Description

The combo box list doesn't have a high enough z-index to overlap other positioned element such as the buttons for another combo box it could be placed above.

The z-index should be increased to make sure it covers non dialog items.

<img width="459" alt="Screenshot 2020-08-03 09 58 02" src="https://user-images.githubusercontent.com/1385752/89196565-01b64f80-d570-11ea-81e8-1

Describe the bug
On the new registration page, the nickname prefix moves to a separate line.

To Reproduce
Steps to reproduce the behavior:

1. Go to '/users/sign_up'
2. Resize viewport
3. See the nickname input wrapping to a new line

Expected behavior
Prefix and input stay on the same line

Screenshoot
![big_nickname_wrap](https://user-images.githubusercontent.com/691

Minor recommendation:

Screen readers announce the word 'content' in the 'Skip to content' bypass block in the context of 'feeling content' the inflection is different to the intended meaning of 'the word.

Adding the word 'main' into the mix fixes the pronunciation 'Skip to main content' is vocalized in the correct pronunciation.

Pedantic; I know :-)

Ensure new starter can create new component by following the step by step guide. Consult GG for clarification if necessary.