UV version
v4.1.0

Issue Summary
When viewing a PDF file in Universal Viewer (UV), the Zoom In and Zoom Out buttons are missing labels. Users can see them, but there’s no text to indicate what they do.

Steps to Reproduce

• Open Universal Viewer in any browser.
• Load a PDF document.
• Click the Zoom In and Zoom Out buttons, observed that they are missing labels.

Expected Behaviour

• The Zoom In and Zoom Out buttons should have clear labels.
• The Zoom In and Zoom Out labels should be consistent across all material formats (PDF, images, text, etc.).