Introduction to USS built-in variables

USS built-in variables specify default values for Editor and runtime UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
See in Glossary. You can use these variables in your own USS to match your custom interfaces with Unity style.

The name of each built-in variable indicates how and where the variable is used. A variable name consists of one or more parts, separated by hyphens. Each part consists of one or more words separated by underscores.

--unity-{group}-{role_and_control}-{sub_element}-{pseudo_state_sequence}

Each part of the name shows the types of USS rules that use the variable.

• Group: The kind of data the variable represents.
• Role/Control: A conceptual grouping for the elements the variable affects.
• Sub-Element: An element or control the variable affects.
• Pseudo States: Lists the states Unity uses the variable for.

For example, the following variable name:

--unity-colors-button-text-hover

Provides the following information about how Unity uses the variable:

	Value	Meaning
Group	colors	Represents color data.
Role/Control	button	Affects buttons.
Sub-Element	text	Affects text. Its group is colors, so it affects text color.
Pseudo-States	hover	Applies to elements when the mouse pointer hovers over them.

This USS built-in variable changes the color of button text when a user hovers over the button.

Group

The group specifies what kind of data the variable represents. Each group has several possible sub-elements.

The variable names have the following groups:

Group	Used for
colors	Color properties, such as background-color and border-color
metrics	Properties that control dimensions and shapes. For example, border-radius, border-width, margin, and padding
icons	Standard Unity icon images

Role and Control

Roles and controls are two ways of grouping elements conceptually.

• Role refers to a group of elements that have the same purpose, regardless of what type each element is. For example, the error role includes all elements that display error messages to users.
• Control refers to a group of elements of the same type, regardless of what they do. For example, buttons includes all buttons in the Editor.

Each variable has either a role or a control.

The variable names have the following roles and controls:

Roles

Role	Description
default	Default style settings such as text color, background, and margin.
alternated_rows	Elements that display tabular data with alternating row colors. For example, list items in a list view.
error	Elements that communicate error states to users.
highlight	Highlighted parts of the UI. For example, text selections, or selected items in tree views.
link	Parts of the UI (typically text) that are clickable links. This is the un-clicked state.
play_mode	Elements displayed when the Editor is in Play mode.
visited_link	Parts of the UI, typically text, that are clickable links that a user has already clicked.
warning	Elements that communicate a warning message to users.

Controls

Control	Description
app_toolbar	The main Unity toolbarA row of buttons and basic controls at the top of the Unity Editor that allows you to interact with the Editor in various ways (e.g. scaling, translation). More info See in Glossary
app_toolbar_button	Buttons in the main Unity toolbar
box	Boxes used to group elements in the Editor UI
button	Buttons in the UI, except for toolbars
dropdown	Dropdown lists or menus
helpbox	Boxes used to display help information
input_field	Fields used to input text or numeric values
label	Text labels in the Editor UI
object_field	Fields used for object values. For example, property values for 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 or Asset.
popup	Popup menu and other popup controls
preview	Views used to display previews. For example, of Assets such as meshes and textures.
scrollbar_groove	The background element of a scrollbar in which users drag the scrollbar thumb
scrollbar_thumb	The draggable handle element in a scrollbar
slider_groove	The background element of a slider in which users drag the slider thumb
slider_thumb	The draggable handle element in a slider
slider_thumb_halo	An overlay displayed around the slider thumb when the user drags it
tab	Tab items in tab controls
toolbar	Any Editor toolbar except for the main Unity toolbar (app_toolbar)
toolbar_button	Buttons in an Editor toolbar
window	Editor windows

Sub-Element

The sub-element is the part of an element that the variable affects. Together with a variable’s group, the sub-element shows what kind of data the variable represents.

For example, when you see a variable name with the colors group and the text sub-element, it means Unity uses the variable in styles that affect text color.

The variable names have the following sub-elements:

Group	Sub-element	Description
colors
	background	An element’s background color
	border	An element’s outer border color
	border_accent	An element’s inner border color. For example, 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 windows have a two-tone border
	text	Text color for elements that display text
metrics
	margin_{left, top, right, bottom}	An element’s margin values
	padding_{left, top, right, bottom}	An element’s padding values
	border_{left, top, right, bottom}_width	An element’s border width values
	border_{left_top, left_bottom, right_top, right_bottom}_radius	An element’s border radius values values
	width, height	An element’s width and height values

Pseudo-States

The pseudo-state sequence is a list of UI states that Unity uses a variable for.

For example, when you see a variable name with the hover pseudo state, it means Unity uses the variable in styles that affect elements when a user hovers the pointer over them.

For example: --unity-colors-toolbar_button-text-hover.

A variable name can have more than one pseudo-state. Multiple pseudo states appear in alphabetical order, separated by underscores _.

For example: --unity-colors-toolbar_button-text-focus_selected.

Unity variable names can have any combination of the following pseudo-states:

Pseudo-state	Description
(none)	Normal state
checked	A checkbox-type control is checked
disabled	A control is disabled
focus	A control has focus
hover	A user hovers over a control
inactive	A control doesn’t have focus
pressed	A control is pressed
selected	A control is selected

Additional resources

• Create USS variables
• USS built-in variable reference