モジュール:Message box/ambox.css

/* {{pp-template}} */
.ambox {
	border: 1px solid #a2a9b1;
	/* @noflip */
	border-left: 10px solid #36c;  /* Default "notice" blue */
	background-color: #fbfbfb;
	box-sizing: border-box;
}

/* Single border between stacked boxes. Take into account base templatestyles,
 * user styles, and Template:Dated maintenance category.
 * remove link selector when T200206 is fixed
 */
.ambox + link + .ambox,
.ambox + link + style + .ambox,
.ambox + link + link + .ambox,
/* TODO: raise these as "is this really that necessary???". the change was Dec 2021 */
.ambox + .mw-empty-elt + link + .ambox,
.ambox + .mw-empty-elt + link + style + .ambox,
.ambox + .mw-empty-elt + link + link + .ambox {
	margin-top: -1px;
}