Fix the size of the buttons on mobile navigation.

user/themes/textbook/css/custom.css

@@ -81,4 +81,20 @@ section#header { z-index: 10; }
 
 iframe.geogebra {
     border: 1px dotted #a6a6a6;
-}
\ No newline at end of file
+}
+
+/** Fix Mobile Navigation **/
+
+.mobile-container ul.treemenu-root li span.toggler {
+    line-height: 2.22rem;
+    font-size: 2.22rem;
+    padding: 0.92rem 0.1rem;
+    margin: 0;
+}
+
+.mobile-container ul.treemenu-root li a {
+    line-height: 2.22rem;
+    font-size: 2.22rem;
+    padding: 0.92rem 1.618rem;
+    margin: 0;
+}