html {
    height: 100%;
}
body {
    height: 100%;
    background-color: black;
}
.a-container {
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
}
.a-logo {
    max-width: 400px;
    padding:55px;
    flex:1;
}