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 your email colors in unexpected ways. Some email clients automatically invert or adjust colors. This can make bright or saturated colors appear very different from your original design.
Knak helps identify potential Dark Mode issues while you build. The Optimize tab displays warnings when strong colors or strong color combinations may create readability problems.
How Dark Mode Changes Colors
Some email clients support Dark Mode editing. Others simulate Dark Mode by transforming your light-mode design.
For example:
Outlook 365 inverts colors automatically
Gmail apps may darken or lighten backgrounds
Bright colors can become muted or muddy
Dark colors can become lighter
Strong colors are the most likely to shift unexpectedly.
Example of Color Changes in Dark Mode
View Dark Mode Warnings in Knak
Knak warns you when your design may have Dark Mode readability issues.
For example:
Bright text on a saturated background
Neon colors paired together
High-contrast vivid combinations
Knak warns you when strong color combinations may create readability problems.
Find Warnings in the Optimize Tab
Open your email in Knak
Click the Optimize tab
Review any Dark Mode warnings
Warnings appear when:
You use highly saturated colors
You combine multiple strong colors
Text contrast may become difficult to read
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.
Strong Colors in Dark Mode
Strong colors often change the most in Dark Mode.
Examples include:
Bright yellow
Neon green
Saturated red
Vivid purple
These colors may:
Become lighter
Shift to another hue
Lose contrast
Reduce readability
Improve Strong Colors
Try these adjustments:
Use more muted tones
Add more white to lighten colors softly
Add more black to reduce saturation
Avoid neon or highly vivid colors
Test multiple shades before publishing
Muted and neutral colors usually remain more stable in Dark Mode.
Use a More Neutral Text Color
Neutral text colors usually display more consistently in Dark Mode.
Example - A bright yellow-green text color on a dark purple background may:
Become darker
Lose readability
Shift into muddy tones
Changing the text closer to white often improves visibility.
Even when a color combination meets Web Content Accessibility Guidelines (WCAG) contrast requirements in light mode, Dark Mode transformations can still reduce readability in some email clients.
Best Practices for Text Colors
Use:
White
Off-white
Light gray
Muted pastel tones
Avoid:
Highly saturated text colors
You should still test your emails in Dark Mode, even when your colors are WCAG compliant in light mode.
Use a More Neutral Background Color
If text adjustments do not help, modify the background color instead.
Example: A dark saturated background may become too dark in Gmail Dark Mode. This can reduce text contrast.
Lightening the background often improves readability.
Best Practices for 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.