mobile-principles

Mobile Principles

Touch-first UX context. Loaded when mobile is detected (web mobile, iOS, Android). Concise rules here. Deep-dive in references/.

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Touch Targets

Platform	Minimum	Recommended	Spec
Apple iOS	44pt	44pt + 8pt spacing	Apple HIG
Android	48dp	48dp + 8dp spacing	Material Design
Web mobile	44px	44px + 8px spacing	WCAG 2.5.5

Rule of thumb: any tap target smaller than the platform minimum is a usability bug, period. The hit area can extend beyond the visible glyph (use padding, hitSlop, or a transparent inner spacer), but the interactive surface must reach the minimum. Spacing matters as much as size: two 44pt buttons touching edges are still mistappable.

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No-Hover Doctrine

:hover does not exist on touch. Treating it as a primary trigger means hidden affordances on every phone. Anything reachable only by hover is, on mobile, simply gone. Visible-by-default is the rule; hover styles are a desktop enhancement, never a load-bearing interaction.

CSS - gate hover styles behind a media query:

.card { opacity: 1; transform: translateY(0); }

@media (hover: hover) and (pointer: fine) {
  .card { opacity: 0.85; }
  .card:hover { opacity: 1; transform: translateY(-2px); }
}

SwiftUI - tap and long-press, no pseudo-hover:

Image(systemName: "heart")
  .onTapGesture { toggleLike() }
  .contextMenu {
    Button("Share", systemImage: "square.and.arrow.up", action: share)
    Button("Report", systemImage: "flag", role: .destructive, action: report)
  }

Compose - combinedClickable for tap + long-press:

Box(
  modifier = Modifier
    .combinedClickable(
      onClick = { toggleLike() },
      onLongClick = { showContextMenu() },
    )
) {
  Icon(Icons.Default.Favorite, contentDescription = "Like")
}

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Thumb Zones (Hoober)

Steven Hoober's research shows portrait phone use is overwhelmingly one-handed or cradled, with the thumb pivoting from the bottom corner. The screen splits into reachable zones: