How to change the thickness of a circle with css? code example

Example 1: how to create a circle with css

<div id="circle">
</div>

#circle {
    width: 100px;
    height: 100px;
    background: red;
    border-radius: 50%
}

Example 2: cs cirlce

border: white solid 3px;
border-radius: 50%;
width:50px;
height:50px;