Change Style Class By Changing Scoped Variable Value

I have a button inside an xpages div and I am trying to compute the style class of that button based on a scoped variable. Initially, the scoped variable's value is 'blue' and the

Solution 1:

if you disable the theme for the button it should work

<xp:button id="btn" disableTheme="true"></xp:button>    

Solution 2:

Please don't compare Java Strings like that, use .equals("...") instead.