## GTK+ CSS

GTK+ CSS — GTK+ CSS Properties

## Supported CSS Properties

GTK+ supports CSS properties and shorthands as far as they can be applied in the context of widgets, and adds its own properties only when needed. All GTK+-specific properties have a -gtk prefix.

All properties support the following keywords: inherit, initial, unset, with the same meaning as in CSS.

The following basic datatypes are used throughout:

`〈length〉 = 〈number〉 [ px | pt | em | ex |rem | pc | in | cm | mm ] | 〈calc expression〉`
`〈percentage〉 = 〈number〉 % | 〈calc expression〉`
`〈angle〉 = 〈number〉 [ deg | grad | turn ] | 〈calc expression〉`
`〈time〉 = 〈number〉 [ s | ms ] | 〈calc expression〉`

Length values with the em or ex units are resolved using the font size value, unless they occur in setting the font-size itself, in which case they are resolved using the inherited font size value.

The rem unit is resolved using the initial font size value, which is not quite the same as the CSS definition of rem.

Whereever a number is allowed, GTK+ also accepts a Windows-specific theme size:

`〈win32 theme size〉 = 〈win32 size〉| 〈win32 part size〉`
`〈win32 size〉 = -gtk-win32-size ( 〈theme name〉, 〈metric id〉 )`
`〈win32 part size〉 = [ -gtk-win32-part-width | -gtk-win32-part-height |`
`-gtk-win32-part-border-top | -gtk-win32-part-border-right |`
`-gtk-win32-part-border-bottom | -gtk-win32-part-border-left ] ( 〈theme name〉 , 〈integer〉 , 〈integer〉 )`

`〈calc expression〉 = calc( 〈calc sum〉 )`
`〈calc sum〉 = 〈calc product〉 [ [ + | - ] 〈calc product〉 ]*`
`〈calc product〉 = 〈calc value〉 [ * 〈calc value〉 | / 〈number〉 ]*`
`〈calc value〉 = 〈number〉 | 〈length〉 | 〈percentage〉 | 〈angle〉 | 〈time〉 | ( 〈calc sum〉 )`

The calc() notation adds considerable expressive power. There are limits on what types can be combined in such an expression (e.g. it does not make sense to add a number and a time). For the full details, see the CSS3 Values and Units spec.

A common pattern among shorthand properties (called 'four sides') is one where one to four values can be specified, to determine a value for each side of an area. In this case, the specified values are interpreted as follows:

4 values: | top right bottom left
3 values: | top horizontal bottom
2 values: | vertical horizontal
1 value: | all

Table 2. Color Properties

Name | Value | Initial | Inh. | Ani. | Reference | Notes
--- | --- | --- | --- | --- | --- | ---
color | `〈color〉` | `rgba(1,1,1,1)` | ✓ | ✓ | CSS2, CSS3 |
opacity | `〈alpha value〉` | `1` |  | ✓ | CSS3 |

The color property specifies the color to use for text, icons and other foreground rendering. The opacity property specifies the opacity that is used to composite the widget onto its parent widget.

Table 3. Font Properties

Name | Value | Initial | Inh. | Ani. | Reference | Notes
--- | --- | --- | --- | --- | --- | ---
font‑family | `〈family name〉 [ , 〈family name〉 ]*` | gtk-font-name setting | ✓ |  | CSS2, CSS3 |
font‑size | `〈absolute size〉 | 〈relative size〉 | 〈length〉 | 〈percentage〉` | gtk-font-name setting | ✓ | ✓ | CSS2, CSS3 |
font‑style | `normal | oblique | italic` | `normal` | ✓ |  | CSS2, CSS3 |
font‑variant | `normal | small-caps` | `normal` | ✓ |  | CSS2, CSS3 | only CSS2 values supported
font‑weight | `normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900` | `normal` | ✓ | ✓ | CSS2, CSS3 | normal is synonymous with 400, bold with 700
font‑stretch | `ultra-condensed | extra-condensed | condensed | semi-condensed | normal | semi-expanded | expanded | extra-expanded | ultra-expanded` | `normal` | ✓ |  | CSS3 |
‑gtk‑dpi | `〈number〉` | screen resolution | ✓ | ✓ |  |

Shorthand | Value | Initial | Reference | Notes
--- | --- | --- | --- | ---
font | `[ 〈font-style〉 || 〈font-variant〉 || 〈font-weight〉 || 〈font-stretch〉 ]? 〈font-size〉 〈font-family〉` | see individual properties | CSS2, CSS3 | CSS allows line-height, etc

`〈absolute size〉 = xx-small | x-small | small | medium | large | x-large | xx-large`
`〈relative size〉 = larger | smaller`

The font properties determine the font to use for rendering text. Relative font sizes and weights are resolved relative to the inherited value for these properties.

