Using :after and :hover:after button in IE11 - css

Question

I have a button which is animated using :after and :hover:after CSS. Tried numerous ways to get it to work in IE but cannot find a work around. May be because the empty content:"", or the transition, but even without the transition is doesn't work. Any help / explanations is greatly appreciated.
button.bttnStyle1 {
background: none;
border: none;
font-size: 14rem;
text-transform: uppercase;
position: relative;
padding: 0rem;
cursor: pointer;
}
button.bttnStyle1:after,
button.bttnStyle1::after {
display: block;
position: absolute;
left: 0;
bottom: -5rem;
width: 3rem;
height: 3rem;
border-radius: 3rem;
content: "";
-o-transition: width 0.4s ease, height 2s ease-out;
-moz-transition: width 0.4s ease, height 2s ease-out;
-webkit-transition: width 0.4s ease, height 2s ease-out;
transition: width 0.4s ease, height 2s ease-out;
}
button.bttnStyle1:hover {}
button.bttnStyle1:hover:after,
button.bttnStyle1:hover::after {
width: 100%;
height: 2rem;
-o-transition: width 0.4s ease, height 2s ease-out;
-moz-transition: width 0.4s ease, height 2s ease-out;
-webkit-transition: width 0.4s ease, height 2s ease-out;
transition: width 0.4s ease, height 0.2s ease;
}
button.bttnStyle1:focus {
outline: none;
}
button.bttnColorGreen {
color: #69e0b1;
}
button.bttnColorGreen:after{
background-color:#69e0b1;
}
<button type="button" class="bttnStyle1 bttnColorGreen">BUTTON</button>
Codepen

Answer 1

Add overflow: visible; to your button. Found this solution here.

Answer 2

Solition:
CSS border radius need an actual border to be defined. Overflow also needed to be visible and everything works.
button.bttnStyle1:after,
button.bttnStyle1::after {
display: block;
position: absolute;
left: 0;
bottom: -5rem;
width: 0rem;
height: 0rem;
line-height:0;
border-radius:1rem;
content: "";
-o-transition: width 0.4s ease, height 2s ease-out;
-moz-transition: width 0.4s ease, height 2s ease-out;
-webkit-transition: width 0.4s ease, height 2s ease-out;
transition: width 0.4s ease, height 2s ease-out;
}
button.bttnColorGreen:after,
button.bttnColorGreen::after{
border:1rem solid #69e0b1;
background-color:#69e0b1;
}