body.dark-mode {
      background-color: black;
      color: white;
    }
    
    body.light-mode {
      background-color: white;
      color: black;
    }


    p::selection {
      background-color: red;
    }

    .underline-link {
      text-decoration: underline;
    }

 .switch {
      position: relative;
      display: inline-block;
      width: 50px;
      height: 25px;
    }

    .switch input { 
      opacity: 0;
      width: 0;
      height: 0;
    }

    .slider {
      position: absolute;
      cursor: pointer;
      top: 0;
      left: 0;
      right: 0;
      bottom: 0;
      background-color: #ccc;
      -webkit-transition: .4s;
      transition: .4s;
      border-radius: 25px;
    }

    .slider:before {
      position: absolute;
      content: "";
      height: 21px;
      width: 21px;
      left: 2px;
      bottom: 2px;
      background-color: white;
      -webkit-transition: .4s;
      transition: .4s;
      border-radius: 50%;
    }

    input:checked + .slider {
      background-color: #4cd964;
    }

    input:focus + .slider {
      box-shadow: 0 0 1px #4cd964;
    }

    input:checked + .slider:before {
      -webkit-transform: translateX(25px);
      -ms-transform: translateX(25px);
      transform: translateX(25px);
    }