Bug - Mobile view allows horizontal scrolling

# Background
The svg used as a target on the venn diagram controls extends too far right and beyond the viewport. This allows horizontal scrolling.

On desktop, this isn't a problem, but on mobile, it's too easy to accidentally scroll horizontally, which looks sloppy.

# 🎯 Goal - Do not allow horizontal scrolling on mobile

Reproduce the issue in a mobile-sized viewport, then locate the Venn diagram SVG target mentioned in the report and inspect how it extends beyond the viewport. Confirm the fix by checking that the mobile view no longer permits horizontal scrolling while the diagram remains usable.

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