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.single-post .site-main { max-width: 100%; !important }
.single-post .c-sidebar { display: none; }
@media screen and (min-width: 1024px) {
    body.single-sidebar .site-main {
        max-width: 100%;
    }
}
@media screen and (min-width: 1200px) {
    body.no-sidebar .site-main {
        max-width: 100%;
    }
    body.single-sidebar .site-main {
        max-width: 100%;
    }
}