CSS Properties

light-dark

CSS property · 3 supported, 3 partial, 11 unsupported across 21 clients

As of Sep 2, 2026, light-dark fails or degrades in 18 of 21 email clients, treat it as progressive enhancement, never structure.

0/7 webmail, 2/6 desktop, 1/8 mobile clients support light-dark fully.
Unsupported in Gmail, Gmail Android, Gmail iOS, Outlook 365 and 7 more.
Partial in Samsung Mail, HEY Mail, Proton Mail, behavior differs from browsers, test before relying on it.
Outlook Classic (Word engine, supported to at least 2029) does not fully support light-dark, and its replacement changes little here; see the deprecation diff.
Across all clients, only 6 of 298 tracked HTML/CSS features render identically everywhere.

Source: caniemail.com (MIT), via the Emailens engine. Last tested upstream Aug 14, 2024, synced by Emailens Sep 2, 2026.

Client Support

Client	Category	Engine	Support
Gmail	webmail	Gmail Web	Unsupported
Gmail Android	mobile	Gmail Mobile	Unsupported
Gmail iOS	mobile	Gmail Mobile	Unsupported
Outlook 365	webmail	Outlook Web	Unsupported
Outlook (New)	desktop	Outlook Web	Unsupported
Outlook Classic	desktop	Microsoft Word	Unsupported
Outlook iOS	mobile	Outlook Mobile	Unsupported
Outlook Android	mobile	Outlook Mobile	Unknown
Outlook for Mac	desktop	WebKit	Unsupported
Apple Mail	desktop	WebKit	Supported^{See caveat 1}
Apple Mail iOS	mobile	WebKit	Supported
Yahoo Mail	webmail	Yahoo	Unsupported
Yahoo Mail Android	mobile	Yahoo	Unknown
Yahoo Mail iOS	mobile	Yahoo	Unsupported
Samsung Mail	mobile	Samsung	Partial^{See caveat 2}
Thunderbird	desktop	Gecko	Supported
HEY Mail	webmail	WebKit	Partial^{See caveat 3}
Proton Mail	webmail	Proton	Partial^{See caveat 3}
AOL Mail	webmail	AOL	Unsupported
Fastmail	webmail	Fastmail	Unknown
Superhuman	desktop	Blink	Unknown

Documented caveats (3)

1.Apple Mail: Only supported if you’ve updated your OS with Safari 17.5 or later.
2.Samsung Mail: Partial. Not supported with Hotmail/Outlook accounts.
3.HEY Mail, Proton Mail: Buggy. The function is supported but the color stays light even in dark mode.

Caveats recorded by caniemail.com (MIT) and carried verbatim, one entry per wording rather than per client.

Client-by-client behaviour for light-dark

Fully supports light-dark (3): Apple Mail, Apple Mail iOS, Thunderbird.

Partial support (3): Samsung Mail, HEY Mail, Proton Mail. Expect rendering quirks unique to each engine. Partial support typically means a subset of values, an ignored shorthand, or sanitizer-specific rewrites.

No support (11): Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook (New), Outlook Classic, Outlook iOS, Outlook for Mac, Yahoo Mail, Yahoo Mail iOS, AOL Mail. Plan fallbacks for these clients before relying on light-dark in production sends.

Behaviour unverified in: Outlook Android, Yahoo Mail Android, Fastmail, Superhuman.