diff --git a/custom-browser-pane-margin-and-rounding.css b/custom-browser-pane-margin-and-rounding.css
new file mode 100644
index 0000000..fc31147
--- /dev/null
+++ b/custom-browser-pane-margin-and-rounding.css
@@ -0,0 +1,19 @@
+/* Add slight margin, rounding and outline to Browser pane */
+#tabbrowser-tabbox browser {
+   --border-size: 0.5px;
+   --margin-size-top-left: 2px;
+   --margin-size-bottom-right: 6px;
+   --rounding-size: 8px;
+
+   border: var(--border-size) solid rgba(255,255,255,0.15);
+   margin: var(--margin-size-top-left) var(--margin-size-bottom-right) var(--margin-size-bottom-right) var(--margin-size-top-left);
+   border-radius: var(--rounding-size);
+}
+
+.browserContainer {
+   background: var(--toolbox-bgcolor);
+
+   &:-moz-window-inactive {
+      background: var(--toolbox-bgcolor-inactive);
+   }
+}