div {
 height: 100px;
 width: 100px;
 border-radius: 50%;
 margin: auto;
 margin-bottom: 10px; 
}

#red-box {
 background: red; 
}

#orange-box {
 background: orange; 
}

#yellow-box {
 background: radial-gradient(pink, yellow); 
}

#green-box {
 background: radial-gradient(cyan, green); 
}

#blue-box {
 background: blue; 
}

#violet-box {
 background: violet; 
}