{
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    "properties": {
      "custom-property": {
        "__compat": {
          "description": "--*",
          "mdn_url": "https://developer.mozilla.org/docs/Web/CSS/--*",
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            },
            "chrome": {
              "version_added": "49"
            },
            "chrome_android": {
              "version_added": "49"
            },
            "edge": {
              "version_added": "15"
            },
            "edge_mobile": {
              "version_added": "15"
            },
            "firefox": {
              "version_added": "29"
            },
            "firefox_android": {
              "version_added": "29"
            },
            "ie": {
              "version_added": false
            },
            "opera": {
              "version_added": "36"
            },
            "opera_android": {
              "version_added": "36"
            },
            "safari": {
              "version_added": true
            },
            "safari_ios": {
              "version_added": true
            },
            "samsunginternet_android": {
              "version_added": "5.0"
            }
          },
          "status": {
            "experimental": true,
            "standard_track": true,
            "deprecated": false
          }
        },
        "var": {
          "__compat": {
            "mdn_url": "https://developer.mozilla.org/docs/Web/CSS/var",
            "description": "<code>var()</code>",
            "support": {
              "webview_android": {
                "version_added": "50"
              },
              "chrome": [
                {
                  "version_added": "49"
                },
                {
                  "version_added": "48",
                  "flags": [
                    {
                      "type": "preference",
                      "name": "Enable experimental Web Platform features"
                    }
                  ]
                }
              ],
              "chrome_android": {
                "version_added": null
              },
              "edge": {
                "version_added": "15"
              },
              "edge_mobile": {
                "version_added": "15"
              },
              "firefox": [
                {
                  "version_added": "31"
                },
                {
                  "version_added": "29",
                  "version_removed": "55",
                  "notes": "From Firefox 29 until Firefox 31, this feature was implemented by the <code>var-variablename</code> syntax.",
                  "flags": [
                    {
                      "type": "preference",
                      "name": "layout.css.variables.enabled",
                      "value_to_set": "true"
                    }
                  ]
                }
              ],
              "firefox_android": [
                {
                  "version_added": "31"
                },
                {
                  "version_added": "29",
                  "version_removed": "55",
                  "notes": "From Firefox 29 until Firefox 31, this feature was implemented by the <code>var-variablename</code> syntax.",
                  "flags": [
                    {
                      "type": "preference",
                      "name": "layout.css.variables.enabled",
                      "value_to_set": "true"
                    }
                  ]
                }
              ],
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                "version_added": false
              },
              "opera": {
                "version_added": "36"
              },
              "opera_android": {
                "version_added": "37"
              },
              "safari": {
                "version_added": true
              },
              "safari_ios": {
                "version_added": true
              },
              "samsunginternet_android": {
                "version_added": null
              }
            },
            "status": {
              "experimental": true,
              "standard_track": true,
              "deprecated": false
            }
          }
        },
        "env": {
          "__compat": {
            "mdn_url": "https://developer.mozilla.org/docs/Web/CSS/env",
            "description": "<code>env()</code>",
            "support": {
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                {
                  "version_added": "11.1"
                },
                {
                  "version_added": "11",
                  "version_removed": "11",
                  "alternative_name": "constant"
                }
              ],
              "safari_ios": [
                {
                  "version_added": "11.1"
                },
                {
                  "version_added": "11",
                  "version_removed": "11",
                  "alternative_name": "constant"
                }
              ]
            },
            "status": {
              "experimental": true,
              "standard_track": true,
              "deprecated": false
            }
          }
        }
      }
    }
  }
}