:child-combinator

Client-by-client behaviour for :child-combinator

Fully supports :child-combinator (10): Gmail, Outlook 365, Outlook iOS, Outlook Android, Apple Mail, Apple Mail iOS, Yahoo Mail, Samsung Mail, Thunderbird, HEY Mail.

Partial support (2): Gmail Android, Gmail iOS. Expect rendering quirks unique to each engine — partial support typically means a subset of values, an ignored shorthand, or sanitizer-specific rewrites.

No support (2): Outlook (New), Outlook Classic. Plan fallbacks for these clients before relying on :child-combinator in production sends.

Behaviour unverified in: Superhuman.

When to use :child-combinator in email

• Styling first-level navigation links without affecting nested submenus.
• Targeting top-level cards in a digest layout while leaving inner content untouched.
• Constraining responsive overrides to direct children only.

Rendering behaviour and edge cases

• Outlook on Windows ignores all selector-based styling because it strips <style> blocks.
• Apple Mail and modern Gmail honor the child combinator when <style> survives.
• Specificity matters — combine the child combinator with class names rather than tag selectors for predictable cascade order.

Recommended fallback strategy

Use the child combinator inside <style> blocks for clients that honor it, and inline the equivalent styles directly on the matching elements for Outlook compatibility.

Fixes & Workarounds