Version: 2018.3
Properties types
The Event System

USS supported properties

This topic lists the supported USS properties and their accepted values.

USS syntax

UIElements style properties use the same grammar syntax as W3C CSS documents:

  • Keyword values appear as is. For example: auto, baseline.
  • Basic data types appear between angle brackets ( < and >). For example: <length>, <color>.
  • Non-terminals that share the same name as a property appear between angle brackets ( < and >). For example, <border-width>.

If a property value has more than one component:

  • Several juxtaposed words mean that all of them must occur, in the given order.
  • A bar (|) separates two or more alternatives: exactly one must occur.
  • A double bar (||) separates two or more options: one or more must occur, in any order.
  • A double ampersand (&&) separates two or more components, all of which must occur, in any order.
  • Square brackets ([ ]) denote grouping.

Every type, keyword, or angle-bracketed group may be followed by modifiers:

  • an asterisk (*) indicates that the preceding type, word, or group occurs zero or more times.
  • a plus (+) indicates that the preceding type, word, or group occurs one or more times.
  • a question mark (?) indicates that the preceding type, word, or group is optional.
  • a pair of numbers in curly braces ({A,B}) indicates that the preceding type, word, or group occurs at least A and at most B times.

Box model

Box model
Box model


  • width: <number>
  • height: <number>
  • min-width: <number>
  • min-height: <number>
  • max-width: <number>
  • max-height: <number>

The width and height specifies the size of the element in pixels. If width is not specified, the width is based on the width of the element’s contents. If height is not specified, the height is based on the height of the element’s contents.


  • margin-left: <number>
  • margin-top: <number>
  • margin-right: <number>
  • margin-bottom: <number>


  • border-left-width: <number>
  • border-top-width: <number>
  • border-right-width: <number>
  • border-bottom-width: <number>


  • padding-left: <number>
  • padding-top: <number>
  • padding-right: <number>
  • padding-bottom: <number>

Flex layout

This section lists the properties for positioning visual elements. UIElements includes a layout engine that positions visual elements based on layout and styling properties. The layout engine implements a subset of Flexbox: a HTML/CSS layout system.

By default, all items are vertically placed in their container.


  • flex-grow: <number>
  • flex-shrink: <number>
  • flex-basis: <number> | auto
  • flex: none | [ <flex-grow> [ <flex-shrink> <flex-basis>? ]? ]
  • align-self: auto | flex-start | flex-end | center | baseline | stretch

Note: Because units are not supported, the <flex-basis> value must always be specified last.


  • flex-direction: row | row-reverse | column | column-reverse
  • flex-wrap: nowrap | wrap | wrap-reverse
  • align-content: flex-start | flex-end | center | space-between | space-around | stretch
  • align-items: flex-start | flex-end | center | baseline | stretch
  • justify-content: flex-start | flex-end | center | space-between | space-around | space-evenly

Relative and absolute positioning


  • position: absolute | relative

This property is set to relative by default, which positions the element based on its parent. If this property is set to absolute, the element leaves its parent layout and values are specified based on the parent bounds.


  • left
  • top
  • right
  • bottom

The distance in pixels from the parent edge or the original position of the element.

Drawing properties

The drawing properties set the background, borders, and appearance of the visual element.


  • background-color: <color>
  • background-image: <resource> | <url> | none
  • -unity-background-scale-mode: stretch-to-fill | scale-and-crop | scale-to-fit


  • border-color: <color>
  • border-left-radius: <number>
  • border-top-radius: <number>
  • border-right-radius: <number>
  • border-bottom-radius: <number>


  • overflow: hidden | visible
  • opacity: <number>
  • visibility: visible | hidden

Text properties

Text properties set the color, font, font size, and Unity specific properties for font resource, font style, alignment, word wrap, and clipping.

  • color: <color>
  • -unity-font: <resource> | <url>
  • font-size: <number>
  • -unity-font-style: normal | italic | bold | bold-and-italic
  • -unity-text-align: upper-left | middle-left | lower-left | upper-left | middle-center | lower-center | upper-right | middle-right | lower-right
  • -unity-word-wrap: true | false
  • -unity-clipping: clip | overflow

Cursor property

Use the cursor default texture type to import a custom texture for the cursor. The Unity editor only supports default cursor values.

cursor: [ [ <resource> | <url> ][ <hotspotX> <hotspotY>]? , ][ arrow | text | resize-vertical | resize-horizontal | link | slide-arrow | resize-up-right | resize-up-left | move-arrow | rotate-arrow | scale-arrow | arrow-plus | arrow-minus | pan | orbit | zoom | fps | split-resize-up-down | split-resize-left-right ]

Obsolete and renamed properties

This section lists the drawing properties that were either made obsolete or renamed in UIElements. The obsolete and renamed properties are listed alphabetically.

  • background-size has been renamed -unity-background-scale-mode.
  • border-left, border-top, border-right, and border-bottom have been renamed border-left-width, border-top-width, border-right-width, and border-bottom-width, respectively.
  • font has been renamed -unity-font.
  • font-style has been renamed -unity-font-style.
  • position-left, position-top, position-right, and position-bottom have been renamed left, top, right, and bottom, respectively.
  • position-type has been renamed position.
  • text-alignment has been renamed -unity-text-align.
  • text-clipping has been renamed -unity-clipping. It is recommended that you use the standard overflow property instead.
  • text-color has been renamed color.
  • -word-wrap has been renamed -unity-word-wrap.

Properties types
The Event System