body {
    display: flex;
    flex-direction: column;
}

.main-area {
    flex-grow: 1;
}

@media (min-width: 450px) {
    .main-column {
        grid-area: mc;
    }
    .sidebar-first {
        grid-area: s1;
    }
    .sidebar-second {
        grid-area: s2;
    }
    .main-area__inside {
        display: grid;
        grid: "mc mc" "s1 s2" / 50% 50%;
    }
    .main-area--only-first-sidebar .main-area__inside {
        grid: "mc mc" "s1 s1" / 50% 50%;
    }
    .main-area--only-second-sidebar .main-area__inside {
        grid: "mc mc" "s2 s2" / 50% 50%;
    }
}

@media (min-width: 700px) {
    .main-area__inside {
        display: grid;
        grid: "mc s1" "mc s2" / minmax(440px, 1fr) minmax(220px, 280px);
        grid-template-rows: auto 1fr;
    }
    .main-area--only-first-sidebar .main-area__inside {
        grid: "mc s1" / minmax(440px, 1fr) minmax(220px, 280px);
    }
    .main-area--only-second-sidebar .main-area__inside {
        grid: "mc s2" / minmax(440px, 1fr) minmax(220px, 280px);
    }
}

@media (min-width: 1170px) {
    .main-area__inside {
        display: grid;
        grid: "s1 mc s2" / 22% 1fr 22%;
    }
    .main-area--only-first-sidebar .main-area__inside {
        grid: "s1 mc" / 280px 1fr;
    }
    .main-area--only-second-sidebar .main-area__inside {
        grid: "mc s2" / 1fr 280px;
    }
}