Ordered list left-truncated in book.

[thepurpleblob]

To reproduce...

1. Create a new book activity
2. In the first 'chapter', simply create an ordered list with more than 10 lines
3. Save and display the chapter

When then numbers get beyond ten the first digit is not visible on the screen (i.e., it gets to 9 then appears to go to 0, 1, 2 etc.

[thepurpleblob]

Increasing the left-margin from 20px to 30px for ol and ul makes it better but I'm not sure that's a good solution (e.g. for very long lists)