progid:DXImageTransform "Expecting anything but COLON"

[RedactedProfile]

.btn {
    filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#f0f2f5', endColorstr='#d1d9e1', GradientType=0);
}

Throws this exception

Parse error on line 1483:
...t-x; filter: progid:DXImageTransform.Mi
----------------------^
Expecting 'RIGHT_CURLY_BRACKET', 'SEMICOLON', 'COMMA', 'URL_FUNC', 'OPERATOR_NOT', 'LEFT_PARENTHESIS', 'RIGHT_PARENTHESIS', 'CALC_FUNC', 'ASTERISK', 'ASTERISK_WITH_WHITESPACE', 'PLUS_SIGN', 'HYPHEN_MINUS', 'SOLIDUS', 'IMPORTANT', 'REVERSE_SOLIDUS', 'NUMBER', 'HASH_STRING', 'HEXA_NUMBER', 'GENERAL_IDENT', 'SELECTOR_TYPE_WITH_WHITESPACE', 'SELECTOR_ID_WITH_WHITESPACE', 'DIMENSION', 'STRING', 'PERCENTAGE', 'VENDOR_PREFIX_IDENT', got 'COLON'
Error: Parse error on line 1483:
...t-x; filter: progid:DXImageTransform.Mi
----------------------^
Expecting 'RIGHT_CURLY_BRACKET', 'SEMICOLON', 'COMMA', 'URL_FUNC', 'OPERATOR_NOT', 'LEFT_PARENTHESIS', 'RIGHT_PARENTHESIS', 'CALC_FUNC', 'ASTERISK', 'ASTERISK_WITH_WHITESPACE', 'PLUS_SIGN', 'HYPHEN_MINUS', 'SOLIDUS', 'IMPORTANT', 'REVERSE_SOLIDUS', 'NUMBER', 'HASH_STRING', 'HEXA_NUMBER', 'GENERAL_IDENT', 'SELECTOR_TYPE_WITH_WHITESPACE', 'SELECTOR_ID_WITH_WHITESPACE', 'DIMENSION', 'STRING', 'PERCENTAGE', 'VENDOR_PREFIX_IDENT', got 'COLON'
    at Parser.parseError (C:\Users\djdar\AppData\Roaming\npm\node_modules\cssparser\lib\cssparser.js:434:21)
    at Parser.parse (C:\Users\djdar\AppData\Roaming\npm\node_modules\cssparser\lib\cssparser.js:501:22)
    at toJSON (C:\Users\djdar\AppData\Roaming\npm\node_modules\cssparser\lib\cli.js:58:22)
    at C:\Users\djdar\AppData\Roaming\npm\node_modules\cssparser\lib\cli.js:84:18
    at Object.<anonymous> (C:\Users\djdar\AppData\Roaming\npm\node_modules\cssparser\lib\cli.js:103:3)
    at Module._compile (internal/modules/cjs/loader.js:945:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:962:10)
    at Module.load (internal/modules/cjs/loader.js:798:32)
    at Function.Module._load (internal/modules/cjs/loader.js:711:12)
    at Function.Module.runMain (internal/modules/cjs/loader.js:1014:10)
undefined