Change the background color for the smooth slider over plots

[sroy3]

Following #3405 (comment)

Screen.Recording.2023-03-08.at.2.29.08.PM.mov

[codeclimate]

Code Climate has analyzed commit 9ac9506 and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (85% is the threshold).

This pull request will bring the total coverage in the repository to 95.7% (0.0% change).

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[mattseddon]

Up to you on whether or not to merge. Was a suggestion not a requirement.

[mattseddon]

Looks weird for zoomed-in plot 🤦🏻:

[sroy3]

Looks weird for zoomed-in plot 🤦🏻:

Now (first) vs before (second) the change:

Screen.Recording.2023-03-10.at.9.50.03.AM.mov

It looks like it's actually better most of the time. If we want to make it look better, we'd need something different completely. Let's leave it like this for now as it's an improvement, and change it when we think of something better.

[shcheklein]

I think the previous implementation was a bit better to be honest. I would try for these sliders to blend more with the plot itself. I don't see a strong reason for all sliders to have the same background, the context is different for them.

Sorry for going back and forth @sroy3 on this.

[sroy3]

I think the previous implementation was a bit better to be honest. I would try for these sliders to blend more with the plot itself. I don't see a strong reason for all sliders to have the same background, the context is different for them.

Sorry for going back and forth @sroy3 on this.

There are times when the slider is almost the same color as the background (see 0:42, 0:44, 0:48 in the video) (just making sure we're seeing the same thing). But I can easily revert and don't have an opinion on the matter.

[sroy3]

Reverted in #3444. Feel free to merge if needed.