Theme Style Sheet (TSS) files are regular USS files. UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
See in Glossary Toolkit treats TSS as a distinct asset type and uses it for management purposes.
Regular USS syntax and format apply to TSS files, but usually, a theme file contains references to other USS files through the @import
rule.
Note: USS files also support the @import
rule.
You can create different TSS files for different themes and switch between them at runtime. Typically, you should use USS for styles. Consider TSS when you customize the look and feel for different platforms or devices, or when you use different fonts for different languages if your games or applications support multiple languages.
Note: When you add your first UIDocument to a GameObjectThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
See in Glossary in your project, it generates a default runtime theme asset at Assets/UI Toolkit/UnityThemes/UnityDefaultTheme.tss
. Although you can create a TSS from scratch, to get all the default UI controls to work, you must import the default runtime theme, and then overwrite or add new styles to create your custom theme.
To create a new TSS:
Create one or more USS files with your custom styles.
Do one of the following:
Import your style USS files to your theme.
Your custom theme also appears in the theme list of the ViewportThe user’s visible area of an app on their screen.
See in Glossary in UI Builder. To preview your theme, select it from the Viewport.
You can reference a TSS in UXML or C# the same way as you do with USS.
You can also set a TSS as the default theme for a Panel Setting asset. If you have more than one Panel Setting, each one can use a different TSS file.
Note: If you set a TSS for a Panel Setting asset, it doesn’t make the TSS a global style for the whole project. You still need to reference the TSS in UXML or C#.
You can use the TSS asset’s InspectorA Unity window that displays information about the currently selected GameObject, asset or project settings, allowing you to inspect and edit the values. More info
See in Glossary window or the @import
rule to import a theme.
Note: If you define the USS variables or styles in both the current TSS and the imported style sheet, the current TSS overrides the imported style sheet.
@import
ruleTo import the default Unity runtime theme, you must use the following syntax:
@import url("unity-theme://default");
Note: This URL in this syntax is a special case and it refers the built-in default theme inside the engine. You can’t use this syntax for any other themes.
@import
ruleTo import a theme other than the default theme, or a USS file, use the following syntax:
@import url("<path-to-file>/<file-name-with-extension>");
You can use a relative or an absolute path:
Assets
folder and begin with a /
or project://database/
. For example, /Assets/myFolder/myFile.uss
or project://database/Assets/myFolder/myFile.uss
./
. For example, ../myFolder/myFile.uss
.
Note: To reference a file from packages, use the absolute path of the package file that starts from the Packages
folder. For example, /Packages/com.unity.package.name/file-name.uss
or project://database/Packages/com.unity.package.name/file-name.uss
. you must use the format of com.unity.package.name
rather than package name
for the package name.