{
    "atrules": {
        "charset": {
            "prelude": "<string>"
        },
        "container": {
            "prelude": "[ <container-name> ]? <container-condition>"
        },
        "font-face": {
            "descriptors": {
                "unicode-range": {
                    "comment": "replaces <unicode-range>, an old production name",
                    "syntax": "<urange>#"
                }
            }
        },
        "font-features-values": {
            "comment": "The features values syntax is defined in https://www.w3.org/TR/css-fonts-4/#at-ruledef-font-feature-values",
            "prelude": "[<string> | <custom-ident>]+",
            "descriptors": {
                "font-display": "auto | block | swap | fallback | optional"
            }
        },
        "scope": {
            "prelude": "[ ( <scope-start> ) ]? [ to ( <scope-end> ) ]?"
        },
        "position-try": {
            "comment": "The list of descriptors: https://developer.mozilla.org/en-US/docs/Web/CSS/@position-try",
            "descriptors": {
                "top": "<'top'>",
                "left": "<'left'>",
                "bottom": "<'bottom'>",
                "right": "<'right'>",
                "inset-block-start": "<'inset-block-start'>",
                "inset-block-end": "<'inset-block-end'>",
                "inset-inline-start": "<'inset-inline-start'>",
                "inset-inline-end": "<'inset-inline-end'>",
                "inset-block": "<'inset-block'>",
                "inset-inline": "<'inset-inline'>",
                "inset": "<'inset'>",
                "margin-top": "<'margin-top'>",
                "margin-left": "<'margin-left'>",
                "margin-bottom": "<'margin-bottom'>",
                "margin-right": "<'margin-right'>",
                "margin-block-start": "<'margin-block-start'>",
                "margin-block-end": "<'margin-block-end'>",
                "margin-inline-start": "<'margin-inline-start'>",
                "margin-inline-end": "<'margin-inline-end'>",
                "margin": "<'margin'>",
                "margin-block": "<'margin-block'>",
                "margin-inline": "<'margin-inline'>",
                "width": "<'width'>",
                "height": "<'height'>",
                "min-width": "<'min-width'>",
                "min-height": "<'min-height'>",
                "max-width": "<'max-width'>",
                "max-height": "<'max-height'>",
                "block-size": "<'block-size'>",
                "inline-size": "<'inline-size'>",
                "min-block-size": "<'min-block-size'>",
                "min-inline-size": "<'min-inline-size'>",
                "max-block-size": "<'max-block-size'>",
                "max-inline-size": "<'max-inline-size'>",
                "align-self": "<'align-self'> | anchor-center",
                "justify-self": "<'justify-self'> | anchor-center"
            }
        }
    },
    "properties": {
        "-moz-background-clip": {
            "comment": "deprecated syntax in old Firefox, https://developer.mozilla.org/en/docs/Web/CSS/background-clip",
            "syntax": "padding | border"
        },
        "-moz-border-radius-bottomleft": {
            "comment": "https://developer.mozilla.org/en-US/docs/Web/CSS/border-bottom-left-radius",
            "syntax": "<'border-bottom-left-radius'>"
        },
        "-moz-border-radius-bottomright": {
            "comment": "https://developer.mozilla.org/en-US/docs/Web/CSS/border-bottom-right-radius",
            "syntax": "<'border-bottom-right-radius'>"
        },
        "-moz-border-radius-topleft": {
            "comment": "https://developer.mozilla.org/en-US/docs/Web/CSS/border-top-left-radius",
            "syntax": "<'border-top-left-radius'>"
        },
        "-moz-border-radius-topright": {
            "comment": "https://developer.mozilla.org/en-US/docs/Web/CSS/border-bottom-right-radius",
            "syntax": "<'border-bottom-right-radius'>"
        },
        "-moz-control-character-visibility": {
            "comment": "firefox specific keywords, https://bugzilla.mozilla.org/show_bug.cgi?id=947588",
            "syntax": "visible | hidden"
        },
        "-moz-osx-font-smoothing": {
            "comment": "misssed old syntax https://developer.mozilla.org/en-US/docs/Web/CSS/font-smooth",
            "syntax": "auto | grayscale"
        },
        "-moz-user-select": {
            "comment": "https://developer.mozilla.org/en-US/docs/Web/CSS/user-select",
            "syntax": "none | text | all | -moz-none"
        },
        "-ms-flex-align": {
            "comment": "misssed old syntax implemented in IE, https://www.w3.org/TR/2012/WD-css3-flexbox-20120322/#flex-align",
            "syntax": "start | end | center | baseline | stretch"
        },
        "-ms-flex-item-align": {
            "comment": "misssed old syntax implemented in IE, https://www.w3.org/TR/2012/WD-css3-flexbox-20120322/#flex-align",
            "syntax": "auto | start | end | center | baseline | stretch"
        },
        "-ms-flex-line-pack": {
            "comment": "misssed old syntax implemented in IE, https://www.w3.org/TR/2012/WD-css3-flexbox-20120322/#flex-line-pack",
            "syntax": "start | end | center | justify | distribute | stretch"
        },
        "-ms-flex-negative": {
            "comment": "misssed old syntax implemented in IE; TODO: find references for comfirmation",
            "syntax": "<'flex-shrink'>"
        },
        "-ms-flex-pack": {
            "comment": "misssed old syntax implemented in IE, https://www.w3.org/TR/2012/WD-css3-flexbox-20120322/#flex-pack",
            "syntax": "start | end | center | justify | distribute"
        },
        "-ms-flex-order": {
            "comment": "misssed old syntax implemented in IE; https://msdn.microsoft.com/en-us/library/jj127303(v=vs.85).aspx",
            "syntax": "<integer>"
        },
        "-ms-flex-positive": {
            "comment": "misssed old syntax implemented in IE; TODO: find references for comfirmation",
            "syntax": "<'flex-grow'>"
        },
        "-ms-flex-preferred-size": {
            "comment": "misssed old syntax implemented in IE; TODO: find references for comfirmation",
            "syntax": "<'flex-basis'>"
        },
        "-ms-interpolation-mode": {
            "comment": "https://msdn.microsoft.com/en-us/library/ff521095(v=vs.85).aspx",
            "syntax": "nearest-neighbor | bicubic"
        },
        "-ms-grid-column-align": {
            "comment": "add this property first since it uses as fallback for flexbox, https://msdn.microsoft.com/en-us/library/windows/apps/hh466338.aspx",
            "syntax": "start | end | center | stretch"
        },
        "-ms-grid-row-align": {
            "comment": "add this property first since it uses as fallback for flexbox, https://msdn.microsoft.com/en-us/library/windows/apps/hh466348.aspx",
            "syntax": "start | end | center | stretch"
        },
        "-ms-hyphenate-limit-last": {
            "comment": "misssed old syntax implemented in IE; https://www.w3.org/TR/css-text-4/#hyphenate-line-limits",
            "syntax": "none | always | column | page | spread"
        },
        "-webkit-appearance": {
            "comment": "webkit specific keywords",
            "references": [
                "http://css-infos.net/property/-webkit-appearance"
            ],
            "syntax": "none | button | button-bevel | caps-lock-indicator | caret | checkbox | default-button | inner-spin-button | listbox | listitem | media-controls-background | media-controls-fullscreen-background | media-current-time-display | media-enter-fullscreen-button | media-exit-fullscreen-button | media-fullscreen-button | media-mute-button | media-overlay-play-button | media-play-button | media-seek-back-button | media-seek-forward-button | media-slider | media-sliderthumb | media-time-remaining-display | media-toggle-closed-captions-button | media-volume-slider | media-volume-slider-container | media-volume-sliderthumb | menulist | menulist-button | menulist-text | menulist-textfield | meter | progress-bar | progress-bar-value | push-button | radio | scrollbarbutton-down | scrollbarbutton-left | scrollbarbutton-right | scrollbarbutton-up | scrollbargripper-horizontal | scrollbargripper-vertical | scrollbarthumb-horizontal | scrollbarthumb-vertical | scrollbartrack-horizontal | scrollbartrack-vertical | searchfield | searchfield-cancel-button | searchfield-decoration | searchfield-results-button | searchfield-results-decoration | slider-horizontal | slider-vertical | sliderthumb-horizontal | sliderthumb-vertical | square-button | textarea | textfield | -apple-pay-button"
        },
        "-webkit-background-clip": {
            "comment": "https://developer.mozilla.org/en/docs/Web/CSS/background-clip",
            "syntax": "[ <visual-box> | border | padding | content | text ]#"
        },
        "-webkit-column-break-after": {
            "comment": "added, http://help.dottoro.com/lcrthhhv.php",
            "syntax": "always | auto | avoid"
        },
        "-webkit-column-break-before": {
            "comment": "added, http://help.dottoro.com/lcxquvkf.php",
            "syntax": "always | auto | avoid"
        },
        "-webkit-column-break-inside": {
            "comment": "added, http://help.dottoro.com/lclhnthl.php",
            "syntax": "always | auto | avoid"
        },
        "-webkit-font-smoothing": {
            "comment": "https://developer.mozilla.org/en-US/docs/Web/CSS/font-smooth",
            "syntax": "auto | none | antialiased | subpixel-antialiased"
        },
        "-webkit-mask-box-image": {
            "comment": "missed; https://developer.mozilla.org/en-US/docs/Web/CSS/-webkit-mask-box-image",
            "syntax": "[ <url> | <gradient> | none ] [ <length-percentage>{4} <-webkit-mask-box-repeat>{2} ]?"
        },
        "-webkit-print-color-adjust": {
            "comment": "missed",
            "references": [
                "https://developer.mozilla.org/en/docs/Web/CSS/-webkit-print-color-adjust"
            ],
            "syntax": "economy | exact"
        },
        "-webkit-text-security": {
            "comment": "missed; http://help.dottoro.com/lcbkewgt.php",
            "syntax": "none | circle | disc | square"
        },
        "-webkit-user-drag": {
            "comment": "missed; http://help.dottoro.com/lcbixvwm.php",
            "syntax": "none | element | auto"
        },
        "-webkit-user-select": {
            "comment": "auto is supported by old webkit, https://developer.mozilla.org/en-US/docs/Web/CSS/user-select",
            "syntax": "auto | none | text | all"
        },
        "alignment-baseline": {
            "comment": "added SVG property",
            "references": [
                "https://www.w3.org/TR/SVG/text.html#AlignmentBaselineProperty"
            ],
            "syntax": "auto | baseline | before-edge | text-before-edge | middle | central | after-edge | text-after-edge | ideographic | alphabetic | hanging | mathematical"
        },
        "baseline-shift": {
            "comment": "added SVG property",
            "references": [
                "https://www.w3.org/TR/SVG/text.html#BaselineShiftProperty"
            ],
            "syntax": "baseline | sub | super | <svg-length>"
        },
        "behavior": {
            "comment": "added old IE property https://msdn.microsoft.com/en-us/library/ms530723(v=vs.85).aspx",
            "syntax": "<url>+"
        },
        "container-type": {
            "comment": "https://www.w3.org/TR/css-contain-3/#propdef-container-type",
            "syntax": "normal || [ size | inline-size ]"
        },
        "cue": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "<'cue-before'> <'cue-after'>?"
        },
        "cue-after": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "<url> <decibel>? | none"
        },
        "cue-before": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "<url> <decibel>? | none"
        },
        "cursor": {
            "comment": "added legacy keywords: hand, -webkit-grab. -webkit-grabbing, -webkit-zoom-in, -webkit-zoom-out, -moz-grab, -moz-grabbing, -moz-zoom-in, -moz-zoom-out",
            "references": [
                "https://www.sitepoint.com/css3-cursor-styles/"
            ],
            "syntax": "[ [ <url> [ <x> <y> ]? , ]* [ auto | default | none | context-menu | help | pointer | progress | wait | cell | crosshair | text | vertical-text | alias | copy | move | no-drop | not-allowed | e-resize | n-resize | ne-resize | nw-resize | s-resize | se-resize | sw-resize | w-resize | ew-resize | ns-resize | nesw-resize | nwse-resize | col-resize | row-resize | all-scroll | zoom-in | zoom-out | grab | grabbing | hand | -webkit-grab | -webkit-grabbing | -webkit-zoom-in | -webkit-zoom-out | -moz-grab | -moz-grabbing | -moz-zoom-in | -moz-zoom-out ] ]"
        },
        "display": {
            "comment": "extended with -ms-flexbox",
            "syntax": "| <-non-standard-display>"
        },
        "position": {
            "comment": "extended with -webkit-sticky",
            "syntax": "| -webkit-sticky"
        },
        "dominant-baseline": {
            "comment": "added SVG property",
            "references": [
                "https://www.w3.org/TR/SVG/text.html#DominantBaselineProperty"
            ],
            "syntax": "auto | use-script | no-change | reset-size | ideographic | alphabetic | hanging | mathematical | central | middle | text-after-edge | text-before-edge"
        },
        "image-rendering": {
            "comment": "extended with <-non-standard-image-rendering>, added SVG keywords optimizeSpeed and optimizeQuality",
            "references": [
                "https://developer.mozilla.org/en/docs/Web/CSS/image-rendering",
                "https://www.w3.org/TR/SVG/painting.html#ImageRenderingProperty"
            ],
            "syntax": "| optimizeSpeed | optimizeQuality | <-non-standard-image-rendering>"
        },
        "fill-opacity": {
            "comment": "added SVG property",
            "references": [
                "https://developer.mozilla.org/en-US/docs/Web/CSS/fill-opacity",
                "https://www.w3.org/TR/SVG/painting.html#FillProperty"
            ],
            "syntax": "<number-zero-one> | <percentage>"
        },
        "filter": {
            "comment": "extend with IE legacy syntaxes",
            "syntax": "| <-ms-filter-function-list>"
        },
        "font": {
            "comment": "align with font-4, fix <'font-family'>#, add non standard fonts",
            "references": [
                "https://drafts.csswg.org/css-fonts-4/#font-prop",
                "https://github.com/w3c/csswg-drafts/pull/10832",
                "https://webkit.org/blog/3709/using-the-system-font-in-web-content/"
            ],
            "syntax": "[ [ <'font-style'> || <font-variant-css2> || <'font-weight'> || <font-width-css3> ]? <'font-size'> [ / <'line-height'> ]? <'font-family'># ] | <system-family-name> | <-non-standard-font>"
        },
        "glyph-orientation-horizontal": {
            "comment": "added SVG property",
            "references": [
                "https://www.w3.org/TR/SVG/text.html#GlyphOrientationHorizontalProperty"
            ],
            "syntax": "<angle>"
        },
        "glyph-orientation-vertical": {
            "comment": "added SVG property",
            "references": [
                "https://www.w3.org/TR/SVG/text.html#GlyphOrientationVerticalProperty"
            ],
            "syntax": "<angle>"
        },
        "kerning": {
            "comment": "added SVG property",
            "references": [
                "https://www.w3.org/TR/SVG/text.html#KerningProperty"
            ],
            "syntax": "auto | <svg-length>"
        },
        "letter-spacing": {
            "comment": "fix syntax <length> -> <length-percentage>",
            "references": [
                "https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/letter-spacing"
            ],
            "syntax": "normal | <length-percentage>"
        },
        "max-width": {
            "comment": "extend by non-standard size keywords https://developer.mozilla.org/en-US/docs/Web/CSS/width",
            "syntax": "| stretch | <-non-standard-size>"
        },
        "max-height": {
            "comment": "extend by non-standard size keywords https://developer.mozilla.org/en-US/docs/Web/CSS/width",
            "syntax": "| stretch | <-non-standard-size>"
        },
        "width": {
            "references": [
                "https://developer.mozilla.org/en-US/docs/Web/CSS/width",
                "https://github.com/csstree/stylelint-validator/issues/29"
            ],
            "syntax": "| stretch | <-non-standard-size>"
        },
        "height": {
            "syntax": "| stretch | <-non-standard-size>"
        },
        "min-width": {
            "comment": "extend by non-standard width keywords https://developer.mozilla.org/en-US/docs/Web/CSS/width",
            "syntax": "| stretch | <-non-standard-size>"
        },
        "min-height": {
            "syntax": "| stretch | <-non-standard-size>"
        },
        "overflow": {
            "comment": "extend by vendor keywords https://developer.mozilla.org/en-US/docs/Web/CSS/overflow",
            "syntax": "| <-non-standard-overflow>"
        },
        "overflow-x": {
            "comment": "extend by vendor keywords https://developer.mozilla.org/en-US/docs/Web/CSS/overflow-x",
            "syntax": "| <-non-standard-overflow>"
        },
        "overflow-y": {
            "comment": "extend by vendor keywords https://developer.mozilla.org/en-US/docs/Web/CSS/overflow-y",
            "syntax": "| <-non-standard-overflow>"
        },
        "overflow-block": {
            "comment": "extend by vendor keywords https://developer.mozilla.org/en-US/docs/Web/CSS/overflow-y",
            "syntax": "| <-non-standard-overflow>"
        },
        "overflow-inline": {
            "comment": "extend by vendor keywords https://developer.mozilla.org/en-US/docs/Web/CSS/overflow-x",
            "syntax": "| <-non-standard-overflow>"
        },
        "pause": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "<'pause-before'> <'pause-after'>?"
