.box{
    width: 200px;
    height: 200px;
    border: 2px solid cyan;
    position: relative;
}

.item{
    width: 50px;
    height: 50px;
    background-color: #F00;
    border: 2px solid cyan;
    border-radius: 50%;
    position: absolute;
    top: 30px;
    right: 30px;
}