GTK+ CSS 3 GTK Library GTK+ CSS Overview of CSS in GTK+ This chapter describes in detail how GTK+ uses CSS for styling and layout. We loosely follow the CSS value definition specification in the formatting of syntax productions. Nonterminals are enclosed in angle backets (〈〉), all other strings that are not listed here are literals Juxtaposition means all components must occur, in the given order A double ampersand (&&) means all components must occur, in any order A double bar (||) means one or more of the components must occur, in any order A single bar (|) indicates an alternative; exactly one of the components must occur Brackets ([]) are used for grouping A question mark (?) means that the preceding component is optional An asterisk (*) means zero or more copies of the preceding component A plus (+) means one or more copies of the preceding component A number in curly braces ({n}) means that the preceding component occurs exactly n times Two numbers in curly braces ({m,n}) mean that the preceding component occurs at least m times and at most n times GTK+ applies the style information found in style sheets by matching the selectors against a tree of nodes. Each node in the tree has a name, a state and possibly style classes. The children of each node are linearly ordered. Every widget has one or more of these CSS nodes, and determines their name, state, style classes and how they are layed out as children and siblings in the overall node tree. The documentation for each widget explains what CSS nodes it has. The basic structure of the style sheets understood by GTK+ is a series of statements, which are either rule sets or “@-rules”, separated by whitespace. A rule set consists of a selector and a declaration block, which is a series of declarations enclosed in curly braces. The declarations are separated by semicolons. Multiple selectors can share the same declaration block, by putting all the separators in front of the block, separated by commas. GTK+ supports the CSS @import rule, in order to load another style sheet in addition to the currently parsed one. The syntax for @import rules is as follows: 〈import rule〉 = @import [ 〈url〉 | 〈string〉] ; 〈url〉 = url( 〈string〉) To learn more about the @import rule, you can read the Cascading module of the CSS specification. Selectors work very similar to the way they do in CSS. Typically widgets have one or more CSS nodes with element names (GTK+ falls back to using the widget type if a widget has no element name) and style classes. When style classes are used in selectors, they have to be prefixed with a period. Widget names can be used in selectors like IDs. When used in a selector, widget names must be prefixed with a # character. In more complicated situations, selectors can be combined in various ways. To require that a node satisfies several conditions, combine several selectors into one by concatenating them. To only match a node when it occurs inside some other node, write the two selectors after each other, separated by whitespace. To restrict the match to direct children of the parent node, insert a > character between the two selectors. entry { color: @fg_color; background-color: #1209a2 } ]]> It is possible to select CSS nodes depending on their position amongst their siblings by applying pseudo-classes to the selector, like :first-child, :last-child or :nth-child(even). When used in selectors, pseudo-classes must be prefixed with a : character. Another use of pseudo-classes is to match widgets depending on their state. The available pseudo-classes for widget states are :active, :hover :disabled, :selected, :focus, :indeterminate, :checked and :backdrop. In addition, the following pseudo-classes don't have a direct equivalent as a widget state: :dir(ltr) and :dir(rtl) (for text direction), :link and :visited (for links) and :drop(active) (for highlighting drop targets). Widget state pseudo-classes may only apply to the last element in a selector. To determine the effective style for a widget, all the matching rule sets are merged. As in CSS, rules apply by specificity, so the rules whose selectors more closely match a node will take precedence over the others. The full syntax for selectors understood by GTK+ can be found in the table below. The main difference to CSS is that GTK+ does not currently support attribute selectors. PatternMatchesReferenceNotes * any node CSS E any node with name E CSS GTK+ uses the type name of the widget if no CSS name has been set E.class any E node with the given style class CSS E#id any E node with the given ID CSS GTK+ uses the widget name as ID E:nth‑child(〈nth‑child〉) any E node which is the