UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.167 Safari/537.36

Steps to reproduce the problem:
1. Open styles panel
2. Write a style name with space(like: "background color")
3. The style become undeletable, uneditable and so on.

What is the expected behavior?
Warning message

What went wrong?
See steps to reproduce. It should be clear to understand

Did this work before? N/A 

Chrome version: 64.0.3282.167  Channel: stable
OS Version: OS X 10.13.3
Flash Version: 

I(my girlfriend) have found a bug!) Yuppy)