Here is my CSS:

```
.animate-rectangle {
    background-color:#0F0;
    border: 1px solid #FFF;
    float:left;
    position:absolute;
    width:100px;
    height:100px;
}

```

And the jQuery codes:

```
<!--Jquery Code to Animate Rectangle from Left to Right-->
$(document).ready(function () {

    var windo_width = $(document).width() - 300;

    $("#reset").click(function () {
        $(".animate-rectangle").animate({
            "left": "100px"
        }, "slow");
    });

    $("#MoveRight").click(function () {
        $(".animate-rectangle").animate({
            "left": "+=" + windo_width
        }, "slow");
    });

});

```

Look at jQuery codes it declares that `animate({"left":"100px"}` but in action it goes right why this happend?