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Does CSS vw unit Work in HTML Email?
Support for viewport width unit.
Quick Answer
Does vw unit work in HTML email?
The CSS vw unit property is supported in Gmail, Outlook (Mac / Web), Apple Mail, Yahoo! Mail, and others. It is NOT supported in Outlook (Windows), Fastmail. Always include a safe fallback for unsupported clients.
Which Email Clients Support CSS vw unit?
CSS support for vw 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 | ✓ Yes | ✓ Yes | — |
| Samsung Email | ? | ✓ Yes | — |
| Thunderbird | ✓ Yes | ? | — |
| ProtonMail | ✓ Yes | ✓ Yes | — |
| Fastmail | ✗ No | ? | — |
Notes
- #1 The HTML of the email message is embedded directly on the webmail (not in an <iframe>) and may not fill the full viewport's width. In this case, the vw values are relevant to the viewport (browser window) not the email message.
Frequently Asked Questions
Related CSS Properties
Test Your Email Now
Paste your HTML and see how it renders in clients that don't support vw unit.