html, body {
    height: 100%;
    margin: 0 0;
}

body {
    display: flex;
    justify-content: space-between;
    align-items: stretch;
}

.stripes {
    flex: 1;
    background: repeating-linear-gradient(
        45deg,
        #606dbc,
        #606dbc 10px,
        #465298 10px,
        #465298 20px
    );
}

.container {
    padding: 8px;
    flex: 4;
}