        },
        "pause-after": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "<time> | none | x-weak | weak | medium | strong | x-strong"
        },
        "pause-before": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "<time> | none | x-weak | weak | medium | strong | x-strong"
        },
        "position-try-options": {
            "comment": "https://developer.mozilla.org/en-US/docs/Web/CSS/position-try-fallbacks",
            "syntax": "<'position-try-fallbacks'>"
        },
        "rest": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "<'rest-before'> <'rest-after'>?"
        },
        "rest-after": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "<time> | none | x-weak | weak | medium | strong | x-strong"
        },
        "rest-before": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "<time> | none | x-weak | weak | medium | strong | x-strong"
        },
        "speak": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "auto | never | always"
        },
        "stroke-dasharray": {
            "comment": "added SVG property; a list of comma and/or white space separated <length>s and <percentage>s",
            "references": [
                "https://www.w3.org/TR/SVG/painting.html#StrokeProperties"
            ],
            "syntax": "none | [ <svg-length>+ ]#"
        },
        "stroke-dashoffset": {
            "comment": "added SVG property",
            "references": [
                "https://www.w3.org/TR/SVG/painting.html#StrokeProperties"
            ],
            "syntax": "<svg-length>"
        },
        "stroke-linejoin": {
            "comment": "added SVG property",
            "references": [
                "https://www.w3.org/TR/SVG/painting.html#StrokeProperties"
            ],
            "syntax": "miter | round | bevel"
        },
        "stroke-miterlimit": {
            "comment": "added SVG property (<miterlimit> = <number-one-or-greater>) ",
            "references": [
                "https://www.w3.org/TR/SVG/painting.html#StrokeProperties"
            ],
            "syntax": "<number-one-or-greater>"
        },
        "stroke-width": {
            "comment": "added SVG property",
            "references": [
                "https://www.w3.org/TR/SVG/painting.html#StrokeProperties"
            ],
            "syntax": "<svg-length>"
        },
        "unicode-bidi": {
            "comment": "added prefixed keywords https://developer.mozilla.org/en-US/docs/Web/CSS/unicode-bidi",
            "syntax": "| -moz-isolate | -moz-isolate-override | -moz-plaintext | -webkit-isolate | -webkit-isolate-override | -webkit-plaintext"
        },
        "voice-balance": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "<number> | left | center | right | leftwards | rightwards"
        },
        "voice-duration": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "auto | <time>"
        },
        "voice-family": {
            "comment": "<name> -> <family-name>, https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "[ [ <family-name> | <generic-voice> ] , ]* [ <family-name> | <generic-voice> ] | preserve"
        },
        "voice-pitch": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "<frequency> && absolute | [ [ x-low | low | medium | high | x-high ] || [ <frequency> | <semitones> | <percentage> ] ]"
        },
        "voice-range": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "<frequency> && absolute | [ [ x-low | low | medium | high | x-high ] || [ <frequency> | <semitones> | <percentage> ] ]"
        },
        "voice-rate": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "[ normal | x-slow | slow | medium | fast | x-fast ] || <percentage>"
        },
        "voice-stress": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "normal | strong | moderate | none | reduced"
        },
        "voice-volume": {
            "comment": "https://www.w3.org/TR/css3-speech/#property-index",
            "syntax": "silent | [ [ x-soft | soft | medium | loud | x-loud ] || <decibel> ]"
        },
        "writing-mode": {
            "comment": "extend with SVG keywords",
            "syntax": "| <svg-writing-mode>"
        },
        "white-space-trim": {
            "syntax": "none | discard-before || discard-after || discard-inner",
            "comment": "missed, https://www.w3.org/TR/css-text-4/#white-space-trim"
        }
    },
    "types": {
        "-legacy-gradient": {
            "comment": "added collection of legacy gradient syntaxes",
            "syntax": "<-webkit-gradient()> | <-legacy-linear-gradient> | <-legacy-repeating-linear-gradient> | <-legacy-radial-gradient> | <-legacy-repeating-radial-gradient>"
        },
        "-legacy-linear-gradient": {
            "comment": "like standard syntax but w/o `to` keyword https://developer.mozilla.org/en-US/docs/Web/CSS/linear-gradient",
            "syntax": "-moz-linear-gradient( <-legacy-linear-gradient-arguments> ) | -webkit-linear-gradient( <-legacy-linear-gradient-arguments> ) | -o-linear-gradient( <-legacy-linear-gradient-arguments> )"
        },
        "-legacy-repeating-linear-gradient": {
            "comment": "like standard syntax but w/o `to` keyword https://developer.mozilla.org/en-US/docs/Web/CSS/linear-gradient",
            "syntax": "-moz-repeating-linear-gradient( <-legacy-linear-gradient-arguments> ) | -webkit-repeating-linear-gradient( <-legacy-linear-gradient-arguments> ) | -o-repeating-linear-gradient( <-legacy-linear-gradient-arguments> )"
