CSS properties

Implements an explicit fragmentainer height, including zero-height cases. Together with column-wrap, it determines column groups across multiple rows.

The border-style shorthand accepts color functions containing whitespace. It changes only supplied components and does not reset omitted components. List shorthand syntax is not fully implemented.

Controls breaks in rule lines at spanning items and intersections, and is used by painting.

Accepts color lists and repeat groups. currentColor resolves to the current text color when the style is applied.

Insets the corresponding edge or interior endpoint of a rule line. Percentages are retained until painting; calc is currently unsupported.

Insets the corresponding edge or interior endpoint of a rule line. Percentages are retained until painting; calc is currently unsupported.

Writes the same value to all four edge/interior start/end endpoints. This value parser does not accept calc.

Insets the corresponding edge or interior endpoint of a rule line. Percentages are retained until painting; calc is currently unsupported.

Insets the corresponding edge or interior endpoint of a rule line. Percentages are retained until painting; calc is currently unsupported.

The parser accepts more styles than some gap-painting paths can draw. Each decoration context has its own visible-style checks; accepting all border styles does not establish complete CSS Gap Decorations coverage.

normal maps to auto. Controls segment visibility according to adjacent or surrounding items.

Converts single values and lists to actual lengths. In lists and shorthands, thin/medium/thick resolve to 1/3/5px. Used by flex, grid, and multicolumn painting.

Spanning items divide text and block flow into segments. Both ordinary and nested spanner paths exist.

Derives the column count and width together with column-count. The longhand converts relative lengths.

wrap enables grouping columns into rows; auto enables it when column-height is present. The implementation remains a subset of multicolumn layout.

Includes the Level 2 height suffix. For a Dimension, the width component reads numericValue directly: units such as em/rem are not converted to px within this shorthand. Use the column-width longhand instead.

Angular color stops are not implemented: the shared parseGradientStopPosition explicitly rejects deg/rad/turn. Support for the from angle does not imply support for angle stops. The from angle supports deg/rad/grad/turn, with an at center and percentage/implicit stops. The backend uses a sweep shader; the mask backend has no conic branch. Supports single-position and double-position color stops, affine length/percentage/calc stops and color hints. Stop correction is deferred until the actual gradient length is known. Explicit interpolation spaces are limited to srgb/srgb-linear/xyz/hsl/lch; the last two support shorter/longer/increasing/decreasing hue. Spaces such as lab/oklab/oklch/display-p3 are not included. Color hints use a bounded approximation with nine additional color stops. The background, border and list-image paths use these features; the mask path does not inherit this full capability set.

layout/paint establish a containing block, BFC, and stacking context; paint clips, and size affects intrinsic sizing and automatic height. No counter-scope use of the style bit was found. inline-size also sets the Size bit because it contains the substring size; it is not independent inline-axis containment.

The built-in registry, logical mapping, declaration expansion, and apply dispatch currently provide no implementation path that uses this property. Its appearance in examples, storage in CSSOM, or support for the corresponding standard property does not prove this name takes effect.

With a slash, sets name/type. Without a slash, recognizes only size/inline-size as a type; it does not implement the specified standalone-name and reset behavior.

Compares the whole string as one exact name. Multiple whitespace-separated names are not split into a list.

Used for ancestor size queries, containing blocks, and stacking contexts. No layout use converting container type to size containment was found; this does not establish complete container containment.

Structured content is used by pseudo-elements, markers and replacement images. Only built-in counter styles are available; unknown names fall back to decimal. The stylesheet tokenizer decodes escapes first. An unsupported function leaves the entire declaration without content. Neither / alt-text nor the full <image> syntax is implemented.

The built-in registry, logical mapping, declaration expansion, and apply dispatch currently provide no implementation path that uses this property. Its appearance in examples, storage in CSSOM, or support for the corresponding standard property does not prove this name takes effect.

