← CSS Support IndexDoes CSS
Does CSS inline-size Work in HTML Email?
Sets the width of an element in horizontal writing modes; equivalent to width in standard layouts.
Quick Answer
Does inline-size work in HTML email?
The CSS inline-size property is supported in Samsung Email, Thunderbird, ProtonMail. It is NOT supported in Gmail, Outlook (Windows), Outlook (Mac / Web), and others. Always include a safe fallback for unsupported clients.
Which Email Clients Support CSS inline-size ?
CSS support for inline-size across email clients
| Email Client | Desktop | Mobile / Web | Notes |
|---|---|---|---|
| Gmail | ✗ No | ✗ No | — |
| Outlook (Windows) | ✗ No | ? | — |
| Outlook (Mac / Web) | ✗ No | ✗ No | — |
| Apple Mail | ✗ No | ✗ No | — |
| Yahoo! Mail | ✗ No | ✗ No | — |
| Samsung Email | ? | ✓ Yes | — |
| Thunderbird | ✓ Yes | ? | — |
| ProtonMail | ✓ Yes | ✓ Yes | — |
| Fastmail | ✗ No | ? | — |
Frequently Asked Questions
Related CSS Properties
Test Your Email Now
Paste your HTML and see how it renders in clients that don't support inline-size .