Top/bottom grid lines missing

[monfera]

Describe the bug

The horizontal grid line for the bottom / zero Y intercept is missing, and sometimes, the topmost grid line is missing. I assume it's not intended, because there seems to be no need for omitting them; it looks a bit lopsided; the top one is sometimes present (see small multiples shot); and the leftmost/rightmost grid lines are not omitted either

To Reproduce Steps to reproduce the behavior:

1. Go to http://localhost:9001/?path=/story/small-multiples-alpha--grid-lines
2. Click on knobs to enable left/right axis grids
3. See that there's no grid line on the bottom

Expected behaviour Gridline for the Y=0 too

Screenshots

Version (please complete the following information):

• OS: OS X
• Browser: fresh chrome
• Elastic Charts: master as of morning of isssue creation date

Checklist

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• [ ] kibana cross issue tag is associated to the issue if any kibana cross issue is present

[nickofthyme]

AFAIR this is intentional https://github.com/elastic/elastic-charts/pull/1204

[markov00]

@monfera at the bottom, Y=0, there is already the Axis line so why do we need to display a grid line there?

[monfera]

Thanks, I'll do some thinking and possibly close it. Not sure if we should automatically elide the bottom grid line, and sometimes also the top gridline, as the original issue by @markov00 mentions the possibility for relying on the axis to simply overplot the bottom grid line, which sounds attractive, since the axis line is of higher priority than a grid line. A current workaround seems to be, style the axis line so it looks indistinguishable from a grid line