To optimize grid scrolling performance, we can upgrade CSS containment for component-based columns from contain: layout paint style to contain: strict.
This allows the browser to completely skip layout and style recalculations for these components during scroll, treating them as rigid boxes.

Targets:

1. GitHubOrgs: Add width: 100% and upgrade to strict.
2. Heuristics (Impact): Add width: 100% and upgrade to strict.
3. CountryFlag: Add height: 100% and upgrade to strict.

Note: Sparkline (Activity) already uses contain: strict. IconLink will remain as-is to preserve flexibility in non-grid contexts.