how to change progressbar color ?

[er.viveksrivastava]

I want to change progress bar color. In given code?

<rich:progressBar mode="client" id="progressBar" style="width:250px;height:20px;"  >

            <f:facet name="initial">

                <h:outputText value="Process doesn't started yet"/>

            </f:facet>

            <f:facet name="complete">

                <h:outputText value="Process Done"/>

            </f:facet>

          </rich:progressBar>