Dual Screen UX Lab

Simulate dual-display phone ergonomics, seam occlusion, posture continuity, and multi-window app layouts with production-ready CSS spanning queries.

Layout & Postures

App Layout Preset Preconfigured dual-screen layout pattern

Hinge Posture

Panel Ratio

Seam Gap (12px)

Fold Orientation

Ergonomics & Safety

Show One-Hand Thumb Reach Heatmap Overlays thumb arc comfortable zones vs stretch zones

Active Hinge Collision Detection Warns if actionable UI elements cross the hinge dead zone

System ready. Hinge collision audit: 0 issues.

Total Viewport 572 x 390 px

Hinge Deadzone 12 px (0.3 cm)

Active Posture Extended Flat

Hinge Occlusion 0 Violations

Inbox / Feed Screen 1

SEAM OCCLUSION

Article Detail Screen 2

/* CSS Spanning Query will appear here */

The Dual-Screen Software Gamble: Why UX Fails at the Seam

When dual-screen or foldable smartphones launch, standard single-viewport mobile apps face severe ergonomic degradation. If software treats two hinged displays as a single continuous canvas without seam awareness, critical UI components (submit buttons, modal dismiss targets, text columns) get swallowed or bifurcated by the central bezel gap.

This laboratory models the standard W3C screen-spanning CSS media feature and the Dual-Screen fold geometry APIs, ensuring interfaces automatically reflow into Master-Detail, Companion Deck, or Flex posture layouts.

W3C Screen-Spanning Architecture

Modern foldable operating systems expose fold coordinates through CSS environment variables:

env(fold-left) & env(fold-top) — Starting coordinate of the hinge
env(fold-width) & env(fold-height) — Dimensional thickness of the physical seam
@media (screen-spanning: single-fold-vertical) — Triggers side-by-side app pairing
@media (screen-spanning: single-fold-horizontal) — Triggers top-viewer bottom-keyboard posture