.ex1{
    border-radius:1em;
}
.ex2{
    border-radius:2em;
}
.ex3 {
    border-top-left-radius: 2em;
}
.ex4 {
    border-radius: 1em 2em 3em 4em;
}

.ex5 {
    width:20rem;
    height:20rem;
    line-height:12.5rem;
    border-radius: 50%;
    text-align:center;
    padding:0;
    white-space:nowrap;
}

.ex6 {
    width:0;
    height:0;
    border-radius:50%;
    border-top: 10rem solid #ff00d7;
    border-left: 10rem solid #d16bff;
    border-bottom: 10rem solid purple;
    border-right: 10rem solid #ff8bf6;
}