        },
        "-legacy-linear-gradient-arguments": {
            "comment": "like standard syntax but w/o `to` keyword https://developer.mozilla.org/en-US/docs/Web/CSS/linear-gradient",
            "syntax": "[ <angle> | <side-or-corner> ]? , <color-stop-list>"
        },
        "-legacy-radial-gradient": {
            "comment": "deprecated syntax that implemented by some browsers https://www.w3.org/TR/2011/WD-css3-images-20110908/#radial-gradients",
            "syntax": "-moz-radial-gradient( <-legacy-radial-gradient-arguments> ) | -webkit-radial-gradient( <-legacy-radial-gradient-arguments> ) | -o-radial-gradient( <-legacy-radial-gradient-arguments> )"
        },
        "-legacy-repeating-radial-gradient": {
            "comment": "deprecated syntax that implemented by some browsers https://www.w3.org/TR/2011/WD-css3-images-20110908/#radial-gradients",
            "syntax": "-moz-repeating-radial-gradient( <-legacy-radial-gradient-arguments> ) | -webkit-repeating-radial-gradient( <-legacy-radial-gradient-arguments> ) | -o-repeating-radial-gradient( <-legacy-radial-gradient-arguments> )"
        },
        "-legacy-radial-gradient-arguments": {
            "comment": "deprecated syntax that implemented by some browsers https://www.w3.org/TR/2011/WD-css3-images-20110908/#radial-gradients",
            "syntax": "[ <position> , ]? [ [ [ <-legacy-radial-gradient-shape> || <-legacy-radial-gradient-size> ] | [ <length> | <percentage> ]{2} ] , ]? <color-stop-list>"
        },
        "-legacy-radial-gradient-size": {
            "comment": "before a standard it contains 2 extra keywords (`contain` and `cover`) https://www.w3.org/TR/2011/WD-css3-images-20110908/#ltsize",
            "syntax": "closest-side | closest-corner | farthest-side | farthest-corner | contain | cover"
        },
        "-legacy-radial-gradient-shape": {
            "comment": "define to double sure it doesn't extends in future https://www.w3.org/TR/2011/WD-css3-images-20110908/#ltshape",
            "syntax": "circle | ellipse"
        },
        "-non-standard-font": {
            "comment": "non standard fonts",
            "references": [
                "https://webkit.org/blog/3709/using-the-system-font-in-web-content/"
            ],
            "syntax": "-apple-system-body | -apple-system-headline | -apple-system-subheadline | -apple-system-caption1 | -apple-system-caption2 | -apple-system-footnote | -apple-system-short-body | -apple-system-short-headline | -apple-system-short-subheadline | -apple-system-short-caption1 | -apple-system-short-footnote | -apple-system-tall-body"
        },
        "-non-standard-color": {
            "comment": "non standard colors",
            "references": [
                "http://cssdot.ru/%D0%A1%D0%BF%D1%80%D0%B0%D0%B2%D0%BE%D1%87%D0%BD%D0%B8%D0%BA_CSS/color-i305.html",
                "https://developer.mozilla.org/en-US/docs/Web/CSS/color_value#Mozilla_Color_Preference_Extensions"
            ],
            "syntax": "-moz-ButtonDefault | -moz-ButtonHoverFace | -moz-ButtonHoverText | -moz-CellHighlight | -moz-CellHighlightText | -moz-Combobox | -moz-ComboboxText | -moz-Dialog | -moz-DialogText | -moz-dragtargetzone | -moz-EvenTreeRow | -moz-Field | -moz-FieldText | -moz-html-CellHighlight | -moz-html-CellHighlightText | -moz-mac-accentdarkestshadow | -moz-mac-accentdarkshadow | -moz-mac-accentface | -moz-mac-accentlightesthighlight | -moz-mac-accentlightshadow | -moz-mac-accentregularhighlight | -moz-mac-accentregularshadow | -moz-mac-chrome-active | -moz-mac-chrome-inactive | -moz-mac-focusring | -moz-mac-menuselect | -moz-mac-menushadow | -moz-mac-menutextselect | -moz-MenuHover | -moz-MenuHoverText | -moz-MenuBarText | -moz-MenuBarHoverText | -moz-nativehyperlinktext | -moz-OddTreeRow | -moz-win-communicationstext | -moz-win-mediatext | -moz-activehyperlinktext | -moz-default-background-color | -moz-default-color | -moz-hyperlinktext | -moz-visitedhyperlinktext | -webkit-activelink | -webkit-focus-ring-color | -webkit-link | -webkit-text"
        },
        "-non-standard-image-rendering": {
            "comment": "non-standard keywords http://phrogz.net/tmp/canvas_image_zoom.html",
            "syntax": "optimize-contrast | -moz-crisp-edges | -o-crisp-edges | -webkit-optimize-contrast"
        },
        "-non-standard-overflow": {
            "comment": "non-standard keywords https://developer.mozilla.org/en-US/docs/Web/CSS/overflow",
            "syntax": "overlay | -moz-scrollbars-none | -moz-scrollbars-horizontal | -moz-scrollbars-vertical | -moz-hidden-unscrollable"
        },
        "-non-standard-size": {
            "comment": "non-standard keywords https://developer.mozilla.org/en-US/docs/Web/CSS/width",
            "syntax": "intrinsic | min-intrinsic | -webkit-fill-available | -webkit-fit-content | -webkit-min-content | -webkit-max-content  | -moz-available | -moz-fit-content | -moz-min-content | -moz-max-content"
        },
        "-webkit-gradient()": {
            "comment": "first Apple proposal gradient syntax https://webkit.org/blog/175/introducing-css-gradients/ - TODO: simplify when after match algorithm improvement ( [, point, radius | , point] -> [, radius]? , point )",
            "syntax": "-webkit-gradient( <-webkit-gradient-type>, <-webkit-gradient-point> [, <-webkit-gradient-point> | , <-webkit-gradient-radius>, <-webkit-gradient-point> ] [, <-webkit-gradient-radius>]? [, <-webkit-gradient-color-stop>]* )"
