CodePen Embed - jQuery

<div class="box"></div>

.box {
  width: 300px;
  height: 300px;
  background: red;
}

$(".box").on('click', function(){
  $(this).animate({
    "width": "500px",
    "opacity": ".3"
  }, 4000);
})

This Pen is owned by Alex on CodePen.

This Pen doesn't use any external CSS resources.