n-th child of its parent node CSS E:nth‑last‑child(〈nth‑child〉) any E node which is the n-th child of its parent node, counting from the end CSS E:first‑child any E node which is the first child of its parent node CSS E:last‑child any E node which is the last child of its parent node CSS E:only‑child any E node which is the only child of its parent node CSS Equivalent to E:first-child:last-child E:link, E:visited any E node which represents a hyperlink, not yet visited (:link) or already visited (:visited) CSS Corresponds to GTK_STATE_FLAG_LINK and GTK_STATE_FLAGS_VISITED E:active, E:hover, E:focus any E node which is part of a widget with the corresponding state CSS Corresponds to GTK_STATE_FLAG_ACTIVE, GTK_STATE_FLAG_PRELIGHT and GTK_STATE_FLAGS_FOCUSED; GTK+ also allows E:prelight and E:focused E:disabled any E node which is part of a widget with is disabled CSS Corresponds to GTK_STATE_FLAG_INSENSITIVE; GTK+ also allows E:insensitive E:checked any E node which is part of a widget (e.g. radio- or checkbuttons) which is checked CSS Corresponds to GTK_STATE_FLAG_CHECKED E:indeterminate any E node which is part of a widget (e.g. radio- or checkbuttons) which is in an inconsistent state CSS3, CSS4 Corresponds to GTK_STATE_FLAG_INCONSISTENT; GTK+ also allows E:inconsistent E:backdrop, E:selected any E node which is part of a widget with the corresponding state Corresponds to GTK_STATE_FLAG_BACKDROP, GTK_STATE_FLAG_SELECTED E:not(〈selector〉) any E node which does not match the simple selector 〈selector〉 CSS E:dir(ltr), E:dir(rtl) any E node that has the corresponding text direction CSS4 E:drop(active) any E node that is an active drop target for a current DND operation CSS4 E F any F node which is a descendent of an E node CSS E > F any F node which is a child of an E node CSS E ~ F any F node which is preceded by an E node CSS E + F any F node which is immediately preceded by an E node CSS 〈nth-child〉 = even | odd | 〈integer〉 | 〈integer〉n | 〈integer〉n [ + | - ] 〈integer〉 To learn more about selectors in CSS, read the Selectors module of the CSS specification. CSS allows to specify colors in various ways, using numeric values or names from a predefined list of colors. 〈color〉 = currentColor | transparent | 〈color name〉 | 〈rgb color〉 | 〈rgba color〉 | 〈hex color〉 | 〈gtk color〉 〈rgb color 〉 = rgb( 〈number〉, 〈number〉, 〈number〉 ) | rgb( 〈percentage〉, 〈percentage〉, 〈percentage〉 ) 〈rgba color 〉 = rgba(〈number〉, 〈number〉, 〈number〉, 〈alpha value〉) | rgba( 〈percentage〉, 〈percentage〉, 〈percentage〉, 〈alpha value〉 ) 〈hex color〉 = #〈hex digits〉 〈alpha value〉 = 〈number〉, clamped to values between 0 and 1. The keyword currentColor resolves to the current value of the color property when used in another property, and to the inherited value of the color property when used in the color property itself. The keyword transparent can be considered a shorthand for rgba(0,0,0,0). For a list of valid color names and for more background on colors in CSS, see the Color module of the CSS specification. GTK+ adds several additional ways to specify colors. 〈gtk color〉 = 〈symbolic color〉 | 〈color expression〉| 〈win32 color〉 The first is a reference to a color defined via a @define-color rule. The syntax for @define-color rules is as follows: 〈define color rule〉 = @define-color 〈name〉 〈color〉 To refer to the color defined by a @define-color rule, use the name from the rule, prefixed with @. 〈symbolic color〉 = @〈name〉 GTK+ also allows to form color expressions, which can be nested and provide a rich language to define colors which are derived from a set of base colors. 〈color expression〉 = ligher(〈color〉) | darker(〈color〉) | shade(〈number〉,〈color〉) | alpha(〈number〉,〈color〉) | mix(〈number〉,〈color〉,〈color〉) On Windows, GTK+ allows to refer to system colors, as follows: 〈win32 color〉 = -gtk-win32-color( 〈name〉, 〈integer〉) CSS allows to specify images in various ways, for backgrounds and borders. 〈image〉 = 〈url〉 | 〈crossfade〉 | 〈gradient〉 | 〈gtk image〉 〈crossfade〉 = cross-fade( 〈percentage〉, 〈image〉, 〈image〉) 〈gradient〉 = [ linear-gradient | repeating-linear-gradient ] ( [ [ 〈angle〉 | to 〈side or corner〉 ] , ]? 