diff --git a/integrations/nextcloud/snappymail/app/themes/Nextcloud25/styles.css b/integrations/nextcloud/snappymail/app/themes/Nextcloud25/styles.css
index 62a0e5039..537089b37 100644
--- a/integrations/nextcloud/snappymail/app/themes/Nextcloud25/styles.css
+++ b/integrations/nextcloud/snappymail/app/themes/Nextcloud25/styles.css
@@ -437,6 +437,7 @@ select option {
 }
 
 .e-checkbox.material-design>div {
+    box-sizing: border-box !important;
     border: 2px solid var(--color-primary-element);
     border-radius: 2px;
     box-sizing: border-box;