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

.container {
    width: 100%;
    height: 100%;
    background: linear-gradient(33deg, #0b3456, 33%, #636261);
}

.parent {
    display: flex;
    justify-content: center;
    align-items: center;
}
.child {
    
}