〈color stop〉 [ , 〈color stop〉]+ ) 〈side or corner〉 = [ left | right ] || [ top | bottom ] 〈color stop〉 = 〈color〉 [ 〈percentage〉 | 〈length〉 ]? The simplest way to specify an image in CSS is to load an image file from a URL. CSS does not specify anything about supported file formats; within GTK+, you can expect at least PNG, JPEG and SVG to work. The full list of supported image formats is determined by the available gdk-pixbuf image loaders and may vary between systems. A crossfade lets you specify an image as an intermediate between two images. Crossfades are specified in the draft of the level 4 Image module of the CSS specification. Gradients are images that smoothly fades from one color to another. CSS provides ways to specify repeating and non-repeating linear and radial gradients. GTK+ currently only supports linear gradients in the CSS syntax, but see the -gtk-gradient extension below, which does allow to specify radial gradients as well. A linear gradient is created by specifying a gradient line and then several colors placed along that line. The gradient line may be specified using an angle, or by using direction keywords. To learn more about gradients in CSS, including details of how color stops are placed on the gradient line, you can read the Image module of the CSS specification. GTK+ extends the CSS syntax for images and also uses it for specifying icons. 〈gtk image〉 = 〈gtk gradient〉 | 〈themed icon〉 | 〈scaled image〉 | 〈win32 theme part〉 GTK+ supports an alternative syntax for linear and radial gradients (which was implemented before CSS gradients were supported). 〈gtk gradient〉 = 〈gtk linear gradient〉 | 〈gtk radial gradient〉 〈gtk linear gradient〉 = -gtk-gradient(linear, [ 〈x position〉 〈y position〉 , ]{2} 〈gtk color stop〉 [ , 〈gtk color stop〉 ]+ ) 〈gtk radial gradient〉 = -gtk-gradient(radial, [ 〈x position〉 〈y position〉 , 〈radius〉 , ]{2} 〈gtk color stop〉 [ , 〈gtk color stop〉 ]+ ) 〈x position〉 = left | right | center | 〈number〉 〈y position〉 = top | bottom | center | 〈number〉 〈radius 〉 = 〈number〉 〈gtk color stop〉 = color-stop( 〈number〉 , 〈color〉 ) | from( 〈color〉 ) | to( 〈color〉 ) The numbers used to specify x and y positions, radii, as well as the positions of color stops, must be between 0 and 1. The keywords for for x and y positions (left, right, top, bottom, center), map to numeric values of 0, 1 and 0.5 in the obvious way. Color stops using the from() and to() syntax are abbreviations for color-stop with numeric positions of 0 and 1, respectively. GTK+ has extensive support for loading icons from icon themes. It is accessible from CSS with the -gtk-icontheme syntax. 〈themed icon〉 = -gtk-icontheme( 〈icon name〉 ) The specified icon name is used to look up a themed icon, while taking the values of the -gtk-icon-style and -gtk-icon-theme properties. This kind of image is mainly used as value of the -gtk-icon-source property. GTK+ supports scaled rendering on hi-resolution displays. This works best if images can be specify normal and hi-resolution variants. From CSS, this can be done with the -gtk-scaled syntax. 〈scaled image〉 = -gtk-scaled( 〈image〉[, 〈image〉]* ) While -gtk-scaled accepts multiple higher-resolution variants, in practice, it will mostly be used to specify a regular image and one variant for scale 2. On Windows, GTK+ allows to refer to system theme parts as images, as follows: 〈win32 theme part〉 = -gtk-win32-theme-part( 〈name〉, 〈integer〉 〈integer〉 [, [ over( 〈integer〉 〈integer〉 [ , 〈alpha value〉]? ) | margins( 〈integer〉{1,4} ) ] ]* ) CSS defines a mechanism by which changes in CSS property values can be made to take effect gradually, instead of all at once. GTK+ supports these transitions as well. To enable a transition for a property when a rule set takes effect, it needs to be listed in the transition-property property in that rule set. Only animatable properties can be listed in the transition-property. The details of a transition can modified with the transition-duration, transition-timing-function and transition-delay properties. To learn more about transitions, you can read the Transitions module of the CSS specification. In addition to transitions, which are triggered by changes of the underlying node tree, CSS also supports defined animations. While transitions specify how property values change from one value to a new value, animations explicitly define intermediate property values in keyframes. Keyframes are defined with an @-rule which contains one or more of rule sets with special selectors. Property declarations for nonanimatable properties are ignored in these rule sets (with the exception of animation properties). 