style.css

body {
  padding: 8px;
  background-color: black;
  color: white;
  transition: margin-left .5s;
  font-size: 16px;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
  text-align: center;
  }

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

.sidenav {
   height: 100%;
   width: 0;
   position: fixed;
   z-index: 1;
   top: 0;
   left: 0;
   background-color: #111;
   overflow-x: hidden;
   transition: 0.5s;
   padding-top: 60px;
 }
 
 .sidenav a {
   padding: 8px 8px 8px 32px;
   text-decoration: none;
   font-size: 16px;
   color: #818181;
   display: block;
   transition: 0.3s;
 }
 
 .sidenav a:hover {
   color: #f1f1f1;
 }
 
 .sidenav .closebtn {
   position: absolute;
   top: 0;
   right: 25px;
   font-size: 36px;
   margin-left: 50px;
 }
 
 @media screen and (max-width: 512px) {
   .sidenav {padding-top: 15px;}
   .sidenav a {font-size: 18px;}
 }

 .myDiv {
  background-color: #222;
  text-align: center;
}

 .button {
  border: none;
  color: white;
  padding: 10px 26px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
  font-size: 14px;
  margin: 4px 2px;
  cursor: pointer;
}

.button1 {background-color: #4CAF50;} /* Green */

a:link {
  color: #4CAF50;
  background-color: transparent;
  text-decoration: none;
}
a:visited {
  color: #4CAF50;
  background-color: transparent;
  text-decoration: none;
}
a:hover {
  color: darkcyan;
  background-color: transparent;
  text-decoration: underline;
}
a:active {
  color: darkcyan;
  background-color: transparent;
  text-decoration: underline;
}

table {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
  border-collapse: collapse;
  width: 50%;
  margin-left:auto;
  margin-right:auto;
  text-align: center;
}

td, th {
  border: 1px solid #dddddd;
  text-align: left;
  padding: 8px;
}

tr:nth-child(even) {
  background-color: transparent;
}