#app-container {
    display: flex;
    min-height: 100vh;
    flex-direction: column;
    background: #343b59; /* Old browsers */
    background: -moz-linear-gradient(top, #343b59 0%, #3f487f 100%); /* FF3.6-15 */
    background: -webkit-linear-gradient(top, #343b59 0%,#3f487f 100%); /* Chrome10-25,Safari5.1-6 */
    background: linear-gradient(to bottom, #343b59 0%,#3f487f 100%); /* W3C, IE10+, FF16+, Chrome26+, Opera12+, Safari7+ */
    filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#343b59', endColorstr='#3f487f',GradientType=0 ); /* IE6-9 */
}

#app-container #content {
    flex: 1;
    display: flex;
    justify-content: center;
}

header {
    height: 64px;
    background: #23273c;
    color: white;
    line-height: 64px;
    padding-left: 10px;
}

.test {
    min-width: 50%;
    width: 500px;
    margin: 30px 15px;
    padding: 20px;
    display: flex;
    flex-direction: column;
}

footer {
    background: #23273c;
    text-align: center;
    color: white;
    padding: 10px;
}