How do dark-mode render issues occur?

Dark mode issues occur because email clients handle color inversion inconsistently. Some fully invert light backgrounds to dark, some partially adjust, some ignore your colors entirely. Your carefully designed color palette meets algorithms that weren't built with your design in mind.

Common issues: Logo disasters-logos on white backgrounds get visible white rectangles when backgrounds invert. Invisible text-dark text on dark backgrounds after inversion. Unintended color shifts-a carefully chosen blue becomes an ugly cyan. CTA invisibility-buttons that blend into inverted backgrounds. Gradient breaks-gradients that looked smooth become harsh.

The issue is lack of standardization. There's no universal dark mode specification for email. Apple Mail, Gmail, Outlook, and others each implement their own logic. You can't prevent all issues; you can only design with defensive awareness and test across the clients your audience actually uses.