.header{
    display: none;
}
.overlay{
    display: none;
}
@media screen and (max-width: 768px) {
.overlay {
    display: block;
    height: 100%;
    width: 100%;
    display: none;
    position: fixed;
    z-index: 1;
    top: 0;
    left: 0;
    background-color: rgb(0,0,0);
    background-color: rgba(0,0,0, 0.9);
}

.overlay-content {
    position: relative;
    top: 10%;
    width: 100%;
    text-align: center;
    margin-top: 30px;
}

.overlay a {
    padding: 8px;
    text-decoration: none;
    font-size: 36px;
    color: #818181;
    display: block;
    transition: 0.3s;
}
.overlay button{
    border: none;
    width: 100%;
    text-align: center;
    cursor: pointer;
    font-size: 32px;
    height: 80px; 
}
/* Change background color of buttons on hover */
.overlay button:hover {
    background-color: #a5a5a5;
}
  
  /* Create an active/current tablink class */
.overlay button.active {
    background-color: #a5a5a5;
}

.overlay a:hover, .overlay a:focus {
    color: #f1f1f1;
}

.overlay .closebtn {
    position: absolute;
    top: 20px;
    right: 45px;
    font-size: 60px;
}

@media screen and (max-height: 450px) {
  .overlay a {font-size: 20px}
  .overlay .closebtn {
    font-size: 40px;
    top: 15px;
    right: 35px;
  } 
}

.header {
    display: block;
    overflow: hidden;
    background-color: #ffffff;
    padding: 20px 10px;
  }
  
  .header a {
    float: left;
    color: black;
    text-align: center;
    padding: 12px;
    text-decoration: none;
    font-size: 18px; 
    line-height: 25px;
    border-radius: 4px;
  }
  
  .header a.logo {
    font-size: 25px;
    font-weight: bold;
  }
  
  .header a:hover {
    background-color: #ddd;
    color: black;
  }
  
  .header a.active {
    background-color: dodgerblue;
    color: white;
  }
  
  .header-right {
    float: right;
  }
}