About specialEasing.

If you're trying to animate font size using special per-property easing it won't work.
For example:
  $("span").animate({
    font-size:'2em'
  }, {
    duration: 1000,
    specialEasing: {
      'font-size': 'special'
    }
  }); 

A conflict is between 
    5328   var name = p.replace(rdashAlpha, fcamelCase);
and
    5618   var specialEasing = this.options.specialEasing && this.options.specialEasing[this.prop];

this.prop will be 'fontSize' instead of 'font-size' but 'fontSize' is not a CSS name.

This will work:
  $("span").animate({
    font-size:'2em'
  }, {
    duration: 1000,
    specialEasing: {
      'fontSize': 'special'
    }
  }); 

Sorry for my awful english.