--- a/browser/themes/shared/tabs.inc.css
+++ b/browser/themes/shared/tabs.inc.css
@@ -352,17 +352,17 @@ tabbrowser {
 }
 
 .tab-label {
   margin-inline-end: 0;
   margin-inline-start: 0;
 }
 
 .tab-close-button {
-  margin-inline-end: -2px;
+  margin-inline-end: -1px;
   padding: 0;
   -moz-context-properties: fill, fill-opacity, stroke-opacity;
   stroke-opacity: var(--toolbarbutton-icon-fill-opacity);
 }
 
 :root[uidensity=touch] .tab-close-button {
   margin-inline-end: -@horizontalTabPadding@;
   padding: 10px calc(@horizontalTabPadding@ - 2px);