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This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.


The ::-ms-expand CSS pseudo-element represents the button within a <select> that opens or closes the drop-down menu that displays the <option>s. It often normally looks like a triangle that points downward.


Not part of any specification.

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 Contributors to this page: jameshkramer, timothy-clifford, mfluehr, mrenty, kscarfone, cvrebert
 Last updated by: jameshkramer,