diff -u b/core/modules/update/css/update.admin.theme.css b/core/modules/update/css/update.admin.theme.css
--- b/core/modules/update/css/update.admin.theme.css
+++ b/core/modules/update/css/update.admin.theme.css
@@ -61,23 +61,24 @@
 .project-update__version--recommended-strong .project-update__version-title {
   font-weight: bold;
 }
+
 .project-update__compatibility-details details {
   height: 20px;
   margin: 0;
   border: 0;
   background-color: inherit;
 }
-.project-update__compatibility-details details {
-  height: 20px;
-  margin: 0;
-  border: 0;
-  background-color: inherit;
+.project-update__compatibility-details details[open] {
+  overflow: visible;
+  height: auto;
+  white-space: normal;
 }
 project-update__compatibility-details details a {
   color: #5c5c5b;
   border: 0;
 }
 .project-update__compatibility-details details summary {
+  margin: 0;
   padding: 0;
   text-transform: none;
   font-weight: normal;
@@ -91,7 +92,8 @@
   color: #a51b00;
 }
 .project-update__compatibility-details details .details-wrapper {
-  padding: 0.25em 0 0 0;
+  margin: 0;
+  padding: 5px 0;
 }
 .project-update__compatibility-details .compatible .details-wrapper {
   color: #5c5c5b;
diff -u b/core/themes/stable/css/update/update.admin.theme.css b/core/themes/stable/css/update/update.admin.theme.css
--- b/core/themes/stable/css/update/update.admin.theme.css
+++ b/core/themes/stable/css/update/update.admin.theme.css
@@ -68,11 +68,17 @@
   border: 0;
   background-color: inherit;
 }
+.project-update__compatibility-details details[open] {
+  overflow: visible;
+  height: auto;
+  white-space: normal;
+}
 project-update__compatibility-details details a {
   color: #5c5c5b;
   border: 0;
 }
 .project-update__compatibility-details details summary {
+  margin: 0;
   padding: 0;
   text-transform: none;
   font-weight: normal;
@@ -86,7 +92,8 @@
   color: #a51b00;
 }
 .project-update__compatibility-details details .details-wrapper {
-  padding: 0.25em 0 0 0;
+  margin: 0;
+  padding: 5px 0;
 }
 .project-update__compatibility-details .compatible .details-wrapper {
   color: #5c5c5b;