body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
}

.topnav {
  overflow: hidden;
  background-color: #333;
}

.topnav a {
  float: left;
  color: #f2f2f2;
  text-align: center;
  padding: 24px 26px;
  text-decoration: none;
  font-size: 17px;
}

.topnav a:hover {
  background-color: #4CAF50;
  color: white;
}

.topnav a.active {
  background-color: #4CAF50;
  color: black;
}

th, td {
    border: 1px solid black;
    padding: 10px;
}
button {
	font-size: 25px;
	cursor: pointer;
}