Inner border-radius

HTML

<div>
    <span id="bottom-left"></span>
    
   
</div>

CSS

body {
    margin: 20px;
    background:white;
}
div {
    position:relative;
    margin:0 auto; 
    background:green;
    min-height:80px;
    padding:40px;
}
div:before {
    content:'';
    display:block;
    width:0;
    height:0;
    position:absolute;
    top:-40px;
    left:-40px;
    border-left: 40px solid transparent;
    border-bottom: 40px solid transparent;
    border-top: 40px solid transparent;
    border-right: 40px solid white;
    border-radius:40px;
    -moz-transform: rotate(45deg);
    -ms-transform: rotate(45deg);
    -webkit-transform: rotate(45deg);
    -o-transform: rotate(45deg);
    transform: rotate(45deg);
}
div:after {
    content:'';
    display:block;
    width:0;
    height:0;
    position:absolute;
    top:-40px;
    right:-40px;
    border-left: 40px solid red;
    border-bottom: 40px solid transparent;
    border-top: 40px solid transparent;
    border-right: 40px solid transparent;
    border-radius:40px;
    -moz-transform: rotate(-45deg);
    -ms-transform: rotate(-45deg);
    -webkit-transform: rotate(-45deg);
    -o-transform: rotate(-45deg);
    transform: rotate(-45deg);
}
#bottom-right {
    content:'';
    display:block;
    width:0;
    height:0;
    position:absolute;
    bottom:-40px;
    right:-40px;
    border-left: 40px solid white;
    border-bottom: 40px solid transparent;
    border-top: 40px solid transparent;
    border-right: 40px solid transparent;
    border-radius:40px;
    -moz-transform: rotate(45deg);
    -ms-transform: rotate(45deg);
    -webkit-transform: rotate(45deg);
    -o-transform: rotate(45deg);
    transform: rotate(45deg);
}
#bottom-left {
    content:'';
    display:block;
    width:0;
    height:0;
    position:absolute;
    bottom:-40px;
    left:-40px;
    border-left: 40px solid transparent;
    border-bottom: 40px solid transparent;
    border-top: 40px solid transparent;
    border-right: 40px solid white;
    border-radius:40px;
    -moz-transform: rotate(-45deg);
   ...