Coy theme: Fix issue with defined height of the <pre> tag

* The max-height on the `<pre>` is if there is no defined height.

The definitions of the code ensure, that the contents stay inside the `<pre>`. The `width: 100%` is need if there is no defined height of the `<pre>`, see http://stackoverflow.com/questions/14262938/child-with-max-height-100-overflows-parent.