Q:

Internet explorer 11 shows background when using border-radius

The IE 11 (11.0.9600.18350) seems to have some issues when using rounded borders. I made a minimal fiddle: https://jsfiddle.net/7phqrack/2/
html:
<div class="backgrounddiv">
  <div class="outer">
    <span id="span1">some content</span>
    <div class="inner">
      <span id="span2">more content in a nested div</span>
    </div>
  </div>
  <div class="outer">
    <span id="span1">some other content</span>
  </div>
</div>

style:
.backgrounddiv{
  background: black;
}
.outer{
  border-radius: 4px 4px 0px 0px;
  background: white;
}
.inner{
  background: white;

}

At some zoomlevels (130% on my machine) the background is visible between the two divs (and also at the upper border). Other browsers do not render the black line between the divs.

Does anybody know how to solve this issue?

A:

This question was already asked:

Question 1
Question 2

It seems to be a bug in IE11.

