.overlay {
  height: 100%;
  width: 0; /* Width is 0 when closed */
  position: fixed;
  z-index: 1;
  top: 0;
  left: 0;
  background-color: #003f88;
  opacity: 0.9;
  overflow-x: hidden;
  transition: 0.5s;
}

.overlay-content {
  position: relative;
  top: 25%;
  width: 100%;
  text-align: center;
  margin-top: 30px;
}

.overlay a {
  padding: 8px;
  text-decoration: none;
  font-size: 36px;
  color: white;
  display: block; /* Make the links block elements */
  transition: 0.3s;
}

.overlay a:hover, .overlay a:focus {
  color: #fdc500;
}

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

/* Submenu styles */
.submenu {
  display: none; /* Initially hidden */
  margin-left: 30px; /* Indent submenu items */
}

.submenu a {
  font-size: 28px; /* Smaller font size for submenu items */
}

/* Style for the '+' or '-' sign */
.submenu-toggle .submenu-sign {
  margin-left: 10px;
  font-size: 28px;
}

/* Remove the underline from the submenu-toggle link */
.submenu-toggle {
  text-decoration: none;
  cursor: pointer;
}

@media screen and (max-height: 450px) {
  .overlay a {font-size: 20px}
  .overlay .closebtn {
    font-size: 40px;
    top: 15px;
    right: 35px;
  }
  .submenu a {
    font-size: 18px;
  }
  .submenu-toggle .submenu-sign {
    font-size: 18px;
  }
}