Stacking Divs from Bottom to Top

All the answers miss the scrollbar point of your question. And it’s a tough one. If you only need this to work for modern browsers and IE 8+ you can use table positioning, vertical-align:bottom and max-height. See MDN for specific browser compatibility.

Demo (vertical-align)

.wrapper {
  display: table-cell;
  vertical-align: bottom;
  height: 200px;
}
.content {
  max-height: 200px;
  overflow: auto;
}

html

<div class="wrapper">
  <div class="content">
     <div>row 1</div>
     <div>row 2</div>
     <div>row 3</div>  
  </div>
</div>  

Other than that, I think it’s not possible with CSS only. You can make elements stick to the bottom of their container with position:absolute, but it’ll take them out of the flow. As a result they won’t stretch and make the container to be scrollable.

Demo (position-absolute)

.wrapper {
  position: relative;
  height: 200px;
}
.content {
  position: absolute;
  bottom: 0;
  width: 100%;
}