Selector or pseudo-class · data last changed 10 Nov 2026
:child-combinator in email clients
Works in 16 of 21. Not supported in Outlook Classic and Proton Mail. Partial in Gmail Android and Gmail iOS. Untested in Superhuman.
Your reader in Outlook Classic sees the email without :child-combinator, even if it looks right where you tested it.
caniemail (MIT) via @emailens/engine 0.18.22
What to do instead in Outlook Classic
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.
There is no drop-in fix for :child-combinator in Outlook Classic. Design so the email still reads without it.
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:child-combinator is not among the 24 features we have screenshotted on real installs. The ones we have →
All 21 clients, problems first
| Client | Support |
|---|---|
| Outlook Classic | Not supported |
| Proton Mail | Not supported |
| Gmail Android | Partial See caveat 1 |
| Gmail iOS | Partial See caveat 1 |
| Superhuman | Untested |
Works in 16: Gmail, Outlook 365, Outlook (New) and 13 more. Show all
| Client | Support |
|---|---|
| Gmail | Works |
| Outlook 365 | Works |
| Outlook (New) | Works |
| Outlook iOS | Works |
| Outlook Android | Works |
| Outlook for Mac | Works |
| Apple Mail | Works |
| Apple Mail iOS | Works |
| Yahoo Mail | Works |
| Yahoo Mail Android | Works |
| Yahoo Mail iOS | Works |
| Samsung Mail | Works |
| Thunderbird | Works |
| HEY Mail | Works |
| AOL Mail | Works |
| Fastmail | Works |
Caveats (1)
- 1. Gmail Android, Gmail iOS: Partial. Not supported with non Google accounts.
Caveats as recorded by caniemail (MIT), one entry per wording.
How :child-combinator behaves
The child combinator (>) selects direct children of a parent. It is supported wherever <style> blocks survive, modern Apple Mail, Superhuman, and conditionally Gmail, and ignored where <style> is stripped. Compared to descendant combinators, the child combinator is more performant and more precise but equally limited in legacy clients.
- Outlook Classic 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.
Your next question
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