.avatar {
    width: 50px;
    height: 50px;
    border: 1px solid white;
    border-radius: 50%;
    background: url(https://pbs.twimg.com/profile_images/600314410003865600/laIuu4bB.jpg);
    background-size: cover;
    box-shadow: 0 0.5px 2px rgba(0,0,0,0.5);
    box-sizing: border-box;
    cursor: pointer;
}