@media screen and (max-width: 600px) {

  #header {
    height: 150px;
  }
  
  #header h1 {
    display: none;
  }
  
  .grid .book {
    width: 100%;
    margin-right: 0;
  }
  
  #login.section {
    text-align: left;
  }
  
  #login.section h2::after {
    margin: 15px 0 30px 0;
  }
  
  .popup {
    position: absolute;
    top: 47px;
    left: 0;
    right: 0;
    width: 100%;
  }
  
  .top_header .logout {
    display: none;
  }
  
  #menu {
    float: none;
    position: relative;
  }
  
  #menu .mobile_menu_button {
    float: right;
    display: block;
    cursor: pointer;
  }
  
  #menu .mobile_menu_button:hover {
    color: #d9374f;
  }
  
  #menu .mobile_menu_button.active ~ ul {
    display: block;
  }
  
  #menu ul li.mobile_only {
    display: block;
  }
  
  #menu ul {
    display: none;
    background: #ece9f3;
    position: absolute;
    top: 39px;
    right: -16px;
  }
  
  #menu ul li {
    display: block;
    margin: 0;
  }
  
  #menu ul li a {
    padding: 0 15px;
    color: #404b69;
    display: block;
  }
  
  #menu ul li a i {
    display: none;
  }
  
  #menu::before {
    content: "\f56b";
    font-family: "Font Awesome 5 Free";
    font-weight: bold;
  }
  
  .top_header {
    overflow: visible;
  }
  
}