Border of Title is Against the Edge of the Screen

[mchowning]

Describe the bug
Border around title when selected is against the edge of the screen

To Reproduce
Steps to reproduce the behavior:

1. Go to a post and select the title
2. Observe that the border is against the edge of the screen

Expected behavior
The border should not be against the edge of the screen.

Screenshots

Smartphone (please complete the following information):

• Device: Pixel, iPhone Xr
• OS: Android X, iOS 13.4.1
• 4beb166

Additional context
It appears this regression was introduced since the 1.27 release.

[mchowning]

Per @iamthomasbishop on Slack:

Depending on if the border is on inside or outside, it would either be 3px or 4px margin on left/right of the block border 1nd 12px or 13px padding on the inside of the border (on left/right). So the text should line up to the 16px key line. 3px margin, 1px border, 12px padding...IIRC

Related to #2021