Only collapse is consumed: it reuses the modern automatic line budget and suppresses the ellipsis. Values such as auto/discard must not be presented as complete Overflow 4 support.

Recursively parses absolute colors and selects black or white by sRGB relative-luminance contrast. Transparent arguments are not composited over a specific background. The caller must resolve contextual colors first; this is not a complete general color-context model.

The generic value/length-math parser has no semantics for this function. Storing the text of an unknown function does not establish support.

The default increment is 1. Used together with HTML list-item and pseudo-element counter scopes.

The default value is 0. reversed can omit its initial value, which is derived from descendant counter uses. Integers can be parsed through calc.

The default value is 0. Assigns a value to the counter in the current scope.

Animation and transition shorthands evaluate easing. Numeric scanning only handles comma/space separators and decimal prefixes; full numeric expressions such as calc are not accepted. The transition-timing-function longhand has additional first-item/keyword restrictions.

Contextual resolution exists for color inheritance, backgrounds and several border/decoration paths. Calling Color::parse alone does not establish support. Substitution of currentColor inside nested functions depends on the specific property path.

Only the 27 keywords in the canonical table are implemented. none, vertical-text, cell, alias, copy, no-drop, zoom-*, and custom url cursors are not implemented; system mappings may fall back differently across platforms.

The transform parser supports all four angle units. Generic calc CSSUnit only includes deg/rad/turn, so grad must not be treated as supported in every mathematical context.

Color::parse has no branch for this function. Storing its text or tolerating an unknown function does not implement its color semantics.

Affects paragraph direction, logical alignment, and layout direction, including bidi, inline-start/end, and Flex/Grid/Table coordinates and alignment. It does not replace unicode-bidi.

none creates no visible box; contents promotes child boxes. Modern multi-keyword parsing covers only list-item combinations; ordinary combinations such as block flex and inline grid are not handled by this parser. The legacy -webkit-box compatibility path works with line-clamp.

Usable only in properties that accept the value type. The consuming property determines the percentage basis. Physical units use 96 CSS px/in.

Controls background and border visibility for empty cells in tables using separate borders.

The generic value/length-math parser has no semantics for this function. Storing the text of an unknown function does not establish support.

The element apply path uses font measurements where possible, and fallback ratios when no callback exists. Other property-specific parsers may still differ.

The generic value/length-math parser has no semantics for this function. Storing the text of an unknown function does not establish support.

Applies only to internal SVG CSS and is handled by the SVG backend. It is not a ComputedStyle property of ordinary HTML boxes. The backend determines inheritance, colors/units, paint servers, and selector details. See the SVG internal CSS handoff entry for limits on forwarding host grouping rules.

Implements a filter chain. url(SVG-filter) is not supported. Ordinary filter values read only the numeric prefix: relative lengths in blur, angle units other than deg and similar cases do not use complete CSS unit parsing. backdrop-filter has no effect on the root element.

A KUI-specific CSS image function with dedicated parsing and painting in background/background-image, border-image-source and content. The available filters match the filter property. It is not an SVG URL filter reference or a standard general-purpose CSS image function.

Tokenization splits on top-level whitespace and accepts basis first and calc expressions containing whitespace. An omitted basis defaults to 0%; KUI_DISABLE_FLEX_SHORTHAND_ZERO_PERCENT_BASIS=1 restores 0px. Intrinsic basis values in the shorthand share the content sentinel and do not distinguish min-content from max-content.

Lengths, percentages, and math trees containing percentages are stored separately. Intrinsic keywords in the longhand are folded into auto, so complete independent intrinsic-basis behavior cannot be claimed.

Sets the main axis and its direction. Includes paths for RTL, column-direction percentages, and intrinsic sizing.

Declaration expansion writes only the components actually present; omitted components are not consistently reset to their initial values. This does not provide complete shorthand semantics.

Accepts non-negative grow/shrink factors; negative values are ignored.