        },
        "-webkit-gradient-color-stop": {
            "comment": "first Apple proposal gradient syntax https://webkit.org/blog/175/introducing-css-gradients/",
            "syntax": "from( <color> ) | color-stop( [ <number-zero-one> | <percentage> ] , <color> ) | to( <color> )"
        },
        "-webkit-gradient-point": {
            "comment": "first Apple proposal gradient syntax https://webkit.org/blog/175/introducing-css-gradients/",
            "syntax": "[ left | center | right | <length-percentage> ] [ top | center | bottom | <length-percentage> ]"
        },
        "-webkit-gradient-radius": {
            "comment": "first Apple proposal gradient syntax https://webkit.org/blog/175/introducing-css-gradients/",
            "syntax": "<length> | <percentage>"
        },
        "-webkit-gradient-type": {
            "comment": "first Apple proposal gradient syntax https://webkit.org/blog/175/introducing-css-gradients/",
            "syntax": "linear | radial"
        },
        "-webkit-mask-box-repeat": {
            "comment": "missed; https://developer.mozilla.org/en-US/docs/Web/CSS/-webkit-mask-box-image",
            "syntax": "repeat | stretch | round"
        },
        "-ms-filter-function-list": {
            "comment": "https://developer.mozilla.org/en-US/docs/Web/CSS/-ms-filter",
            "syntax": "<-ms-filter-function>+"
        },
        "-ms-filter-function": {
            "comment": "https://developer.mozilla.org/en-US/docs/Web/CSS/-ms-filter",
            "syntax": "<-ms-filter-function-progid> | <-ms-filter-function-legacy>"
        },
        "-ms-filter-function-progid": {
            "comment": "https://developer.mozilla.org/en-US/docs/Web/CSS/-ms-filter",
            "syntax": "'progid:' [ <ident-token> '.' ]* [ <ident-token> | <function-token> <any-value>? ) ]"
        },
        "-ms-filter-function-legacy": {
            "comment": "https://developer.mozilla.org/en-US/docs/Web/CSS/-ms-filter",
            "syntax": "<ident-token> | <function-token> <any-value>? )"
        },
        "age": {
            "comment": "https://www.w3.org/TR/css3-speech/#voice-family",
            "syntax": "child | young | old"
        },
        "attr-name": {
            "syntax": "<wq-name>"
        },
        "attr-fallback": {
            "syntax": "<any-value>"
        },
        "autospace": {
            "syntax": "no-autospace | [ ideograph-alpha || ideograph-numeric || punctuation ] || [ insert | replace ]"
        },
        "bottom": {
            "comment": "missed; not sure we should add it, but no others except `shape` is using it so it's ok for now; https://drafts.fxtf.org/css-masking-1/#funcdef-clip-rect",
            "syntax": "<length> | auto"
        },
        "content-list": {
            "comment": "added attr(), see https://github.com/csstree/csstree/issues/201",
            "syntax": "[ <string> | contents | <image> | <counter> | <quote> | <target> | <leader()> | <attr()> ]+"
        },
        "container-condition": {
            "comment": "missed, https://drafts.csswg.org/css-contain-3/#container-rule",
            "syntax": "not <query-in-parens> | <query-in-parens> [ [ and <query-in-parens> ]* | [ or <query-in-parens> ]* ]"
        },
        "coord-box": {
            "syntax": "content-box | padding-box | border-box | fill-box | stroke-box | view-box"
        },
        "cubic-bezier-easing-function": {
            "comment": "missed, https://drafts.csswg.org/css-easing-1/#cubic-bezier-easing-function",
            "syntax": "ease | ease-in | ease-out | ease-in-out | cubic-bezier( <number [0,1]> , <number> , <number [0,1]> , <number> )"
        },
        "element()": {
            "comment": "https://drafts.csswg.org/css-gcpm/#element-syntax & https://drafts.csswg.org/css-images-4/#element-notation",
            "syntax": "element( <custom-ident> , [ first | start | last | first-except ]? ) | element( <id-selector> )"
        },
        "generic-voice": {
            "comment": "https://www.w3.org/TR/css3-speech/#voice-family",
            "syntax": "[ <age>? <gender> <integer>? ]"
        },
        "gender": {
            "comment": "https://www.w3.org/TR/css3-speech/#voice-family",
            "syntax": "male | female | neutral"
        },
        "general-enclosed": {
            "comment": "remove ident-token, optional any-value, brackets (see https://drafts.csswg.org/mediaqueries-5/#typedef-general-enclosed)",
            "syntax": "[ <function-token> <any-value>? ) ] | [ ( <any-value>? ) ]"
        },
        "generic-family": {
            "comment": "new definition on font-4, https://drafts.csswg.org/css-fonts-4/#typedef-generic-family",
            "syntax": "<generic-script-specific>| <generic-complete> | <generic-incomplete> | <-non-standard-generic-family>"
        },
        "generic-script-specific": {
            "syntax": "generic(kai) | generic(fangsong) | generic(nastaliq)"
        },
        "-non-standard-generic-family": {
            "syntax": "-apple-system | BlinkMacSystemFont",
            "references": [
                "https://css-tricks.com/snippets/css/system-font-stack/",
                "https://webkit.org/blog/3709/using-the-system-font-in-web-content/"
            ]
        },
        "gradient": {
            "comment": "added legacy syntaxes support",
            "syntax": "| <-legacy-gradient>"
        },
        "intrinsic-size-keyword": {
