MediaWiki:Vector.css

/* All CSS here will be loaded for users of the Vector skin */

/* reduce standard page width */
/* body:not(.vector-feature-wide-container-enabled) .vector-main-container,
/* body:not(.vector-feature-wide-container-enabled) .vector-content {
/*     max-width: 900px !important;
/*     margin: auto !important;
/* }

.vector-skin-standard .bodyContent {
    max-width: 900px !important;
    margin: 0 auto !important;
}