diff --git a/userChrome.css b/userChrome.css
index 8cea7ae..a999701 100644
--- a/userChrome.css
+++ b/userChrome.css
@@ -41,6 +41,21 @@
     width: 25px; /* Original: 40px */
   }
 
+  :root {
+    --newtab-button-minus-width-padding: 2px;
+    --newtab-button-width-padding: calc(var(--toolbarbutton-inner-padding) - var(--newtab-button-minus-width-padding));
+  }
+  #tabs-newtab-button > .toolbarbutton-icon,
+  #new-tab-button     > .toolbarbutton-icon,
+  #alltabs-button     > .toolbarbutton-badge-stack {
+    /* Original: calc(2 * var(--toolbarbutton-inner-padding) + 16px) */
+    width: calc(2 * var(--newtab-button-width-padding) + 16px);
+
+    /* Original: --toolbarbutton-inner-padding */
+    padding-left:  var(--newtab-button-width-padding);
+    padding-right: var(--newtab-button-width-padding);
+  }
+
   :root[uidensity=compact] #tabbrowser-tabs[haspinnedtabs]:not([positionpinnedtabs]) > #tabbrowser-arrowscrollbox > .tabbrowser-tab[first-visible-unpinned-tab] {
     margin-inline-start: 0 !important;
   }