Fix overflow in settings page (#805)

bookmarks/styles/settings.scss

@@ -7,8 +7,9 @@
     }
   }
 
-  textarea.custom-css {
+  textarea.monospace {
     font-family: monospace;
+    box-sizing: border-box;
   }
 
   .input-group > input[type=submit] {

bookmarks/styles/spectre.scss

@@ -195,3 +195,10 @@ ul.menu li:first-child {
     font-size: 16px;
   }
 }
+
+// Hide tooltips on mobile
+@media (pointer:coarse) {
+  .tooltip::after {
+    display: none;
+  }
+}