{
  "font-face": {
    "spec": "https://drafts.csswg.org/css-fonts-4/#at-font-face-rule",
    "descriptors": {
      "ascent-override": {
        "initial": "normal",
        "syntax": [
          "normal",
          "<percentage [0,∞]>"
        ]
      },
      "descent-override": {
        "initial": "normal",
        "syntax": [
          "normal",
          "<percentage [0,∞]>"
        ]
      },
      "font-display": {
        "initial": "auto",
        "syntax": [
          "auto",
          "block",
          "swap",
          "fallback",
          "optional"
        ]
      },
      "font-family": {
        "syntax": [
          "<family-name>"
        ]
      },
      "font-feature-settings": {
        "initial": "normal",
        "syntax": [
          "<'font-feature-settings'>"
        ]
      },
      "font-language-override": {
        "initial": "normal",
        "syntax": [
          "normal",
          "<string>"
        ]
      },
      "font-named-instance": {
        "initial": "auto",
        "syntax": [
          "auto",
          "<string>"
        ]
      },
      "font-stretch": {
        "legacy-alias-for": "font-width"
      },
      "font-style": {
        "initial": "auto",
        "FIXME": "Support angles for oblique",
        "syntax": [
          "auto",
          "<'font-style'>"
        ]
      },
      "font-variation-settings": {
        "initial": "normal",
        "syntax": [
          "<'font-variation-settings'>"
        ]
      },
      "font-weight": {
        "initial": "auto",
        "syntax": [
          "auto",
          "<font-weight-absolute>{1,2}"
        ]
      },
      "font-width": {
        "initial": "auto",
        "FIXME": "Support multiple font-width values",
        "syntax": [
          "auto",
          "<'font-width'>"
        ]
      },
      "line-gap-override": {
        "initial": "normal",
        "syntax": [
          "normal",
          "<percentage [0,∞]>"
        ]
      },
      "src": {
        "syntax": [
          "<font-src-list>"
        ]
      },
      "unicode-range": {
        "initial": "U+0-10FFFF",
        "syntax": [
          "<unicode-range-token>#"
        ]
      }
    }
  },
  "page": {
    "spec": "https://drafts.csswg.org/css-page-3/#at-page-rule",
    "FIXME": "There are a lot more properties that are valid, see https://drafts.csswg.org/css-page-3/#properties-list",
    "descriptors": {
      "bleed": {
        "initial": "auto",
        "syntax": [
          "auto",
          "<length>"
        ]
      },
      "margin": {
        "initial": "0",
        "syntax": [
          "<'margin'>"
        ]
      },
      "margin-bottom": {
        "initial": "0",
        "syntax": [
          "<'margin-bottom'>"
        ]
      },
      "margin-left": {
        "initial": "0",
        "syntax": [
          "<'margin-left'>"
        ]
      },
      "margin-right": {
        "initial": "0",
        "syntax": [
          "<'margin-right'>"
        ]
      },
      "margin-top": {
        "initial": "0",
        "syntax": [
          "<'margin-top'>"
        ]
      },
      "marks": {
        "initial": "none",
        "syntax": [
          "none",
          "crop || cross"
        ]
      },
      "page-orientation": {
        "initial": "upright",
        "syntax": [
          "upright",
          "rotate-left",
          "rotate-right"
        ]
      },
      "size": {
        "initial": "auto",
        "FIXME": "Replace with actual syntax once we parse grammar properly",
        "syntax": [
          "<page-size>"
        ]
      }
    }
  },
  "property": {
    "spec": "https://drafts.css-houdini.org/css-properties-values-api/#at-property-rule",
    "descriptors": {
      "inherits": {
        "syntax": [
          "true",
          "false"
        ]
      },
      "initial-value": {
        "syntax": [
          "<declaration-value>?"
        ]
      },
      "syntax": {
        "syntax": [
          "<string>"
        ]
      }
    }
  },
  "counter-style": {
    "spec": "https://drafts.csswg.org/css-counter-styles/#the-counter-style-rule",
    "descriptors": {
      "system": {
        "initial": "symbolic",
        "syntax": [
          "<counter-style-system>"
        ]
      },
      "negative": {
        "initial": "-",
        "syntax": [
          "<counter-style-negative>"
        ]
      },
      "prefix": {
        "initial": "",
        "syntax": [
          "<symbol>"
        ]
      },
      "suffix": {
        "initial": ". ",
        "syntax": [
          "<symbol>"
        ]
      },
      "range": {
        "initial": "auto",
        "syntax": [
          "<counter-style-range>"
        ]
      },
      "pad": {
        "initial": "0 \"\"",
        "syntax": [
          "<counter-style-pad>"
        ]
      },
      "fallback": {
        "initial": "decimal",
        "syntax": [
          "<counter-style-name>"
        ]
      },
      "symbols": {
        "syntax": [
          "<symbol>+"
        ]
      },
      "additive-symbols": {
        "syntax": [
          "<counter-style-additive-symbols>"
        ]
      },
      "speak-as": {
        "initial": "auto",
        "syntax": [
          "auto",
          "bullets",
          "numbers",
          "words",
          "spell-out",
          "<counter-style-name>"
        ]
      }
    }
  },
  "function": {
    "spec": "https://drafts.csswg.org/css-mixins-1/#function-rule",
    "descriptors": {
      "result": {
        "allow-arbitrary-substitution-functions": true,
        "syntax": [
          "<declaration-value>?"
        ]
      }
    },
    "custom-descriptors": {
      "allow-arbitrary-substitution-functions": true,
      "syntax": [
        "<declaration-value>?"
      ]
    }
  }
}