In the zip package you would need to edit the html file on line 142. The code snippet below pasted at line 142 should render the result you are looking for.
if ((todaysDay == x) && (todaysDate == daycounter) && (todaysMonth == monthNum)) {
if (checkevents(daycounter,monthNum,yearNum,i,x))
{
calendarString += '<td align=\"center\" bgcolor=\"#9A45EE\" height=\"30\" width=\"40\"><a href=\"javascript:showevents(' + daycounter + ',' + monthNum + ',' + yearNum + ',' + i + ',' + x + ')\">' + daycounter + '<\/a><\/td>';
}
else
{
calendarString += '<td align=\"center\" bgcolor=\"#AAFFAA\" height=\"30\" width=\"40\"><a href=\"javascript:showevents(' + daycounter + ',' + monthNum + ',' + yearNum + ',' + i + ',' + x + ')\">' + daycounter + '<\/a><\/td>';
}
}
else calendarString += '<td align=\"center\" bgcolor=\"#FFFFC8\" height=\"30\" width=\"40\"><a href=\"javascript:showevents(' + daycounter + ',' + monthNum + ',' + yearNum + ',' + i + ',' + x + ')\">' + daycounter + '<\/a><\/td>';
}