Updating cms.toolbar.modal scss to prevent greedy h2 display:none capture

When using plugins like django-form-designer, or writing my own plugins that use inline admin slots, the toolbar css, when a modal is displayed, attempts to hide the page title (default, the first h2 element under the #content div). Since the rule is written to hide any h2's under #content, the rule ends up being too greedy, and hiding form controls as seen below with the django-form-designer. This fix will allow only the title element to be targeted, achieving the modal effect while not hiding other elements.


![inlineadmin_before](https://cloud.githubusercontent.com/assets/486461/3345490/f6c0ec92-f8b8-11e3-8816-b018d32a6fd1.png)
![inlineadmin_after](https://cloud.githubusercontent.com/assets/486461/3345491/f98662f4-f8b8-11e3-9822-db65a682487a.png)