CSS Properties

unit-initial

CSS property · 8 supported, 3 partial, 3 unsupported across 15 clients

Client Support

Client	Category	Engine	Support
Gmail	webmail	Gmail Web	Partial
Gmail Android	mobile	Gmail Mobile	Partial
Gmail iOS	mobile	Gmail Mobile	Partial
Outlook 365	webmail	Outlook Web	Supported
Outlook (New)	desktop	Outlook Web	Unsupported
Outlook Classic	desktop	Microsoft Word	Unsupported
Outlook iOS	mobile	Outlook Mobile	Supported
Outlook Android	mobile	Outlook Mobile	Supported
Apple Mail	desktop	WebKit	Supported
Apple Mail iOS	mobile	WebKit	Supported
Yahoo Mail	webmail	Yahoo	Unsupported
Samsung Mail	mobile	Samsung	Supported
Thunderbird	desktop	Gecko	Supported
HEY Mail	webmail	WebKit	Supported
Superhuman	desktop	Blink	Unknown

Client-by-client behaviour for unit-initial

Fully supports unit-initial (8): Outlook 365, Outlook iOS, Outlook Android, Apple Mail, Apple Mail iOS, Samsung Mail, Thunderbird, HEY Mail.

Partial support (3): Gmail, 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 (3): Outlook (New), Outlook Classic, Yahoo Mail. Plan fallbacks for these clients before relying on unit-initial in production sends.

Behaviour unverified in: Superhuman.