main {
    width: 50%;
    margin-left: calc(25% - 1.5px);
    margin-right: calc(25% - 6.5px);
}

article {
    text-align: center;
}

@media screen and (max-width: 1000px) {
    main {
        width: calc(100% - 90px);
        margin-left: 20px;
        margin-right: 20px;
    }
}