Table 4. Text caret properties

Name | Value | Initial | Inh. | Ani. | Reference | Notes
--- | --- | --- | --- | --- | --- | ---
caret-color | `〈color〉` | `currentColor` | ✓ | ✓ | CSS3 | CSS allows an auto value
-gtk-secondary-caret-color | `〈color〉` | `currentColor` | ✓ | ✓ |  | Used for the secondary caret in bidirectional text

The caret properties provide a way to change the appearance of the insertion caret in editable text.

Table 5. Text decoration properties

Name | Value | Initial | Inh. | Ani. | Reference | Notes
--- | --- | --- | --- | --- | --- | ---
letter‑spacing | `〈length〉` | `0px` | ✓ | ✓ | CSS3 |
text‑decoration‑line | `none | underline | line-through` | `none` |  |  | CSS2, CSS3 | CSS allows overline
text‑decoration‑color | `〈color〉` | `currentColor` |  | ✓ | CSS3 |
text‑decoration‑style | `solid | double | wavy` | `solid` |  |  | CSS3 | CSS allows dashed and dotted
text‑shadow | `none | 〈shadow〉` | `none` | ✓ | ✓ | CSS3 |

Shorthand | Value | Initial | Reference | Notes
--- | --- | --- | --- | ---
text‑decoration | `〈text-decoration-line〉 || 〈text-decoration-style〉 || 〈text-decoration-color〉` | see individual properties | CSS3 |

`〈shadow〉 = 〈length〉 〈length〉 〈color〉?`

The text decoration properties determine whether to apply extra decorations when rendering text.

Table 6. Icon Properties

Name | Value | Initial | Inh. | Ani. | Reference | Notes
--- | --- | --- | --- | --- | --- | ---
‑gtk‑icon‑source | `builtin | 〈image〉 | none` | `builtin` |  | ✓ |  |
‑gtk‑icon‑transform | `none | 〈transform〉+` | `none` |  | ✓ |  |
‑gtk‑icon‑style | `requested | regular | symbolic` | `requested` | ✓ |  |  | Determines the preferred style for application-loaded icons
‑gtk‑icon‑theme | `〈name〉` | current icon theme | ✓ |  |  | The icon theme to use with -gtk-icontheme(). Since 3.20
‑gtk‑icon‑palette | `〈color palette〉` | `default` | ✓ | ✓ |  | Used to recolor symbolic icons (both application-loaded and from -gtk-icontheme()). Since 3.20
‑gtk‑icon‑shadow | `none | 〈shadow〉` | `none` | ✓ | ✓ |  |
‑gtk‑icon‑effect | `none | highlight | dim` | `none` | ✓ |  |  |

`〈transform〉 = matrix( 〈number〉 [ , 〈number〉 ]{5} ) | translate( 〈length〉, 〈length〉 ) | translateX( 〈length〉 ) | translateY( 〈length〉 ) |`
`scale( 〈number〉[ , 〈number〉 ]? ) | scaleX( 〈number〉 ) | scaleY( 〈number〉 ) | rotate( 〈angle〉 ) | skew( 〈angle〉 [ , 〈angle〉 ]? ) |`
`skewX( 〈angle〉 ) | skewY( 〈angle〉 )`
`〈color palette〉 = default | 〈name〉 〈color〉 [ , 〈name〉 〈color〉 ]*`

The -gtk-icon-source property is used by widgets that are rendering 'built-in' icons, such as arrows, expanders, spinners, checks or radios.

The -gtk-icon-style property determines the preferred style for application-provided icons.

The -gtk-icon-transform and -gtk-icon-shadow properties affect the rendering of both built-in and application-provided icons.

-gtk-icon-palette defines a color palette for recoloring symbolic icons. The recognized names for colors in symbolic icons are error, warning and success. The default palette maps these three names to symbolic colors with the names @error_color, @warning_color and @error_color.

