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Does CSS rem unit Work in HTML Email?
Support for rem unit, relative to the root font-size.
Quick Answer
Does rem unit work in HTML email?
The CSS rem unit property is supported in Gmail, Outlook (Mac / Web), Apple Mail, Samsung Email, and others. It is NOT supported in Outlook (Windows), Yahoo! Mail. Always include a safe fallback for unsupported clients.
Which Email Clients Support CSS rem unit?
CSS support for rem unit across email clients
| Email Client | Desktop | Mobile / Web | Notes |
|---|---|---|---|
| Gmail | ✓ Yes | ✓ Yes | — |
| Outlook (Windows) | ✗ No | ? | — |
| Outlook (Mac / Web) | ✓ Yes | ✓ Yes | — |
| Apple Mail | ✓ Yes | ✓ Yes | — |
| Yahoo! Mail | ✗ No | ✗ No | — |
| Samsung Email | ? | ✓ Yes | — |
| Thunderbird | ✓ Yes | ? | — |
| ProtonMail | ✓ Yes | ✓ Yes | — |
| Fastmail | ✓ Yes | ? | — |
Frequently Asked Questions
Related CSS Properties
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