max-height and overflow not scrolling on ie9

Question

I have a very strange issue on ie9 where a div with a max-height (set with calc() and vh) and overflow auto is not scrolling.

You can see what is happening by clicking on this image (if the GIF does not load here):

My HTML:

<div class="modal">
  <div class="modal__title">Modal Title</div>
  <div class="modal__body">
    <p>When I am too tall, I should scroll on ie9, but I don't.</p>
  </div>
  <div class="modal__footer">Footer here</div>
</div> 

Relevant CSS:

.modal {
  min-width: 500px;
  max-width: 800px;
  border-radius: 4px;
  max-height: 65vh;
  overflow: hidden;
  background-color: white;
  position: fixed;
  top: 15vh;
  left: 50%;
  -webkit-transform: translateX(-50%);
  -ms-transform: translateX(-50%);
  transform: translateX(-50%);
}

.modal__body {
    max-height: calc(65vh - 120px)); // 120 is the combined height of the header and footer
    overflow-y: auto;
}

I don't understand why this is happening, as ie9 support vh, calc() and max-height. Any ideas?

JSFiddle Demo: https://jsfiddle.net/sbgg5bja/3/

Answer 1

It appears to be a repaint issue, when combining position: fixed and transform: translate.

Here is 2 possible fixes:

• Set the overflow property to scroll. I.e, overflow-y:scroll
• -ms-filter: "progid:DXImageTransform.Microsoft.Matrix(M11=1, M12=0, M21=0, M22=1, SizingMethod='auto expand')";

Src: How to solve IE9 scrolling repaint issue with fixed-position parent that has -ms-transform:translate?

If neither of these does it, you could drop the transform: translate and use for example display: table to center it.