I have designed a pop up style window, which has a title bar & content section. Inside, the content section I have put a button too. I am trying to change the background color of title bar. I have made two classes (`title_bar` & `title_bar_hover`) which contain `background: linear-gradient();` property only. 
As per the solution given in this stackoverflow [thread](https://stackoverflow.com/questions/18305080/change-background-color-of-div) I have wrote the following jquery. I have added `jquery-ui` plugin as well.

```
$('#start').on('hover',function(){
    var target = $('.title_bar');
    target.addClass(".title_bar_hover");
},5);

```

But this code is unable to perform anything. However, here is the sample [jsfiddle](http://jsfiddle.net/hitek_guy/8fPep/).
So please suggest some way(s) to achieve this functionality.  

Thank you so much!