*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body{
    width: 100%;
    height: 100vh;
    background: #000,#00d0ff;
    overflow: hidden;
}
.cursor{
    position: relative;
    width: 100px;
    height: 100px;
}
.cursor .circle{
position: absolute;
top: -50%;
left: -50%;
width: 100%;
height: 100%;
background: linear-gradient(#00d0ff,#ff005e);
border-radius: 50%;
}