.modal_window {
     position: absolute;
     top: 0;
     left: 0;
     margin: 0;
     padding: 0;
     background: #fff;
     width: 100%;
     min-height: 100%;
     z-index: 999;
 }
 .modal_window.centered {
     display: flex;
     flex-direction: column;
     align-items: center;
     justify-content: center;
     text-align: center;
 }
 .modal_window > article {
     margin: 3%;
 }
 .modal_window.centered div {
     display: flex;
     flex-wrap: wrap;
 }
 .modal_window.centered button {
     flex-grow: 1;
 }
 .modal_window#alert {
     position: fixed;
 }
 .modal_window#alert h2 {
     font-size: 2.5em;
     margin: 0;
     padding: 0;
     margin-bottom: 0.75em;
 }
 .modal_window#alert button {
     padding-left: 2em;
     padding-right: 2em;
 }