Accepts non-negative grow/shrink factors; negative values are ignored.

Handles single lines, multiple lines, and a reversed cross axis.

Creates floats and a BFC, with shrink-to-fit sizing and normal-flow wrapping around floats. inline-start and inline-end are not implemented in this dispatch path.

Expands into five longhands; accepts inherit/initial/unset/revert. Composite components such as font-variant/font-stretch and system-font keyword paths are absent. oblique is expanded, but the longhand does not implement it.

Passes the list to the backend. Available fonts depend on the system, platform, and @font-face resources; glyphs and metrics must not be assumed identical across platforms.

The current property registry and StyleCore/Extras have no implementation that uses this element property. Tokenizer acceptance of its name, inclusion in the @supports allowlist, or the existence of imported tests does not establish support.

The current property registry and StyleCore/Extras have no implementation that uses this element property. Tokenizer acceptance of its name, inclusion in the @supports allowlist, or the existence of imported tests does not establish support.

The current property registry and StyleCore/Extras have no implementation that uses this element property. Tokenizer acceptance of its name, inclusion in the @supports allowlist, or the existence of imported tests does not establish support.

Absolute-size keywords use a table with medium at 16px. smaller/larger are calculated as 5/6 and 6/5 of the parent size. Lengths must be nonnegative.

Implements only a numeric x-height ratio. Does not implement from-font or newer metric syntax such as ex-height/cap-height/ch-width. Adjusts the nominal font size separately for each fallback font.

The current property registry and StyleCore/Extras have no implementation that uses this element property. Tokenizer acceptance of its name, inclusion in the @supports allowlist, or the existence of imported tests does not establish support.

oblique exists as a tokenizer keyword, but the apply branch recognizes only italic and maps other keywords to normal. oblique <angle> is absent.

The current property registry and StyleCore/Extras have no implementation that uses this element property. Tokenizer acceptance of its name, inclusion in the @supports allowlist, or the existence of imported tests does not establish support.

The current property registry and StyleCore/Extras have no implementation that uses this element property. Tokenizer acceptance of its name, inclusion in the @supports allowlist, or the existence of imported tests does not establish support.

The current property registry and StyleCore/Extras have no implementation that uses this element property. Tokenizer acceptance of its name, inclusion in the @supports allowlist, or the existence of imported tests does not establish support.

The current property registry and StyleCore/Extras have no implementation that uses this element property. Tokenizer acceptance of its name, inclusion in the @supports allowlist, or the existence of imported tests does not establish support.

The current property registry and StyleCore/Extras have no implementation that uses this element property. Tokenizer acceptance of its name, inclusion in the @supports allowlist, or the existence of imported tests does not establish support.

The current property registry and StyleCore/Extras have no implementation that uses this element property. Tokenizer acceptance of its name, inclusion in the @supports allowlist, or the existence of imported tests does not establish support.

Relative weights use a fallback table based on the inherited value. Available weights depend on the selected font and backend. Numeric values are converted to integers.

Used by flex and grid; column-gap also serves multicolumn layout. Affine calc expressions retain px and percentage terms. Non-affine math functions still use a two-sample approximation. normal is zero in flex/grid and 1em for the multicolumn column gap.

Currently only splits the two sides of a slash into template rows and columns. The auto-flow shorthand branch and complete reset semantics for areas and implicit tracks are not implemented.

A bare name uses a named area; slash-separated components accept the line syntax of the longhands. Spec-compliant inference of omitted components and named spans are incomplete.

Implicit tracks cycle through the definition and share math-value parsing with explicit tracks.

Auto-placement handles sparse placement and dense backfilling.

Implicit tracks cycle through the definition and share math-value parsing with explicit tracks.

Accepts numbers, named lines, negative indices, and integer spans. Spans using named lines remain subject to the longhand limitations.

Accepts negative line indices, named lines with occurrence counts, and integer spans. The numeric span parser rejects span <custom-ident> and treats it as auto.

