Issue #2486453 by LewisNyman, sqndr, heatherwoz, hylid, yoroy, Bojhan: Set maximum width on Seven

core/themes/seven/css/components/tabs.css

@@ -21,8 +21,8 @@
 /* Span the full width of the viewport */
 .content-header .is-horizontal .tabs:before,
 .content-header .is-collapse-enabled .tabs:before {
-  left: -2.5em;
-  right: -2.5em;
+  left: -99em;
+  right: -99em;
 }
 
 /**

core/themes/seven/css/layout/layout.css

@@ -4,3 +4,10 @@
 .page-content {
   margin-bottom: 80px;
 }
+
+@media all and (min-width: 75em) {
+  .layout-container {
+    width: 1170px;
+    margin: 0 auto;
+  }
+}