When using the DialogActionBar, its flex CSS property is flex:1 0 0.  For some reason, this is not a valid value in IE11, and I need to specify the flex values explicitly:

.k-dialog-button-layout-stretched .k-button {
    flex-grow: 1;
    flex-shrink: 0;
    flex-basis: 0px;
}

Can this be added to the original stylesheet so it works out of the box?