This information mostly applies to email clients that do not support Dark Mode editing. Email clients that support Dark Mode editing give you more control over how your email appears in Dark Mode. Learn more in the Dark Mode Editing article.
Overview
Dark Mode can change email colors in unexpected ways. Some email clients automatically invert or adjust colors instead of using your original design settings.
This can cause:
Bright colors to appear muted
Dark colors to become lighter
Text contrast to decrease
Readability issues in certain email clients
Strong or highly saturated colors are the most likely to shift unexpectedly.
Knak helps identify potential Dark Mode readability issues while you build.
The Optimize tab displays warnings when color combinations may become difficult to read in Dark Mode.
How Dark Mode Changes Colors
Some email clients support Dark Mode editing. Others simulate Dark Mode by automatically transforming your Light Mode design.
For example:
Outlook 365 may invert colors automatically
Gmail apps may darken or lighten backgrounds
Bright colors may become muddy
Strong contrast combinations may lose readability
Different email clients process Dark Mode differently.
Example of Color Changes in Dark Mode
View Dark Mode Warnings in Knak
Knak warns you when your design may have readability issues in Dark Mode.
Warnings may appear when:
You use highly saturated colors
You combine multiple strong colors
Text contrast may become difficult to read
Find Warnings in the Optimize Tab
Open your email in Knak.
Click the Optimize tab.
Review any Dark Mode warnings.
Edit Problem Colors
Click Edit beside the warning
Update the affected color settings
Preview your email again in Dark Mode
Knak takes you directly to the affected section.
Recommended Color Practices
Neutral and muted colors usually display more consistently in Dark Mode.
Improve Text Readability
Using more neutral text colors can improve visibility across email clients.
Recommended Text Colors
Use:
White
Off-white
Light gray
Muted pastel tones
Avoid:
Highly saturated text colors
Neon colors
Extremely vivid color combinations
For example, bright yellow-green text on a dark purple background may:
Become darker
Lose readability
Appear muddy or distorted
Even when a color combination meets Web Content Accessibility Guidelines (WCAG) contrast requirements in Light Mode, Dark Mode transformations can still reduce readability.
Adjust Background Colors When Needed
If text adjustments do not improve readability, update the background color instead.
Dark saturated backgrounds may become even darker in some email clients, including Gmail Dark Mode. This can reduce text contrast. Lightening the background often improves readability.
Recommended Background Colors
Use:
Soft neutral backgrounds
Muted brand colors
Moderately saturated colors
Avoid:
Extremely dark saturated backgrounds
Neon backgrounds
High-intensity color fills
Test Emails in Dark Mode
Always test your email before sending.
Test across:
Outlook 365
Gmail App for Android
Apple Mail
Outlook Mobile
Gmail Web
Different clients process Dark Mode differently.
Tip: Check out Knak’s Email Testing feature to preview your email across multiple email clients before sending. This helps you identify Dark Mode rendering issues early.
Need more help? Contact support via live chat using the chat bubble in the bottom right corner or email support@knak.com.