diff --git a/core/themes/claro/css/components/details.css b/core/themes/claro/css/components/details.css
index 5090c8e68c..99f0452f27 100644
--- a/core/themes/claro/css/components/details.css
+++ b/core/themes/claro/css/components/details.css
@@ -310,7 +310,7 @@ td .claro-details {
 
   .claro-details[open] > .claro-details__summary::before,
   [dir="rtl"] .claro-details[open] > .claro-details__summary::before {
-    margin-top: calc(0.125rem / -2);
+    margin-top: -0.125rem;
     margin-right: 0.125rem;
     transform: rotate(-45deg); /* for LTR and RTL */
     background: none;
diff --git a/core/themes/claro/css/components/details.pcss.css b/core/themes/claro/css/components/details.pcss.css
index 9a94533343..b86425e9be 100644
--- a/core/themes/claro/css/components/details.pcss.css
+++ b/core/themes/claro/css/components/details.pcss.css
@@ -290,7 +290,7 @@
 
   .claro-details[open] > .claro-details__summary::before,
   [dir="rtl"] .claro-details[open] > .claro-details__summary::before {
-    margin-top: calc(0.125rem / -2);
+    margin-top: -0.125rem;
     margin-right: 0.125rem;
     transform: rotate(-45deg); /* for LTR and RTL */
     background: none;