Package Structure · E-CSS

Risky CSS for Kindle layout

Your stylesheet references an external CSS resource or forces global text justification, which can create Kindle upload or layout problems.

Severity
warning

Automatic repair
Supported

Submission impact
KDP: warning

Rule ID
E-CSS

Error: Risky CSS for Kindle layout
Category: Package Structure
Severity: warning
Auto Repair: Supported
Rule ID: E-CSS
Affected: KDP=warning, Apple=warning, Google=pass, Kobo=pass

Check this automatically with Cermify

Why this happens

@import or url() pointing at http(s) stylesheets outside the EPUB.
Global * or body { text-align: justify } that fights Kindle user settings.
Fixed px layouts that break reflow on small screens.
Vendor-only CSS that Kindle strips or mishandles.

How platforms treat it

Platform	Result
KDP	warning
Apple Books	warning
Google Play	pass
Kobo	pass

How Cermify detects it

Scan CSS and style attributes for external @import / remote url().
Detect aggressive global justification and other known Kindle-risk patterns.
Record stylesheet path and rule excerpt.
Classify as warning unless paired with hard validity failures (then see E-RSC005).

Automatic repair

Cermify can inline or drop remote imports when a local copy exists, and soften global justify rules. Layout-sensitive design CSS is not fully rewritten automatically.

Manual fix

Bundle all stylesheets inside the EPUB and declare them in the manifest.
Replace remote @import with local files.
Avoid forcing full-book justification; let the reading system handle alignment when possible.
Preview on Kindle Previewer with several font sizes.

Examples

Keep CSS inside the package; avoid global justify locks.

Incorrect

@import url("https://cdn.example.com/book.css");
body { text-align: justify !important; }

Correct

@import url("../styles/book.css");
p.body { /* optional local class; avoid global !important justify */ }

FAQ

Is justify always wrong?

Not always on specific classes, but global forced justify often conflicts with Kindle user preferences and is flagged as risky.

Can I use Google Fonts CSS URLs?

No for KDP EPUB—remote CSS/fonts are unreliable offline and may fail checks. Embed licensed font files instead (see E-FONT).