Preferred Text Scale/OS-level font scale w/ env() and meta

Summary: Features to reflect OS text size settings (e.g., Android/iOS accessibility settings) in web content. Previously, browsers other than Safari ignored OS settings to avoid layout breakage.

• env(preferred-text-scale): Exposes OS scale value as a CSS environment variable. Use for partial application.
• <meta name="text-scale" content="scale">: Applies OS settings to the entire page (opt-in). Implicitly equivalent to :root { font-size: calc(100% * env(preferred-text-scale, 1)); }.
• content="legacy": Maintains legacy behavior (ignores OS settings). Current default (2026/04/05) Default.

• Specs:
  • CSS Fonts Module Level 5 - text-scale meta
  • CSS Environment Variables Module Level 1 - text-zoom
• Explainers & Early Drafts:
  • Explainer: env(preferred-text-scale)
  • Explainer: meta tag for text scaling behavior
• Chrome Platform Status:
  • CSS env variable for OS-level font scale
  • meta name="text-scale"
• WPT:
  • N/A
• Intents:
  • Ship:
    • Intent to Ship: meta name="text-scale"
    • Intent to Ship: CSS env variable for OS-level font scale
  • Prototype:
    • Intent to Prototype: meta name="text-scale"
    • Intent to Prototype: CSS env variable for OS-level font scale
  • Experiment:
    • N/A
  • Ready for Developer Testing:
    • N/A
  • Unship:
    • N/A
  • Remove:
    • N/A
  • PSA:
    • N/A
• Standard Positions:
  • WebKit
    • Text-Scale <meta> element · Issue #587 · WebKit/standards-positions
  • Mozilla
    • Text-Scale <meta> element · Issue #1326 · mozilla/standards-positions
• Implementations:
  • Safari
    • N/A
  • Firefox
    • N/A
  • Chrome
    • env(preferred-text-scale) - Shipping in M138
    • meta name="text-scale" - Shipping in M139
• TAG Review:
  • env(preferred-text-scale) · Issue #1101 · w3ctag/design-reviews
  • <meta name="text-scale" content="scale" /> · Issue #1172 · w3ctag/gn-reviews
• Other Resources (Issues):
  • [css-env][css-values] UAs inconsistent in how OS font settings affect the default font-size `medium` · Issue #10674
  • [css-env][css-fonts-5] New <meta text-scale> tag to make UA initial font size respond to OS text scale setting · Issue #12380
  • Try text scaling support in Chrome Canary - Josh Tumath

Demos

• env(preferred-text-scale) - Apply text scaling to specific elements
• meta name="text-scale" - Apply text scaling to the entire page
• On macOS, launch Chrome Canary with: /Applications/Google\ Chrome\ Canary.app/Contents/MacOS/Google\ Chrome\ Canary \ --blink-settings=accessibilityFontScaleFactor=2.0 \ --enable-experimental-web-platform-features

Comparison of env(preferred-text-scale) and meta name="text-scale"

env	meta