diff --git a/core/modules/system/css/system.admin.css b/core/modules/system/css/system.admin.css
index 7f23aab..6ef36af 100644
--- a/core/modules/system/css/system.admin.css
+++ b/core/modules/system/css/system.admin.css
@@ -79,6 +79,11 @@ small .admin-link:after {
 .system-modules thead > tr {
   border: 0;
 }
+.system-modules tbody {
+  display: table;
+  table-layout: fixed;
+  width: 100%;
+}
 .system-modules div.incompatible {
   font-weight: bold;
 }
@@ -100,6 +105,8 @@ small .admin-link:after {
 .system-modules details {
   color: #5c5c5b;
   line-height: 20px;
+}
+.system-modules details summary {
   overflow: hidden; /* truncates descriptions if too long */
   text-overflow: ellipsis;
   white-space: nowrap;
@@ -109,6 +116,9 @@ small .admin-link:after {
   overflow: visible;
   white-space: normal;
 }
+.system-modules details[open] > summary {
+  white-space: normal;
+}
 .system-modules details[open] summary .text {
   -webkit-hyphens: auto;
   -moz-hyphens: auto;