Fix missing icons in Epub for definitions, examples, and collaborations

[profvjreddi]

In the Epub version of the textbook, icons for definitions, examples, and collaborations do not appear as expected. This issue seems to be related to foldbox.css and style files not properly handling the icon visibility or inclusion for these sections.

Steps to Reproduce

1. Generate or open the Epub version of the book.
2. Navigate to sections labelled as definitions, examples, or collaborations.
3. Observe that no icon is visible for these categories.

Expected Behavior

Icons should be displayed for definitions, examples, and collaborations in the Epub output.

Potential Causes

• Issues/missing rules in foldbox.css or related style files affecting Epub styling.
• Relevant selectors, font files, or image assets may not be referenced or included correctly during Epub build.

Suggested Fix

• Investigate foldbox.css and related style files for icon styling.
• Ensure any required assets (SVG, PNG, webfont, etc.) are available and properly exported for Epub.
• Test Epub output for sections with icons after adjusting style rules.

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Labels: ePub, bug
Issue Type: Bug