/* The Overlay (background) */
  .overlay {
      /* Height & width depends on how you want to reveal the overlay (see JS below) */
      height: 100%;
      width: 0;
      position: fixed; /* Stay in place */
      z-index: 999999999; /* Sit on top */
      left: 0;
      top: 0;
      background-color: rgb(0,0,0); /* Black fallback color */
      background-color: rgba(0,0,0, 0.5); /* Black w/opacity */
      overflow-x: hidden; /* Disable horizontal scroll */
  }

  /* Position the content inside the overlay */
  .overlay-content {
      position: relative;
      top: 25%; /* 25% from the top */
      width: 100%; /* 100% width */
      text-align: center; /* Centered text/links */
      margin-top: 30px; /* 30px top margin to avoid conflict with the close button on smaller screens */
  }

  /* The navigation links inside the overlay */
  .overlay a {
      padding: 8px;
      text-decoration: none;
      font-size: 36px;
      color: #818181;
      display: block; /* Display block instead of inline */
      transition: 0.3s; /* Transition effects on hover (color) */
  }

  /* When you mouse over the navigation links, change their color */
  .overlay a:hover, .overlay a:focus {
      color: #f1f1f1;
  }

  /* Position the close button (top right corner) */
  .overlay .closebtn {
      position: absolute;
      top: 20px;
      right: 45px;
      font-size: 60px;
  }

  /* When the height of the screen is less than 450 pixels, change the font-size of the links and position the close button again, so they don't overlap */
  @media screen and (max-height: 450px) {
      .overlay a {font-size: 20px}
      .overlay .closebtn {
          font-size: 40px;
          top: 15px;
          right: 35px;
      }
  }