function fontsizeup()
{
var active = getActiveStyleSheet();

switch (active)
{
case 'A--':
setActiveStyleSheet('A-');
break;

case 'A-':
setActiveStyleSheet('A');
break;

case 'A':
setActiveStyleSheet('A+');
break;

case 'A+':
setActiveStyleSheet('A++');
break;

case 'A++':
setActiveStyleSheet('A');
break;

default:
setActiveStyleSheet('A');
break;
}
}