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Email rendering complianceReviewed September 7, 2026

What is Inline CSS?

Inline CSS places presentation declarations directly on an HTML element instead of relying only on a separate stylesheet or selector block.

Who this applies to#

  • Use inline declarations where a message needs essential element-level styling to travel with the HTML element

What Inline CSS requires#

  • Keep the underlying HTML order meaningful and use styles to improve presentation rather than supply missing content
HTML

The style attribute applies CSS declarations directly to an element

What this does not require#

  • Inline CSS does not make every CSS property or layout technique compatible with every email client

Common mistakes#

  1. Assuming inlining guarantees compatibility
  2. Duplicating conflicting declarations
  3. Using styles to encode essential text

Inline CSS checklist#

  • Keep semantic HTML
  • Inline critical presentation
  • Remove conflicts
  • Test priority clients

Commonly confused with#

Official sources#