            "comment": "Missing from mdn-data. 4.3. Intrinsic Size Keywords https://www.w3.org/TR/css-sizing-4/#intrinsic-size-keywords",
            "syntax": "min-content | max-content | fit-content"
        },
        "left": {
            "comment": "missed; not sure we should add it, but no others except `shape` is using it so it's ok for now; https://drafts.fxtf.org/css-masking-1/#funcdef-clip-rect",
            "syntax": "<length> | auto"
        },
        "color": {
            "comment": "css-color-5, added non standard color names",
            "syntax": "<color-base> | currentColor | <system-color> | <device-cmyk()>  | <light-dark()> | <-non-standard-color>"
        },
        "device-cmyk()": {
            "syntax": "<legacy-device-cmyk-syntax> | <modern-device-cmyk-syntax>"
        },
        "legacy-device-cmyk-syntax": {
            "syntax": "device-cmyk( <number>#{4} )"
        },
        "modern-device-cmyk-syntax": {
            "syntax": "device-cmyk( <cmyk-component>{4} [ / [ <alpha-value> | none ] ]? )"
        },
        "cmyk-component": {
            "syntax": "<number> | <percentage> | none"
        },
        "color-mix()": {
            "syntax": "color-mix( <color-interpolation-method> , [ <color> && <percentage [0,100]>? ]#{2} )"
        },
        "color-space": {
            "syntax": "<rectangular-color-space> | <polar-color-space> | <custom-color-space>"
        },
        "paint": {
            "comment": "used by SVG https://www.w3.org/TR/SVG/painting.html#SpecifyingPaint",
            "syntax": "none | <color> | <url> [ none | <color> ]? | context-fill | context-stroke"
        },
        "right": {
            "comment": "missed; not sure we should add it, but no others except `shape` is using it so it's ok for now; https://drafts.fxtf.org/css-masking-1/#funcdef-clip-rect",
            "syntax": "<length> | auto"
        },
        "shape": {
            "comment": "missed spaces in function body and add backwards compatible syntax",
            "syntax": "rect( <top>, <right>, <bottom>, <left> ) | rect( <top> <right> <bottom> <left> )"
        },
        "scope-start": {
            "syntax": "<forgiving-selector-list>"
        },
        "scope-end": {
            "syntax": "<forgiving-selector-list>"
        },
        "forgiving-selector-list": {
            "syntax": "<complex-real-selector-list>"
        },
        "forgiving-relative-selector-list": {
            "syntax": "<relative-real-selector-list>"
        },
        "complex-real-selector-list": {
            "syntax": "<complex-real-selector>#"
        },
        "simple-selector-list": {
            "syntax": "<simple-selector>#"
        },
        "relative-real-selector-list": {
            "syntax": "<relative-real-selector>#"
        },
        "complex-selector": {
            "syntax": "<complex-selector-unit> [ <combinator>? <complex-selector-unit> ]*"
        },
        "complex-selector-unit": {
            "syntax": "[ <compound-selector>? <pseudo-compound-selector>* ]!"
        },
        "complex-real-selector": {
            "syntax": "<compound-selector> [ <combinator>? <compound-selector> ]*"
        },
        "relative-real-selector": {
            "syntax": "<combinator>? <complex-real-selector>"
        },
        "compound-selector": {
            "syntax": "[ <type-selector>? <subclass-selector>* ]!"
        },
        "pseudo-compound-selector": {
            "syntax": " <pseudo-element-selector> <pseudo-class-selector>*"
        },
        "simple-selector": {
            "syntax": "<type-selector> | <subclass-selector>"
        },
        "combinator": {
            "syntax": "'>' | '+' | '~' | [ '|' '|' ]"
        },
        "pseudo-element-selector": {
            "syntax": "':' <pseudo-class-selector> | <legacy-pseudo-element-selector>"
        },
        "legacy-pseudo-element-selector": {
            "syntax": " ':' [before | after | first-line | first-letter]"
        },
        "svg-length": {
            "comment": "All coordinates and lengths in SVG can be specified with or without a unit identifier",
            "references": [
                "https://www.w3.org/TR/SVG11/coords.html#Units"
            ],
            "syntax": "<percentage> | <length> | <number>"
        },
        "svg-writing-mode": {
            "comment": "SVG specific keywords (deprecated for CSS)",
            "references": [
                "https://developer.mozilla.org/en/docs/Web/CSS/writing-mode",
                "https://www.w3.org/TR/SVG/text.html#WritingModeProperty"
            ],
            "syntax": "lr-tb | rl-tb | tb-rl | lr | rl | tb"
        },
        "top": {
            "comment": "missed; not sure we should add it, but no others except `shape` is using it so it's ok for now; https://drafts.fxtf.org/css-masking-1/#funcdef-clip-rect",
            "syntax": "<length> | auto"
        },
        "x": {
            "comment": "missed; not sure we should add it, but no others except `cursor` is using it so it's ok for now; https://drafts.csswg.org/css-ui-3/#cursor",
            "syntax": "<number>"
        },
        "y": {
            "comment": "missed; not sure we should add it, but no others except `cursor` is using so it's ok for now; https://drafts.csswg.org/css-ui-3/#cursor",
            "syntax": "<number>"
        },
        "declaration": {
            "comment": "missed, restored by https://drafts.csswg.org/css-syntax",
            "syntax": "<ident-token> : <declaration-value>? [ '!' important ]?"
