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
@@ -76,28 +76,13 @@
-project-update__compatibility-details details a {
-  color: #5c5c5b;
-  border: 0;
-}
 .project-update__compatibility-details details summary {
   margin: 0;
   padding: 0;
+  border: 0;
+  color: #5c5c5b;
   text-transform: none;
   font-weight: normal;
 }
-.project-update__compatibility-details details.compatible summary,
-.project-update__compatibility-details details[open].compatible summary {
-  color: green;
-}
-.project-update__compatibility-details details.not-compatible summary,
-.project-update__compatibility-details details[open].not-compatible summary {
-  color: #a51b00;
-}
 .project-update__compatibility-details details .details-wrapper {
   margin: 0;
   padding: 5px 0;
-}
-.project-update__compatibility-details .compatible .details-wrapper {
   color: #5c5c5b;
 }
-.project-update__compatibility-details .not-compatible .details-wrapper {
-  color: #a51b00;
-}
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
@@ -76,28 +76,13 @@
-project-update__compatibility-details details a {
+.project-update__compatibility-details details summary {
   color: #5c5c5b;
   border: 0;
-}
-.project-update__compatibility-details details summary {
   margin: 0;
   padding: 0;
   text-transform: none;
   font-weight: normal;
 }
-.project-update__compatibility-details details.compatible summary,
-.project-update__compatibility-details details[open].compatible summary {
-  color: green;
-}
-.project-update__compatibility-details details.not-compatible summary,
-.project-update__compatibility-details details[open].not-compatible summary {
-  color: #a51b00;
-}
 .project-update__compatibility-details details .details-wrapper {
   margin: 0;
   padding: 5px 0;
-}
-.project-update__compatibility-details .compatible .details-wrapper {
   color: #5c5c5b;
 }
-.project-update__compatibility-details .not-compatible .details-wrapper {
-  color: #a51b00;
-}