Created a beter text_resize.js

Hope this helps

// $Id $
Drupal.behaviors.textResize = function(context) {

	var resizeScope = 1.1;

  // Which div or page element are we resizing?
  if (text_resize_scope) { // Admin-specified scope takes precedence.
    if ($('#'+text_resize_scope).length > 0) {
      var element_to_resize = $('#'+text_resize_scope); // ID specified by admin
    }
    else if ($('.'+text_resize_scope).length > 0) {
      var element_to_resize = $('.'+text_resize_scope); // CLASS specified by admin
    }
    else {
      var element_to_resize = $(text_resize_scope); // It's just a tag specified by admin
    }
	}
	else { // Look for some default scopes that might exist.
    if ($('DIV.left-corner').length > 0) {
      var element_to_resize = $('DIV.left-corner'); // Main body div for Garland
    }
    else if ($('#content-inner').length > 0) {
      var element_to_resize = $('#content-inner'); // Main body div for Zen-based themes
    }
    else if ($('#squeeze > #content').length > 0) {
      var element_to_resize = $('#squeeze > #content'); // Main body div for Zen Classic
    }
	}
  // Set the initial font size if necessary
  if ($.cookie('text_resize') != null) {
    element_to_resize.css('font-size', parseFloat($.cookie('text_resize')) + 'px');
    //alert( "Should be size: " + $.cookie('text_resize'));
  }
  else {
    //alert('Couldn\'t find text_resize cookie.');
  }
  if (text_resize_line_height_allow) {
    //alert('line height adjustment allowed! The current line-height is '+parseFloat(element_to_resize.css('line-height'), 10));
		// Set the initial line height if necessary
    if ($.cookie('text_resize_line_height') != null) {
      element_to_resize.css('line-height', parseFloat($.cookie('text_resize_line_height')) + 'px');
    }
	}
  // Changer links will change the text size when clicked
  $('a.changer').click(function() {
   resize(this);
  });
  
  function resize (changer) {
	  // Set the current font size of the specified section as a variable
	  var current_font_size = parseFloat(element_to_resize.css('font-size'), 10);

		// Set the current line-height
		var current_line_height = parseFloat(element_to_resize.css('line-height'), 10);
		
		// Pre define vars
		var new_font_size 		= false;
		var new_line_height 	= false;
		
		var allow_change 			= false;
		
		var reset_size_max 		= false
		var reset_size_min 		= false;
	 	var reset_size_null 	= false;
	 	
	  // javascript lets us choose which link was clicked, by ID
	  if (changer.id == 'text_resize_increase') {
	    font_increase();
	  }
	  else if (changer.id == 'text_resize_decrease') {
	    font_decrease();
	  }
	  else if (changer.id == 'text_resize_reset') {
	  	set_cookie_sizes(null, null);
	    reset_size_null = true;
	  }
	  
	  // jQuery lets us set the font size value of the main text div
	  if (allow_change == true) {
	  	return set_font_size(new_font_size, new_line_height);
		} else if (reset_size_null == true) {
	  	return set_font_size(null, null)
	  } else if (reset_size_min == true) {
	  	return set_font_size(text_resize_minimum, text_resize_line_height_min);
	  } else if (reset_size_max == true) {
	  	return set_font_size(text_resize_maximum, text_resize_line_height_max);
	  }
		
		function font_increase () {
			
			new_font_size = current_font_size * resizeScope;
    	new_line_height = current_line_height * resizeScope; 
    	
	    // Allow resizing as long as font size doesn't go above text_resize_maximum.
	    
	    if (new_font_size <= text_resize_maximum) {
	    
	    	//alert(new_font_size +' > '+ text_resize_maximum);
				set_cookie_sizes(new_font_size, new_line_height);
	      allow_change = true;
	    }
	    else {
				set_cookie_sizes(text_resize_maximum, text_resize_line_height_max);
      	reset_size_max = true;
			}
		}
		
		function font_decrease () {
			
			new_font_size = current_font_size / resizeScope;
			new_line_height = current_line_height / resizeScope;
			
	    if (new_font_size >= text_resize_minimum) {
	      // Allow resizing as long as font size doesn't go below text_resize_minimum.
				set_cookie_sizes(new_font_size, new_line_height);
	      allow_change = true;
	    }
	    else {
	      // If it goes below text_resize_minimum, just leave it at text_resize_minimum.
				set_cookie_sizes(text_resize_minimum, text_resize_line_height_min);
	      reset_size_min = true;
	    }
		}
		
		function set_cookie_sizes(text_size, line_height) {
			
			$.cookie('text_resize', text_size, { path: '/' });
			
			if (text_resize_line_height_allow)
				$.cookie('text_resize_line_height', line_height, { path: '/' });
		}
	  
	  function set_font_size (font_size, line_height) {
	  	
	  	// add + px if input is different than null
	  	if (font_size != null && line_height != null) {
	  		font_size = font_size + 'px';
	  		line_height = line_height + 'px';
			}
				  
	    element_to_resize.css('font-size', font_size);
			if (text_resize_line_height_allow)
				element_to_resize.css('line-height', line_height + 'px');
			return false;
	  }
  }
}