Khan Academy exercises - Missing x-axis labels

[pcenov]

Observed behavior

This issue was initially reported here: https://community.learningequality.org/t/display-issues-with-khan-academy-exercises/2425/1
Note that I am currently able to replicate only the issue with the missing x-axis labels, the numeric input is functioning correctly.

Steps to reproduce the issue

1. Install Kolibri 0.15.2
2. Import Khan Academy's (English - US curriculum) > Math by grade > 3rd grade > Represent and interpret data > Picture graphs
3. Create a quiz for 'Read picture graphs (multi-step problems)'
4. Interact with the quiz

Expected result

Fully visible x-axis labels

Screenshots

Issue	Screenshot
Khan Academy's site
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Coach view
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Learner view
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Usage Details

Ubuntu 20 - Chrome, Firefox

[pcenov]

@radinamatic

[rtibbles]

Fixed in #9446