〈keyframe rule〉 = @keyframes 〈name〉 { 〈animation rule〉 } 〈animation rule〉 = 〈animation selector〉 { 〈declaration〉* } 〈animation selector〉 = 〈single animation selector〉 [ , 〈single animation selector ]* 〈single animation selector〉 = from | to | 〈percentage〉 To enable an animation, the name of the keyframes must be set as the value of the animation-name property. The details of the animation can modified with the animation-time, animation-timing-function, animation-iteration-count and other animation properties. To learn more about animations, you can read the Animations module of the CSS specification. In order to extend key bindings affecting different widgets, GTK+ supports the @binding-set rule to parse a set of bind/unbind directives. Note that in order to take effect, the binding sets defined in this way must be associated with rule sets by setting the -gtk-key-bindings property. The syntax for @binding-set rules is as follows: 〈binding set rule〉 = @binding-set 〈binding name〉{ [ [ 〈binding〉 | 〈unbinding〉] ; ]* } 〈binding〉 = bind "〈accelerator〉" { 〈signal emission〉* } 〈signal emission〉 = "〈signal name〉" ( [ 〈argument〉[ , 〈argument〉]* ]? } 〈unbinding〉 = unbind "〈accelerator〉" ; where 〈accelerator〉 is a string that can be parsed by gtk_accelerator_parse(), 〈signal name〉 is the name of a keybinding signal of the widget in question, and the 〈argument〉 list must be according to the signals declaration. Left" { "move-cursor" (visual-positions, -3, 0) }; unbind "End"; }; @binding-set binding-set2 { bind "Right" { "move-cursor" (visual-positions, 3, 0) }; bind "KP_space" { "delete-from-cursor" (whitespace, 1) "insert-at-cursor" (" ") }; }; entry { -gtk-key-bindings: binding-set1, binding-set2; } ]]> GTK+ supports CSS properties and shorthands as far as they can be applied in the context of widgets, and only adds its own properties only when needed. All GTK+-specific properties have a -gtk prefix. All properties support the following keywords: inherit, initial, unset. The following basic datatypes are used throughout: 〈length〉 = 〈number〉 [ px | pt | em | ex | pc | in | cm | mm ] 〈percentage〉 = 〈number〉 % 〈angle〉 = 〈number〉 [ deg | grad | turn ] 〈time〉 = 〈number〉 [ s | ms ] 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. 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 left 2 values:vertical horizontal 1 value:all NameValueInitialInh.Ani.ReferenceNotes 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. NameValueInitialInh.Ani.ReferenceNotes 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 ✓ ✓ ShorthandValueInitialReferenceNotes 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. NameValueInitialInh.Ani.ReferenceNotes 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 ShorthandValueInitialReferenceNotes 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. NameValueInitialInh.Ani.ReferenceNotes ‑gtk‑icon‑source builtin | 〈image〉 | none builtin ✓ ‑gtk‑icon‑transform none | 〈transform〉+ none ✓ ‑gtk‑icon‑style requested | regular | symbolic requested ✓ ‑gtk‑icon‑theme 〈name〉 current icon theme ✓ Since 3.20 ‑gtk‑icon‑palette default | 〈name〉 〈color〉 [ , 〈name〉 〈color〉 ]* default ✓ ✓ 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〉 ) The icon properties are used by widgets that are rendering 'icons', such as arrows, expanders, spinners, checks or radios. -gtk-icon-style and -gtk-icon-theme are used when resolving images using the -gtk-icontheme syntax. -gtk-icon-palette defines a color palette for recoloring symbolic icons. The recognized names for colors in symbolic icons are "error", "warning" and "success". NameValueInitialInh.Ani.ReferenceNotes 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 ShorthandValueInitialReferenceNotes 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 NameValueInitialInh.Ani.ReferenceNotes 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 ShorthandValueInitialReferenceNotes 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 see individual properties CSS3 〈border style〉 = none | solid | inset | outset | hidden | dotted | dashed | double | groove | ridge 〈corner radius〉 = [ 〈length〉 | 〈percentage〉 ]{1,2} NameValueInitialInh.Ani.ReferenceNotes 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 ✓ ShorthandValueInitialReferenceNotes 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 NameValueInitialInh.Ani.ReferenceNotes 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 box‑shadow none | 〈box shadow〉 [ , 〈box shadow〉 ]* none ✓ CSS3 ShorthandValueInitialReferenceNotes 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〉 〈box shadow〉 = inset? && 〈length〉{2,4}? && 〈color〉? NameValueInitialInh.Ani.ReferenceNotes 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 ShorthandValueInitialReferenceNotes 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〉 NameValueInitialInh.Ani.ReferenceNotes 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 ShorthandValueInitialReferenceNotes animation 〈single‑animation〉 [ , 〈single‑animation〉]* 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〉 NameValueInitialInh.Ani.ReferenceNotes ‑gtk‑key‑bindings none | 〈binding name〉 [ , 〈binding name〉 ]* none 〈binding name〉 must have been assigned to a binding set with a @binding-set rule.