How many email clients support ?

It works in 16 of 21, partial in 5.

Does work in Gmail iOS?

is partly supported in Gmail iOS. Closest to Gmail: Gmail iOS, which agrees on 251 of the 300 features both are tested on.

<style> in Gmail

Partial <style> is partly supported in Gmail.

Not supported inside the <body>.

Works in 16 of 21 · partial in 5

Which clients

Works: Outlook 365, Outlook (New), Outlook iOS, Outlook Android, Outlook for Mac, Apple Mail, Apple Mail iOS, Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, Samsung Mail, Thunderbird, HEY Mail, AOL Mail, Fastmail, Superhuman
Partial: Gmail, Gmail Android, Gmail iOS, Outlook Classic, Proton Mail

Your reader in Gmail may not see <style> the way you wrote it, even if it looks right where you tested it.

What to do instead in Gmail

Inline CSS for Gmail compatibility

instead

6 lines

<div style="background-color: #6d28d9; padding: 32px;">
  <h1 style="color: #fff; font-size: 24px;
             font-family: Arial, sans-serif; margin: 0;">
    Hello
  </h1>
</div>

Show the original

before

7 lines

<style>
  .header { background-color: #6d28d9; padding: 32px; }
  .title  { color: #fff; font-size: 24px; }
</style>
<div class="header">
  <h1 class="title">Hello</h1>
</div>

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What Gmail does with <style>

caniemail record, tested upstream 27 Jul 2023

Partial. Not supported inside the <body>.
The size of the <style> tag is limited to 16 KB

Your next question

Every feature in Gmail · <style> in every client

Questions

How many email clients support <style>?: It works in 16 of 21, partial in 5.
What do I use instead of <style> in Gmail?: Inline CSS for Gmail compatibility.
Does <style> work in Gmail iOS?: <style> is partly supported in Gmail iOS. Closest to Gmail: Gmail iOS, which agrees on 251 of the 300 features both are tested on.

To see what else in your email Gmail does not support, paste the whole email.

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caniemail (MIT) via @emailens/engine 0.18.22 · tested upstream 27 Jul 2023 · data last changed 10 Nov 2026 · Outlook (New) cells are the engine's mapping