Used by flex and grid; column-gap also serves multicolumn layout. Affine calc expressions retain px and percentage terms. Non-affine math functions still use a two-sample approximation. normal is zero in flex/grid and 1em for the multicolumn column gap.

Accepts negative line indices, named lines with occurrence counts, and integer spans. The numeric span parser rejects span <custom-ident> and treats it as auto.

Used by flex and grid; column-gap also serves multicolumn layout. Affine calc expressions retain px and percentage terms. Non-affine math functions still use a two-sample approximation. normal is zero in flex/grid and 1em for the multicolumn column gap.

Accepts numbers, named lines, negative indices, and integer spans. Spans using named lines remain subject to the longhand limitations.

Accepts negative line indices, named lines with occurrence counts, and integer spans. The numeric span parser rejects span <custom-ident> and treats it as auto.

Used by flex and grid; column-gap also serves multicolumn layout. Affine calc expressions retain px and percentage terms. Non-affine math functions still use a two-sample approximation. normal is zero in flex/grid and 1em for the multicolumn column gap.

Accepts negative line indices, named lines with occurrence counts, and integer spans. The numeric span parser rejects span <custom-ident> and treats it as auto.

A dedicated tokenizer expands the value and validates rectangular named areas, equal column counts, and track syntax. Does not include subgrid shorthand syntax.

String rows declare named areas. Full rectangular-area and equal-column validation exists in the grid-template shorthand helper; the standalone longhand path only collects strings, so strict rejection of every invalid area cannot be claimed.

Handles tracks, named lines, and repeat; math expressions retain percentages until layout. subgrid recognizes only the exact bare keyword and passes parent tracks and gap differences. Named lines after subgrid and the full spec chain for child intrinsic track contributions to the parent are not covered. The declarative KUI_DISABLE_SUBGRID flag does not remove runtime code.

Handles tracks, named lines, and repeat; math expressions retain percentages until layout. subgrid recognizes only the exact bare keyword and passes parent tracks and gap differences. Named lines after subgrid and the full spec chain for child intrinsic track contributions to the parent are not covered. The declarative KUI_DISABLE_SUBGRID flag does not remove runtime code.

Uses punctuation code points and line geometry to determine hanging at the beginning and end of a line. force-end takes precedence.

Lengths, percentages, and math trees are stored separately. Percentage resolution depends on whether the containing block size is definite or indefinite. Intrinsic sizing uses IntrinsicSizer, with separate constraints for replaced elements, flex, grid, and tables. anchor-size() is not included.

Converts hue units deg/rad/grad/turn. The parser has nonstandard error tolerance, converts none to numeric 0, and does not preserve missing components for interpolation or provide general relative syntax.

Converts to sRGB. The current HWB hue branch takes the raw numeric value without rad/grad/turn conversion. Full none/relative syntax and strict separator syntax are not guaranteed.

none suppresses U+00AD; manual permits line breaks at soft hyphens. auto is stored, but no automatic dictionary or language-based hyphenation engine was found. Automatic hyphenation must not be claimed.

The generic value/length-math parser has no semantics for this function. Storing the text of an unknown function does not establish support.

The element apply path uses font measurements where possible, and fallback ratios when no callback exists. Other property-specific parsers may still differ.

crisp-edges and pixelated both use nearest-neighbor sampling; auto, smooth and high-quality all use linear sampling. The specification algorithms are not each implemented separately.

In background/background-image, candidates are parsed and collapsed into a single image. Selection uses a fixed 1dppx target and the nearest candidate; equal distances keep the first candidate. Supports x/dppx/dpi/dpcm. type only filters through a MIME allowlist and does not prove that a decoder is available. Nonpositive resolutions are discarded; calc resolutions are simplified to 1x. This is not general support in arbitrary image contexts. Parsing happens before the entire background value is split into layers, and a source is selected only if the whole value starts with image-set. It does not recursively expand image-set within arbitrary layers; trailing shorthand and multilayer text are also limited.

