Test several desktop stages
Use 1280 and 1440px for laptops, 1920px for mainstream desktops, and 2560 or 3840px to expose ultra-wide issues. A 4K panel may expose a smaller CSS viewport when system scaling is enabled.
Control reading width
Articles and forms benefit from a sensible max-width. Dashboards can add columns, but should not stretch a single text line across the whole display.
Review high-density assets
- Serve appropriately sized photos
- Use reliable vector or multi-density icons
- Account for DPR in canvas charts
- Cap video and background asset sizes
Include zoom and display scaling
Test 100%, 125%, 150% and 200% scaling. This catches overflow and density problems that a single full-width 4K frame misses.