rustdoc: use CSS margin/padding shorthand when all are being set

Author: notriddle

src/librustdoc/html/static/css/rustdoc.css

@@ -493,9 +493,7 @@ ul.block, .block li {
 .sidebar h2 {
 	overflow-wrap: anywhere;
 	padding: 0;
-	margin: 0;
-	margin-top: 0.7rem;
-	margin-bottom: 0.7rem;
+	margin: 0.7rem 0;
 }
 
 .sidebar h3 {
@@ -805,10 +803,8 @@ table,
 }
 #crate-search {
 	min-width: 115px;
-	padding: 0;
 	/* keep these two in sync with "@-moz-document url-prefix()" below */
-	padding-left: 4px;
-	padding-right: 23px;
+	padding: 0 23px 0 4px;
 	/* prevents the <select> from overflowing the containing div in case it's shrunk */
 	max-width: 100%;
 	/* contents can overflow because of max-width limit, then show ellipsis */
@@ -1724,7 +1720,6 @@ in storage.js
 		/* Hide the sidebar offscreen while not in use. Doing this instead of display: none means
 		   the sidebar stays visible for screen readers, which is useful for navigation. */
 		left: -1000px;
-		margin-left: 0;
 		margin: 0;
 		padding: 0;
 		z-index: 11;
@@ -1777,9 +1772,7 @@ in storage.js
 	.mobile-topbar .logo-container > img {
 		max-width: 35px;
 		max-height: 35px;
-		margin-left: 20px;
-		margin-top: 5px;
-		margin-bottom: 5px;
+		margin: 5px 0 5px 20px;
 	}
 
 	.mobile-topbar {