Usable only in properties that accept the value type. The consuming property determines the percentage basis. Physical units use 96 CSS px/in.

Supports CSS-wide keywords. Explicit inherit takes the parent computed value; revert rolls back the current origin; revert-layer rolls back the current layer, with inline declarations handled separately. CSS-wide keywords introduced through variable substitution may not cover all static layer semantics.

Supports CSS-wide keywords. Explicit inherit takes the parent computed value; revert rolls back the current origin; revert-layer rolls back the current layer, with inline declarations handled separately. CSS-wide keywords introduced through variable substitution may not cover all static layer semantics.

Only maps horizontal-tb plus direction: RTL swaps inline start/end, block remains top/bottom, and size remains width/height. A vertical writing-mode does not change this mapping.

The declaration layer expands the value to four sides and accepts math functions containing whitespace. The internal applyProperty shorthand path differs from declaration expansion; this description follows the CSS declaration entry point.

Only maps block/inline in horizontal-tb; the inline direction follows direction. Ordinary inset/margin/padding pair shorthands split one or two values at top-level whitespace.

Only maps horizontal-tb plus direction: RTL swaps inline start/end, block remains top/bottom, and size remains width/height. A vertical writing-mode does not change this mapping.

Only maps horizontal-tb plus direction: RTL swaps inline start/end, block remains top/bottom, and size remains width/height. A vertical writing-mode does not change this mapping.

Only maps block/inline in horizontal-tb; the inline direction follows direction. Ordinary inset/margin/padding pair shorthands split one or two values at top-level whitespace.

Only maps horizontal-tb plus direction: RTL swaps inline start/end, block remains top/bottom, and size remains width/height. A vertical writing-mode does not change this mapping.

Only maps horizontal-tb plus direction: RTL swaps inline start/end, block remains top/bottom, and size remains width/height. A vertical writing-mode does not change this mapping.

Participates in stacking contexts and isolated layers.

Distributes flex/grid content. unsafe combinations are not included in this property parser branch.

Primarily affects grid layout. self-start/self-end, safe/unsafe, and legacy combinations are not implemented in this parser.

Used by grid and the shared absolute-positioning branch. anchor-center is a local centering fallback and does not represent complete anchor positioning.

Converts D50 Lab to XYZ to sRGB. Fast returns at L values of 0/100 discard the authored alpha. Does not provide full missing-component or relative-color syntax.

Converts through D50 Lab; hue accepts angle units. Fast returns at L values of 0/100 discard alpha. C percentages do not use the standard proportional conversion.

Percentages are resolved during layout. Affine calc expressions retain px and percentage terms; non-affine expressions are converted to numbers during style resolution, so a complete container reference cannot be claimed for every function.

Retains the percentage component and recalculates it using each descendant font size. Length components resolve in the declaring element context.

Usable only in properties that accept the value type. The consuming property determines the percentage basis. Physical units use 96 CSS px/in.

Color::parse has no branch for this function. Storing its text or tolerating an unknown function does not implement its color semantics.

Used through punctuation prohibition tables and materialized anywhere break opportunities. Final rasterization for a language/font still depends on the backend.

Modern mode activates directly; auto derives the line budget from a definite height/max-height. Only the standard automatic ellipsis marker, no marker and an empty string are implemented; nonempty custom block-ellipsis strings are not.

normal uses font metrics. A number retains its multiplier and is recalculated with the child font size; lengths and percentages are computed to absolute values.

The linear keyword is available; piecewise linear() has no parsing or interpolation model.

Supports deg/rad/grad/turn angles and corner directions; the default points downward. Supports single-position and double-position color stops, affine length/percentage/calc stops and color hints. Stop correction is deferred until the actual gradient length is known. Explicit interpolation spaces are limited to srgb/srgb-linear/xyz/hsl/lch; the last two support shorter/longer/increasing/decreasing hue. Spaces such as lab/oklab/oklch/display-p3 are not included. Color hints use a bounded approximation with nine additional color stops. The background, border and list-image paths use these features; the mask path does not inherit this full capability set.

