as
Style properties are either set in C# or from a style sheet. Style properties are regrouped in their own data structure (
UIElements supports style sheets written in USS (Unity style sheet). USS files are text files inspired by Cascading Style Sheets (CSS) from HTML. The USS format is similar to CSS, but USS includes overrides and customizations to work better with Unity.
This section includes details on USS, its syntax, and its differences when compared to CSS.
The fundamental building blocks of a Unity style sheet (USS) are as follows :
The general syntax of a style rule is :
You can attach a Unity style sheet (USS) to any visual element. Style rules apply to the visual element and all of its descendants. Style sheets are also re-applied automatically when necessary.
StyleSheet objects with standard Unity APIs such as
Resources.Load(). Use the
VisualElement.styleSheets.Add() method to attach style sheets to visual elements.
If you modify a USS file while the
EditorWindow is running, style changes are applied immediately.
The process of style application is transparent to a developer using UIElements. Style sheets are re-applied automatically when needed (hierarchy changes, stylesheet reload).
Once a style sheet is defined, it can be applied to a UIElements tree of visual elements.
During this process, selectors are matched against elements to resolve which properties are applied from the USS file. If a selector matches an element, the style declarations are applied to the element.
For example, the following rule matches any
UIElements use the following criteria to match a visual element with its style rule:
name property that is a string
These traits can be used in selectors in the style sheet.
If you are familiar with CSS you can see the similarity with the HTML tag name, the
id attribute and