CSS Functions

min

CSS function · 7 supported, 3 partial, 10 unsupported across 21 clients

The min() CSS function returns the smallest of a set of values and is used to cap a property at a maximum. Modern Apple Mail and webmail clients support it; Outlook on Windows ignores it. Like calc() and clamp(), min() is best treated as a progressive enhancement with a literal fallback.

Client Support

Client	Category	Engine	Support
Gmail	webmail	Gmail Web	Supported
Gmail Android	mobile	Gmail Mobile	Partial
Gmail iOS	mobile	Gmail Mobile	Partial
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	Unsupported
Outlook for Mac	desktop	WebKit	Supported
Apple Mail	desktop	WebKit	Supported
Apple Mail iOS	mobile	WebKit	Supported
Yahoo Mail	webmail	Yahoo	Unsupported
Yahoo Mail Android	mobile	Yahoo	Unsupported
Yahoo Mail iOS	mobile	Yahoo	Unsupported
Samsung Mail	mobile	Samsung	Partial
Thunderbird	desktop	Gecko	Supported
HEY Mail	webmail	WebKit	Supported
Proton Mail	webmail	Proton	Supported
AOL Mail	webmail	AOL	Unsupported
Fastmail	webmail	Fastmail	Unsupported
Superhuman	desktop	Blink	Unknown

Client-by-client behaviour for min

Fully supports min (7): Gmail, Outlook for Mac, Apple Mail, Apple Mail iOS, Thunderbird, HEY Mail, Proton Mail.

Partial support (3): Gmail Android, Gmail iOS, Samsung 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 (10): Outlook 365, Outlook (New), Outlook Classic, Outlook iOS, Outlook Android, Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, AOL Mail, Fastmail. Plan fallbacks for these clients before relying on min in production sends.

Behaviour unverified in: Superhuman.

When to use min in email

Preventing a fluid container from exceeding a maximum width.
Capping responsive font-size at a maximum readable size.
Limiting padding in narrow viewports while allowing larger spacing on wider screens.

Rendering behaviour and edge cases

Outlook on Windows ignores min() entirely.
Apple Mail supports min() reliably in recent macOS and iOS releases.
Gmail Web's support varies between mobile and desktop builds.

Recommended fallback strategy

Provide a literal fallback value before any min() declaration. Reserve min() for refinements where the absence of clamping is non-critical.