var text_size = 0;

function zoom_txt(act){
	var content_div   = document.getElementById('content');
	var current_class = content_div.className;
	var new_class = '';
	switch(current_class){
		case 'txt_-2':
			new_class = act == 'plus' ? 'txt_-1' : 'txt_-2';
			break;
		case 'txt_-1':
			new_class = act == 'plus' ? 'txt_0' : 'txt_-2';
			break;
		case 'txt_0':
			new_class = act == 'plus' ? 'txt_1' : 'txt_-1';
			break;
		case 'txt_1':
			new_class = act == 'plus' ? 'txt_2' : 'txt_0';
			break;
		case 'txt_2':
			new_class = act == 'plus' ? 'txt_2' : 'txt_1';
			break;
	}
	content_div.className = new_class;
}