Selector or pseudo-class · data last changed 10 Nov 2026
:descendant-combinator in email clients
Works in 17 of 21. Not supported in Proton Mail. Partial in Gmail Android and Gmail iOS. Untested in Superhuman.
Your reader in Proton Mail sees the email without :descendant-combinator, even if it looks right where you tested it.
caniemail (MIT) via @emailens/engine 0.18.22
What to do instead in Proton Mail
Inline the equivalent styles on the targeted elements for Outlook coverage. Reserve descendant selectors in <style> for progressive enhancement on clients that preserve <style> blocks.
There is no drop-in fix for :descendant-combinator in Proton Mail. Design so the email still reads without it.
No signup · Five clients free, Outlook Classic included · All 21 with an account
The checker needs a computer screen.
Proton Mail opens with a free account. Create a free account →
:descendant-combinator is not among the 24 features we have screenshotted on real installs. The ones we have →
All 21 clients, problems first
| Client | Support |
|---|---|
| Proton Mail | Not supported |
| Gmail Android | Partial See caveat 1 |
| Gmail iOS | Partial See caveat 1 |
| Superhuman | Untested |
Works in 17: Gmail, Outlook 365, Outlook (New) and 14 more. Show all
| Client | Support |
|---|---|
| Gmail | Works |
| Outlook 365 | Works |
| Outlook (New) | Works |
| Outlook Classic | 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 :descendant-combinator behaves
The descendant combinator (a single space between selectors) matches any descendant element, regardless of nesting depth. It is the most common selector pattern in CSS but in email, like all selector-based styling, only works when the client preserves <style> blocks. Outlook Classic strips <style>, so descendant selectors never apply there.
- Specificity-collision risk, descendant selectors easily over-apply when classes overlap.
- Outlook ignores descendant selectors because <style> is stripped.
- Gmail's class-rewriting can break descendant selectors that depend on class names.
Your next question
- Does :class-selector work in Proton Mail?
Works in 17 of 21 · partial in 2 · not supported in 1 · 1 untested
- Does :grouping work in Proton Mail?
Works in 17 of 21 · partial in 2 · not supported in 1 · 1 untested
- Does :id-selector work in Proton Mail?
Works in 17 of 21 · partial in 2 · not supported in 1 · 1 untested
- Does :type-selector work in Proton Mail?
Works in 17 of 21 · partial in 2 · not supported in 1 · 1 untested
- Does :adjacent-sibling work in Proton Mail?
Works in 16 of 21 · partial in 2 · not supported in 2 · 1 untested
- Does :child-combinator work in Proton Mail?
Works in 16 of 21 · partial in 2 · not supported in 2 · 1 untested
Every feature in Proton Mail · All email CSS features · What real installs show
Paste your email
Get new email CSS fixes by email.