What it is
Inlining copies essential CSS declarations onto each element because some clients strip, scope, or incompletely support embedded styles.
Why it matters
A message that depends on one style block can degrade into unreadable content when the block is removed.
How to implement
Inline typography, spacing, colors, and table rules that are essential to comprehension. Use a build tool to inline consistently, then retain media queries and supported progressive rules in a style block.
Common mistakes
- Inlining before template rendering, leaving dynamic elements unstyled.
- Relying on shorthand properties with uneven support.
- Letting an inliner overwrite dark-mode or responsive declarations.
Verification
Inspect delivered HTML to confirm critical declarations are present. Remove all style blocks and confirm the message remains legible and actionable.
Sources
- CSS support in email clients — Can I Email