For `.underlay .notice`:
* How about removing height? It creates empty space in the dialog, and even without it, the dialog is reasonably centered.
* Setting `font-family: "Helvetica Neue",Arial,sans-serif;` allows you to remove subsequent font-family declarations and adds a fallback for Windows.
* Setting `color: #4D4E53` allows you to remove subsequent color declarations and follows the style guide.

For `.underlay .notice h1`:
* Set `margin: 16px 16px 0;` to give it the same margin as the main text.

For `.underlay .notice h2`:
* Setting `background-color: #FFCD36;` makes the modal seem more like an alert and will grab more attention. This yellow is also from style guide.