        },
        "declaration-list": {
            "comment": "missed, restored by https://drafts.csswg.org/css-syntax",
            "syntax": "[ <declaration>? ';' ]* <declaration>?"
        },
        "url": {
            "comment": "https://drafts.csswg.org/css-values-4/#urls",
            "syntax": "url( <string> <url-modifier>* ) | <url-token>"
        },
        "url-modifier": {
            "comment": "https://drafts.csswg.org/css-values-4/#typedef-url-modifier",
            "syntax": "<ident> | <function-token> <any-value> )"
        },
        "number-zero-one": {
            "syntax": "<number [0,1]>"
        },
        "number-one-or-greater": {
            "syntax": "<number [1,∞]>"
        },
        "color()": {
            "syntax": "color( <colorspace-params> [ / [ <alpha-value> | none ] ]? )"
        },
        "colorspace-params": {
            "syntax": "[ <predefined-rgb-params> | <xyz-params>]"
        },
        "xyz-params": {
            "syntax": "<xyz-space> [ <number> | <percentage> | none ]{3}"
        },
        "xyz-space": {
            "syntax": "xyz | xyz-d50 | xyz-d65"
        },
        "query-in-parens": {
            "comment": "missed, https://drafts.csswg.org/css-contain-3/#container-rule",
            "syntax": "( <container-condition> ) | ( <size-feature> ) | style( <style-query> ) | <general-enclosed>"
        },
        "size-feature": {
            "comment": "missed, https://drafts.csswg.org/css-contain-3/#typedef-size-feature",
            "syntax": "<mf-plain> | <mf-boolean> | <mf-range>"
        },
        "style-query": {
            "comment": "missed, https://drafts.csswg.org/css-contain-3/#container-rule",
            "syntax": "<style-condition> | <style-feature>"
        },
        "style-condition": {
            "comment": "missed, https://drafts.csswg.org/css-contain-3/#container-rule",
            "syntax": "not <style-in-parens> | <style-in-parens> [ [ and <style-in-parens> ]* | [ or <style-in-parens> ]* ]"
        },
        "style-in-parens": {
            "comment": "missed, https://drafts.csswg.org/css-contain-3/#container-rule",
            "syntax": "( <style-condition> ) | ( <style-feature> ) | <general-enclosed>"
        },
        "-non-standard-display": {
            "syntax": "-ms-inline-flexbox | -ms-grid | -ms-inline-grid | -webkit-flex | -webkit-inline-flex | -webkit-box | -webkit-inline-box | -moz-inline-stack | -moz-box | -moz-inline-box"
        },
        "inset-area": {
            "syntax": "[ [ left | center | right | span-left | span-right | x-start | x-end | span-x-start | span-x-end | x-self-start | x-self-end | span-x-self-start | span-x-self-end | span-all ] || [ top | center | bottom | span-top | span-bottom | y-start | y-end | span-y-start | span-y-end | y-self-start | y-self-end | span-y-self-start | span-y-self-end | span-all ] | [ block-start | center | block-end | span-block-start | span-block-end | span-all ] || [ inline-start | center | inline-end | span-inline-start | span-inline-end | span-all ] | [ self-block-start | self-block-end | span-self-block-start | span-self-block-end | span-all ] || [ self-inline-start | self-inline-end | span-self-inline-start | span-self-inline-end | span-all ] | [ start | center | end | span-start | span-end | span-all ]{1,2} | [ self-start | center | self-end | span-self-start | span-self-end | span-all ]{1,2} ]",
            "comment": "initial name for <position-area> before renamed",
            "references": [
                "https://www.w3.org/TR/css-anchor-position-1/#inset-area"
            ]
        },
        "position-area": {
            "syntax": "[ [ left | center | right | span-left | span-right | x-start | x-end | span-x-start | span-x-end | x-self-start | x-self-end | span-x-self-start | span-x-self-end | span-all ] || [ top | center | bottom | span-top | span-bottom | y-start | y-end | span-y-start | span-y-end | y-self-start | y-self-end | span-y-self-start | span-y-self-end | span-all ] | [ block-start | center | block-end | span-block-start | span-block-end | span-all ] || [ inline-start | center | inline-end | span-inline-start | span-inline-end | span-all ] | [ self-block-start | center | self-block-end | span-self-block-start | span-self-block-end | span-all ] || [ self-inline-start | center | self-inline-end | span-self-inline-start | span-self-inline-end | span-all ] | [ start | center | end | span-start | span-end | span-all ]{1,2} | [ self-start | center | self-end | span-self-start | span-self-end | span-all ]{1,2} ]",
            "comment": "replaced <inset-area>",
            "references": [
                "https://drafts.csswg.org/css-anchor-position-1/#typedef-position-area"
            ]
        },
        "syntax": {
            "syntax": "'*' | <syntax-component> [ <syntax-combinator> <syntax-component> ]* | <syntax-string>"
        },
        "syntax-component": {
            "syntax": "<syntax-single-component> <syntax-multiplier>? | '<' transform-list '>'"
        },
        "syntax-single-component": {
            "syntax": "'<' <syntax-type-name> '>' | <ident>"
        },
        "syntax-type-name": {
            "syntax": "angle | color | custom-ident | image | integer | length | length-percentage | number | percentage | resolution | string | time | url | transform-function"
        },
        "syntax-combinator": {
            "syntax": "'|'"
        },
        "syntax-multiplier": {
            "syntax": "'#' | '+'"
        },
        "syntax-string": {
            "syntax": "<string>"
        }
    }
}