diff --git a/core/themes/seven/css/layout/layout.css b/core/themes/seven/css/layout/layout.css
index eb7c2bf..6f60599 100644
--- a/core/themes/seven/css/layout/layout.css
+++ b/core/themes/seven/css/layout/layout.css
@@ -4,3 +4,45 @@
 .page-content {
   margin-bottom: 80px;
 }
+
+/**
+ * Copy layout definitions from system.admin.css for the case where Seven is used for non-admin pages.
+ */
+.layout-container {
+  margin: 0 1.5em;
+}
+.layout-container:after {
+  content: "";
+  display: table;
+  clear: both;
+}
+
+@media screen and (min-width: 38em) {
+  .layout-container {
+    margin: 0 2.5em;
+  }
+  .layout-column {
+    float: left;  /* LTR */
+    box-sizing: border-box;
+  }
+  [dir="rtl"] .layout-column {
+    float: right;
+  }
+  .layout-column + .layout-column {
+    padding-left: 10px; /* LTR */
+  }
+  [dir="rtl"] .layout-column + .layout-column {
+    padding-right: 10px;
+    padding-left: 0;
+  }
+  .layout-column.half {
+    width: 50%;
+  }
+  .layout-column.quarter {
+    width: 25%;
+  }
+  .layout-column.three-quarter {
+    width: 75%;
+  }
+}
+