code: function(_value,_prop){
  		    if(_prop === 'filter'){
  		      _value = _u._$fixed(_value,0);
  		      _value = 'alpha(opacity=' + _value + ')';
  		    }
  		    if(_prop === 'z-index')
  		      _value = _u._$fixed(_value,0);
  		    return _value;
  		  }
docs: 适配特殊属性