diff --git a/core/themes/claro/css/components/details.css b/core/themes/claro/css/components/details.css
index 0ec13ef256cfa50733d9ca0b6ec983958ea2aef8..9bdda2fe7d4c74946f2d7e8d14bb53c139d8e3cb 100644
--- a/core/themes/claro/css/components/details.css
+++ b/core/themes/claro/css/components/details.css
@@ -294,7 +294,7 @@ td .claro-details {
 
   .claro-details[open] > .claro-details__summary::before,
   [dir="rtl"] .claro-details[open] > .claro-details__summary::before {
-    margin-block-start: calc(0.125rem / -2);
+    margin-block-start: -0.125rem;
     margin-inline-end: 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 7e7afd803f06de7ec005c7c84f4e10381db588ea..17d24fe71f914369f0ee7aaa9f78322959e05064 100644
--- a/core/themes/claro/css/components/details.pcss.css
+++ b/core/themes/claro/css/components/details.pcss.css
@@ -276,7 +276,7 @@
 
   .claro-details[open] > .claro-details__summary::before,
   [dir="rtl"] .claro-details[open] > .claro-details__summary::before {
-    margin-block-start: calc(0.125rem / -2);
+    margin-block-start: -0.125rem;
     margin-inline-end: 0.125rem;
     transform: rotate(-45deg); /* for LTR and RTL */
     background: none;