fix(mobile): bar buttons answer a 44pt square

Back, More, Close and the pane's round buttons are drawn at 38pt and took
taps only there, under the 44pt a finger is owed. Each now answers a 44pt
square around the same drawing.

mobile/src/style.css

@@ -2821,3 +2821,19 @@ html[data-nav="pop"]::view-transition-new(root) {
   inset: 0;
   z-index: 8;
 }
+
+/* The round bar buttons are drawn at 38pt but answer a 44pt square, the
+   least a finger should have to hit. */
+.round,
+.nav-icon,
+.nav-back {
+  position: relative;
+}
+
+.round::before,
+.nav-icon::before,
+.nav-back::before {
+  content: "";
+  position: absolute;
+  inset: -3px;
+}