Table 7. Box properties

Name | Value | Initial | Inh. | Ani. | Reference | Notes
--- | --- | --- | --- | --- | --- | ---
min‑width | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 | CSS allows percentages
min‑height | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 | CSS allows percentages
margin‑top | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 | CSS allows percentages or auto
margin‑right | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 | CSS allows percentages or auto
margin‑bottom | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 | CSS allows percentages or auto
margin‑left | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 | CSS allows percentages or auto
padding‑top | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 | CSS allows percentages
padding‑right | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 | CSS allows percentages
padding‑bottom | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 | CSS allows percentages
padding‑left | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 | CSS allows percentages

Shorthand | Value | Initial | Reference | Notes
--- | --- | --- | --- | ---
margin | `〈length〉{1,4}` | see individual properties | CSS2, CSS3 | a 'four sides' shorthand
padding | `〈length〉{1,4}` | see individual properties | CSS2, CSS3 | a 'four sides' shorthand

Table 8. Border properties

Name | Value | Initial | Inh. | Ani. | Reference | Notes
--- | --- | --- | --- | --- | --- | ---
border‑top‑width | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 | CSS allows other values
border‑right‑width | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 | CSS allows other values
border‑bottom‑width | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 | CSS allows other values
border‑right‑width | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 | CSS allows other values
border‑top‑style | `〈border style〉` | `none` |  |  | CSS2, CSS3 |
border‑right‑style | `〈border style〉` | `none` |  |  | CSS2, CSS3 |
border‑bottom‑style | `〈border style〉` | `none` |  |  | CSS2, CSS3 |
border‑left‑style | `〈border style〉` | `none` |  |  | CSS2, CSS3 |
border‑top‑right‑radius | `〈corner radius〉` | `0` |  | ✓ | CSS2, CSS3 |
border‑bottom‑right‑radius | `〈corner radius〉` | `0` |  | ✓ | CSS2, CSS3 |
border‑bottom‑left‑radius | `〈corner radius〉` | `0` |  | ✓ | CSS2, CSS3 |
border‑top‑left‑radius | `〈corner radius〉` | `0` |  | ✓ | CSS2, CSS3 |
border‑top‑color | `〈color〉` | `currentColor` |  | ✓ | CSS2, CSS3 |
border‑right‑color | `〈color〉` | `currentColor` |  | ✓ | CSS2, CSS3 |
border‑bottom‑color | `〈color〉` | `currentColor` |  | ✓ | CSS2, CSS3 |
border‑left‑color | `〈color〉` | `currentColor` |  | ✓ | CSS2, CSS3 |
border‑image‑source | `〈image〉 | none` | `none` |  | ✓ | CSS3 |
border‑image‑repeat | `〈border repeat〉{1,2}` | `stretch` |  |  | CSS3 |
border‑image‑slice | `[ 〈number〉 | 〈percentage〉 ]{1,4} && fill?` | `100%` |  |  | CSS3 | a 'four sides' shorthand
border‑image‑width | `[ 〈length〉 | 〈number〉 | 〈percentage〉 | auto ]{1,4}` | `1` |  |  | CSS3 | a 'four sides' shorthand

Shorthand | Value | Initial | Reference | Notes
--- | --- | --- | --- | ---
border‑width | `〈length〉{1,4}` | see individual properties | CSS2, CSS3 | a 'four sides' shorthand
border‑style | `〈border style〉{1,4}` | see individual properties | CSS2, CSS3 | a 'four sides' shorthand
border‑color | `〈color〉{1,4}` | see individual properties | CSS3 | a 'four sides' shorthand
border‑top | `〈length〉 || 〈border style〉 || 〈color〉` | see individual properties | CSS2, CSS3 |
border‑left | `〈length〉 || 〈border style〉 || 〈color〉` | see individual properties | CSS2, CSS3 |
border‑bottom | `〈length〉 || 〈border style〉 || 〈color〉` | see individual properties | CSS2, CSS3 |
border‑right | `〈length〉 || 〈border style〉 || 〈color〉` | see individual properties | CSS2, CSS3 |
border | `〈length〉 || 〈border style〉 || 〈color〉` | see individual properties | CSS2, CSS3 |
border‑radius | `[ 〈length〉 | 〈percentage〉 ]{1,4} [ / [ 〈length〉 | 〈percentage> ]{1,4} ]?` | see individual properties | CSS3 |
border‑image | `〈border-image-source〉 || 〈border-image-slice〉 [ / 〈border-image-width〉 | / 〈border-image-width〉? / 〈border-image-outset〉 ]? || 〈border-image-repeat〉` | see individual properties | CSS3 |

