Apple Mail vs Apple Mail iOS: CSS Support Differences

Works in Apple Mail, breaks in Apple Mail iOS

Each of these needs a fallback if the send reaches both.

• meta-color-scheme
• :focus

Works in Apple Mail iOS, breaks in Apple Mail

Nothing: every feature Apple Mail iOS supports is also supported in Apple Mail.

Partial on one side

These render in both, but one client applies caveats the other does not. They fail quietly, which makes them the expensive ones.

• <object>
• <picture>
• <select>
• <svg>
• <video>
• [target]
• @media orientation
• cursor
• nesting
• overflow
• overflow-wrap
• position
• pseudo-class-active
• resize
• text-underline-position
• unit-vh
• user-select
• word-break

Where the divergence sits

Two pairs with the same headline number can be different problems. For these two it concentrates in CSS Properties.

• CSS Properties 10
• HTML Elements 5
• Pseudo-Classes & Selectors 2
• HTML & Email Structure 1
• HTML Attributes 1
• CSS At-Rules 1

6 of these already have a fix

Each links to a copy-paste snippet that keeps the feature working in Apple Mail iOS without dropping it in Apple Mail.

• <svg>
• <video>
• overflow
• overflow-wrap
• position
• word-break

Check your own HTML against both

Questions

How different are Apple Mail and Apple Mail iOS?

They disagree on 20 of the 296 features verified in both clients, or 7%. 270 features render in both and are the safe intersection to build on.

What works in Apple Mail but not Apple Mail iOS?

2 features, including meta-color-scheme, :focus. Each needs a fallback if the send reaches both clients.

Which engines are these two clients using?

Apple Mail renders with WebKit; Apple Mail iOS renders with WebKit. Where two clients share an engine the divergence is usually configuration, and where they do not it is the engine itself.

Is this measured in the real clients?

No. These are documented support levels derived from caniemail.com (MIT-licensed), carried in @emailens/engine data version 0.12.2 and last synced Sep 2, 2026. That sync date is not a test date: caniemail's own per-feature tests run from Feb 28, 2019 to Jul 13, 2026. Anything described as a transform is applied per those documented rules rather than captured from a real client.