.Jss function not supported in Titanium mobile SDK

I am trying to use .jss. but I do not know why it does not work. I have mywindow.js file and I created the file mywindow.jss.

in mywindow.jssfile

#b 
{
 width: 40;
 height: 50;
 color: '#324f85';
 font: {fontFamily: 'Helvetica-Bold', fontSize: 15};
}

at mywindow.js

var myButton = Titanium.UI.createButton({
id : "b",
title: 'clickME'

});

I do not know what I am doing wrong here.

Both .js and .jss files are in the same place. Using sdk 1.8.1