SF-3127 Fix horizontal line appearing on home page

[josephmyers]

This fixes an issue where the background is shown just above/behind this element at some resolutions.

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This change is 

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.89%. Comparing base (de83faa) to head (7e2eb8d).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2947   +/-   ##
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  Coverage   80.89%   80.89%           
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  Files         533      533           
  Lines       31262    31262           
  Branches     5088     5066   -22     
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  Hits        25288    25288           
- Misses       5211     5223   +12     
+ Partials      763      751   -12     

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[Nateowami]

@josephmyers It took me a good minute or two of looking at this to figure out what this was even about. I thought the "book curve" was probably something about the border radius when selecting books for drafting.

In our CONTRIBUTING.md, there's a bullet point that says "Contextualize the change, even at the cost of being less specific."

A better title would be something like "Fix line appearing on home page"

In the past I've been able to reproduce this bug, but today I can't, so I can't really review this.

[RaymondLuong3]

I am not reproducing this bug either, but I can play around with it in dev tools and can see why this would fix the line. I'll approve and let you merge it after updating the title.

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @josephmyers)