.buttons {
    margin-top: 20px;
}
.grid article {
    margin: auto;
}
@media (min-width: 768px) {
    .grid article {
        max-width: 400px;
    }
}
@media (max-width: 767px) {
    .grid article {
        max-width: 200px;
    }
}
.assignment-container {
    margin-top: 20px;
}