`〈border style〉 = none | solid | inset | outset | hidden | dotted | dashed | double | groove | ridge`
`〈corner radius〉 = [ 〈length〉 | 〈percentage〉 ]{1,2}`

Table 9. Outline properties

Name | Value | Initial | Inh. | Ani. | Reference | Notes
--- | --- | --- | --- | --- | --- | ---
outline‑style | `none | solid | inset | outset | hidden | dotted | dashed | double | groove | ridge` | `none` |  |  | CSS2, CSS3 |
outline‑width | `〈length〉` | `0px` |  | ✓ | CSS2, CSS3 |
outline‑color | `〈color〉` | `currentColor` |  | ✓ | CSS2, CSS3 |
outline‑offset | `〈length〉` | `0px` |  |  | CSS3 |
‑gtk‑outline‑top‑left‑radius | `〈corner radius〉` | `0` |  | ✓ |  |
‑gtk‑outline‑top‑right‑radius | `〈corner radius〉` | `0` |  | ✓ |  |
‑gtk‑outline‑bottom‑right‑radius | `〈corner radius〉` | `0` |  | ✓ |  |
‑gtk‑outline‑bottom‑left‑radius | `〈corner radius〉` | `0` |  | ✓ |  |

Shorthand | Value | Initial | Reference | Notes
--- | --- | --- | --- | ---
outline | `〈outline-color〉 || 〈outline-style〉 || 〈outline-width〉` | see individual properties | CSS2, CSS3 |
‑gtk‑outline‑radius | `[ 〈length〉|〈percentage〉 ]{1,4} [ / [〈length〉 | 〈percentage> ]{1,4} ]?` | see individual properties |  |

GTK+ uses the CSS outline properties to render the 'focus rectangle'.

Table 10. Background properties

Name | Value | Initial | Inh. | Ani. | Reference | Notes
--- | --- | --- | --- | --- | --- | ---
background‑color | `〈color〉` | `rgba(0,0,0,0)` |  | ✓ | CSS2, CSS3 |
background‑clip | `〈box〉 [ , 〈box〉 ]*` | `border-box` |  |  | CSS3 |
background‑origin | `〈box〉 [ , 〈box〉 ]*` | `padding-box` |  |  | CSS3 |
background‑size | `〈bg-size〉 [ , 〈bg-size〉 ]*` | `auto` |  | ✓ | CSS3 |
background‑position | `〈position〉 [ , 〈position〉 ]*` | `0` |  | ✓ | CSS2, CSS3 |
background‑repeat | `〈bg-repeat 〉[ , 〈bg-repeat〉 ]*` | `repeat` |  |  | CSS2, CSS3 |
background‑image | `〈bg-image〉[ , 〈bg-image〉 ]*` | `none` |  | ✓ | CSS2, CSS3 | not supported: urls without quotes, CSS radial gradients, colors in crossfades
background-blend-mode | `〈blend-mode〉 [ , 〈blend-mode〉 ]*` | `normal` |  |  |  | only affects multiple backgrounds
box‑shadow | `none | 〈box shadow〉 [ , 〈box shadow〉 ]*` | `none` |  | ✓ | CSS3 |

Shorthand | Value | Initial | Reference | Notes
--- | --- | --- | --- | ---
background | `[ 〈bg-layer〉 , ]* 〈final-bg-layer〉` | see individual properties | CSS2, CSS3 |

`〈box〉 = border-box | padding-box | content-box`
`〈bg-size〉 = [ 〈length〉 | 〈percentage〉 | auto ]{1,2} | cover | contain`
`〈position〉 = [ left | right | center | top | bottom | 〈percentage〉 | 〈length〉 ]{1,2,3,4}`
`〈bg-repeat〉 = repeat-x | repeat-y | [ no-repeat | repeat | round | space ]{1,2}`
`〈bg-image〉 = 〈image〉 | none`
`〈bg-layer〉 = 〈bg-image〉 || 〈position〉 [ / 〈bg-size〉 ]? || 〈bg-repeat〉 || 〈box〉 || 〈box〉`
`〈final-bg-layer〉 = 〈bg-image〉 || 〈position〉 [ / 〈bg-size〉 ]? || 〈bg-repeat〉 || 〈box〉 || 〈box〉|| 〈color〉`
`〈blend-mode〉 = color || color-burn || color-dodge || darken || difference || exclusion || hard-light || hue || lighten || luminosity || multiply || normal || overlay || saturate || screen || soft-light`
`〈box shadow〉 = inset? && 〈length〉{2,4}? && 〈color〉?`

As in CSS, the background color is rendered underneath all the background image layers, so it will only be visible if background images are absent or have transparency.

