Emails that stay readable in dark mode

No more dark-gray-on-black surprises: every email Helios sends now adapts its colors to the recipient’s dark mode automatically, and the builder helps you catch hard-to-read color choices before you hit send.

• Automatic dark-mode adaptation: custom text, heading, and divider colors that would disappear on a dark background are brightness-adjusted (your hue stays intact) so the email is always legible. Sections with their own background keep their design untouched.
• Author the dark version yourself: flip the canvas to Dark mode and the inspector edits dark-only color variants. Auto shows what Helios derived; pick your own to override it, or reset back anytime.
• Contrast warnings: the inspector flags color combinations below the 4.5 readability guideline in both light and dark mode.

Full details in the email template builder guide.