Selector or pseudo-class · data last changed 10 Nov 2026
:adjacent-sibling 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 :adjacent-sibling, even if it looks right where you tested it.
caniemail (MIT) via @emailens/engine 0.18.22
What to do instead in Outlook Classic
Replicate the spacing relationships using explicit inline margin or padded cells for Outlook coverage. Treat adjacent-sibling styling as progressive enhancement.
There is no drop-in fix for :adjacent-sibling in Outlook Classic. Design so the email still reads without it.
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:adjacent-sibling 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 :adjacent-sibling behaves
The adjacent sibling combinator (+) selects an element that immediately follows another at the same level. It is supported in modern Apple Mail and webmail clients when <style> blocks survive, and ignored in Outlook for the usual reason. It is most useful for spacing relationships between adjacent content blocks.
- Outlook Classic ignores adjacent sibling selectors because <style> is stripped.
- Gmail rewrites class names, which can break adjacent-sibling selectors that rely on class matching.
- Apple Mail supports the combinator reliably in recent macOS and iOS releases.
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