Alternatively, multiple backgrounds can be blended using the `background-blend-mode` property.

Table 11. Transition properties

Name | Value | Initial | Inh. | Ani. | Reference | Notes
--- | --- | --- | --- | --- | --- | ---
transition‑property | `none | all | 〈property name〉 [ , 〈property name〉 ]*` | `all` |  |  | CSS3 |
transition‑duration | `〈time〉 [ , 〈time〉 ]*` | `0s` |  |  | CSS3 |
transition‑timing‑function | `〈single‑timing‑function〉[ , 〈single‑timing‑function〉 ]*` | `ease` |  |  | CSS3 |
transition‑delay | `〈time〉 [ , 〈time〉 ]*` | `0s` |  |  | CSS3 |

Shorthand | Value | Initial | Reference | Notes
--- | --- | --- | --- | ---
transition | `〈single-transition〉 [ , 〈single-transition〉 ]*` | see individual properties | CSS3 |

`〈single-timing-function〉 = ease | linear | ease-in | ease-out | ease-in-out |`
`step-start | step-end | steps( 〈integer〉 [ , [ start | end ] ]? ) |`
`cubic-bezier( 〈number〉, 〈number〉, 〈number〉, 〈number〉 )`
`〈single-transition〉 = [ none | 〈property name〉 ] || 〈time〉 || 〈single-transition-timing-function〉 || 〈time〉`

Table 12. Animation properties

Name | Value | Initial | Inh. | Ani. | Reference | Notes
--- | --- | --- | --- | --- | --- | ---
animation‑name | `〈single-animation-name〉 [ , 〈single-animation-name〉 ]*` | `none` |  |  | CSS3 |
animation‑duration | `〈time〉 [ , 〈time〉 ]*` | `0s` |  |  | CSS3 |
animation‑timing‑function | `〈single‑timing‑function〉 [ , 〈single‑timing‑function〉 ]*` | `ease` |  |  | CSS3 |
animation‑iteration-count | `〈single‑animation‑iteration‑count〉 [ , 〈single‑animation‑iteration‑count〉 ]*` | `1` |  |  | CSS3 |
animation‑direction | `〈single‑animation‑direction〉 [ , 〈single‑animation‑direction〉 ]*` | `normal` |  |  | CSS3 |
animation‑play‑state | `〈single‑animation‑play‑state〉 [ , 〈single‑animation‑play‑state〉 ]*` | `running` |  |  | CSS3 |
animation‑delay | `〈time〉 [ , 〈time〉 ]*` | `0s` |  |  | CSS3 |
animation‑fill‑mode | `〈single‑animation‑fill‑mode〉 [ , 〈single‑animation‑fill‑mode〉 ]*` | `none` |  |  | CSS3 |

Shorthand | Value | Initial | Reference | Notes
--- | --- | --- | --- | ---
animation | `〈single‑animation〉 [ , 〈single‑animation〉]*` | see individual properties | CSS3 |

`〈single-animation-name〉 = none | 〈property name〉`
`〈single-animation-iteration-count〉 = infinite | 〈number〉`
`〈single-animation-direction〉 = normal | reverse | alternate | alternate-reverse`
`〈single-animation-play-state〉 = running | paused`
`〈single-animation-fill-mode〉 = none | forwards | backwards | both`
`〈single-animation〉 = 〈single-animation-name〉 || 〈time〉 || 〈single-timing-function〉 || 〈time〉 ||`
`〈single-animation-iteration-count〉 || 〈single-animation-direction〉 || 〈single-animation-play-state〉 || 〈single-animation-fill-mode〉`

Table 13. Key binding properties

Name | Value | Initial | Inh. | Ani. | Reference | Notes
--- | --- | --- | --- | --- | --- | ---
‑gtk‑key‑bindings | `none | 〈binding name〉 [ , 〈binding name〉 ]*` | `none` |  |  |  |

〈binding name〉 must have been assigned to a binding set with a @binding-set rule.