body {
     transition: 0.3s;
     font-family: sans-serif, Arial;
     text-align: center;
     padding-top: 50px;
 }

 #toggleBtn {
     padding: 10px 20px;
     font-size: 16px;
     border: none;
     border-radius: 5px;
     cursor: pointer;
 }

 .dark {
     background: #111;
     color: #fff;
 }