The current branch scans only type and position. It neither parses nor resets image; use list-style-image separately.

URLs depend on successful resource loading; gradients use the shared parser. The full <image> syntax, including image-set and cross-fade, is not supported by this property.

Used by both marker painting and inline layout.

There are 55 built-in names and aliases (see the parser), including Georgian, Armenian, Greek, language-specific digits, kana and Chinese/Japanese/Korean forms. Arbitrary <string>, symbols() and custom @counter-style names are not supported.

The generic value/length-math parser has no semantics for this function. Storing the text of an unknown function does not establish support.

The declaration layer expands the value to four sides. Accepts auto, negative values, lengths, and percentages.

Only maps block/inline in horizontal-tb; the inline direction follows direction. Ordinary inset/margin/padding pair shorthands split one or two values at top-level whitespace.

Only maps horizontal-tb plus direction: RTL swaps inline start/end, block remains top/bottom, and size remains width/height. A vertical writing-mode does not change this mapping.

Only maps horizontal-tb plus direction: RTL swaps inline start/end, block remains top/bottom, and size remains width/height. A vertical writing-mode does not change this mapping.

Accepts negative margins, auto, percentages, and affine math terms. Percentages are resolved against the containing block inline size during layout. Complex non-affine expressions still have limitations because they are converted to numbers during style resolution.

Only maps block/inline in horizontal-tb; the inline direction follows direction. Ordinary inset/margin/padding pair shorthands split one or two values at top-level whitespace.

Only maps horizontal-tb plus direction: RTL swaps inline start/end, block remains top/bottom, and size remains width/height. A vertical writing-mode does not change this mapping.

Only maps horizontal-tb plus direction: RTL swaps inline start/end, block remains top/bottom, and size remains width/height. A vertical writing-mode does not change this mapping.

Accepts negative margins, auto, percentages, and affine math terms. Percentages are resolved against the containing block inline size during layout. Complex non-affine expressions still have limitations because they are converted to numbers during style resolution.

Accepts negative margins, auto, percentages, and affine math terms. Percentages are resolved against the containing block inline size during layout. Complex non-affine expressions still have limitations because they are converted to numbers during style resolution.

Accepts negative margins, auto, percentages, and affine math terms. Percentages are resolved against the containing block inline size during layout. Complex non-affine expressions still have limitations because they are converted to numbers during style resolution.

Margin trimming is applied in block, flex, and grid layout. Grid boundary selection is currently limited to LTR and horizontal-tb.

The basic shorthand only extracts the image source; it does not expand the complete mask grammar.

Storage only: applyMask currently does not read size/position/repeat/origin/clip/composite, so these values cannot be claimed to produce an effect.

Storage only: applyMask currently does not read size/position/repeat/origin/clip/composite, so these values cannot be claimed to produce an effect.

The image path is available. Splitting at bare commas limits gradients and data URIs containing commas. The backend only handles linear/radial gradients; all images are scaled to the box.

Only the first layer mode is applied to the entire composited mask. match-source does not distinguish SVG sources.

Storage only: applyMask currently does not read size/position/repeat/origin/clip/composite, so these values cannot be claimed to produce an effect.

Storage only: applyMask currently does not read size/position/repeat/origin/clip/composite, so these values cannot be claimed to produce an effect.

Storage only: applyMask currently does not read size/position/repeat/origin/clip/composite, so these values cannot be claimed to produce an effect.

Storage only: applyMask currently does not read size/position/repeat/origin/clip/composite, so these values cannot be claimed to produce an effect.

Supports nested math, parentheses, arithmetic operator precedence and numeric type validation. Limited by each property's accepted types and the depth budget.