To change the color of the text displayed in the module, use this CSS code below:
 
.ClockTZ
{
    color: white;
    border-top: thin white solid;
    border-bottom: thin #AAA solid;
}
 
.TZLabel
{
    font: 65%;
    font-weight: bold;
    color:#AAA;
}
 
To hide the UTC offset, you need to set the display to 'none.'  In versions up to 1.2.3 there is an issue in the HTML code generated by the module that doesn't affects the class for the UTC, so we'll use a different selector to get at it.

.ClockTZ
.TZName SPAN
{
     display:none;
}