style.css

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body{
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background: #2b2b2b;
 /* transition: 0.5s;*/
}
body.active{
    background: #f8f8f8;
}
#toggle{
    height: 160px;
    width: 320px;
    background: #222;
    appearance: none;
    border-radius: 160px;
    box-shadow: inset 0 8px 60px rgba(0,0,0,0.1),
                inset 0 8px 8px rgba(0,0,0,0.1),
                inset 0 -4px 4px rgba(0,0,0,0.1);
    position: relative;
    outline: none;
    cursor: pointer;
    transition: 0.5s;   
}
#toggle.active{
    background: #fff;
    box-shadow: inset 0 2px 60px rgba(0,0,0,0.1),
                inset 0 2px 8px rgba(0,0,0,0.1),
                inset 0 -4px 8px rgba(0,0,0,0.05);
}
#toggle .checkbox{
    height: 160px;
    width: 160px;
    position: absolute;
    top: 0;
    left: 0;
    content: "";
    background: linear-gradient(to bottom, #444, #222);
    border-radius: 50%;
    transform: scale(0.9);
    transition: 0.5s;
    box-shadow:0 8px 40px rgba(0,0,0,0.5),
               inset 0 4px 4px rgba(255, 255, 255,0.2),   
               inset 0 -4px 4px rgba(255, 255, 255,0.2); 
}
#toggle.active .checkbox{
    left: 160px;
    background: linear-gradient(to bottom, #eaeaea, #f9f9f9);
    box-shadow:0 8px 20px rgba(0,0,0,0.1),
    inset 0 4px 4px rgba(255, 255, 255,1),   
    inset 0 -4px 4px rgba(255, 255, 255,1); 
}