Gmail vs Gmail iOS: CSS Support Differences
Gmail renders with Gmail Web; Gmail iOS renders with Gmail Mobile. The gap runs almost entirely one way: 4 features work in Gmail and break in the other, against 0 in the reverse direction. Build for the stricter one and the permissive one follows.
Support data derived from caniemail.com (MIT) - last synced Sep 2, 2026 - engine data v0.12.2
106
work in both
the safe intersection
4
only in Gmail
breaks in Gmail iOS
0
only in Gmail iOS
breaks in Gmail
60
partial on one side
renders, with caveats
Works in Gmail, breaks in Gmail iOS
Each of these needs a fallback if the send reaches both.
Works in Gmail iOS, breaks in Gmail
Nothing: every feature Gmail iOS supports is also supported in Gmail.
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.
- <base>
- <body>
- <button type="reset">
- <button type="submit">
- <form>
- <input type="reset">
- <input type="submit">
- <select>
- <strike>
- <style>
- <ul>
- [background]
- @media
- !important
- background-blend-mode
- background-clip
- background-origin
- background-size
- box-shadow
- calc
- clamp
- display
- fit-content
- float
- font-size-adjust
- gap
- html5-semantics
- list-style
- margin
- max
- min
- mix-blend-mode
- object-fit
- object-position
- overflow
- rgb
- rgba
- text-decoration
- text-decoration-color
- text-indent
- text-justify
- text-overflow
- text-underline-position
- unit-initial
- white-space
- word-break
- writing-mode
- :adjacent-sibling
- :attribute-selector
- :chaining
- :child-combinator
- :class-selector
- :descendant-combinator
- :general-sibling
- :grouping
- :id-selector
- :type-selector
- :universal-selector
- display:flex
- display:grid
A further 128 features render in neither client. Not a difference between them, but the other half of the answer to what you can actually use, so the four counts above deliberately do not sum to 298.
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 30
- HTML Elements 12
- Pseudo-Classes & Selectors 12
- CSS Functions 5
- CSS At-Rules 2
- HTML & Email Structure 2
12 of these already have a fix
Each links to a copy-paste snippet that keeps the feature working in Gmail iOS without dropping it in Gmail.
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Questions
- How different are Gmail and Gmail iOS?
- They disagree on 64 of the 298 features verified in both clients, or 21%. 106 features render in both and are the safe intersection to build on.
- What works in Gmail but not Gmail iOS?
- 4 features, including <wbr>, @media orientation, anchor-links, :hover. Each needs a fallback if the send reaches both clients.
- Which engines are these two clients using?
- Gmail renders with Gmail Web; Gmail iOS renders with Gmail Mobile. 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.
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