Dark Mode Email Signature

A dark mode email signature is one designed to render correctly when the recipient's email client is set to dark mode. Email clients handle dark mode differently. Apple Mail (macOS and iOS) automatically inverts colors of light backgrounds in HTML email, which can render dark text on dark backgrounds in unintended ways. Outlook desktop applies its own dark-mode inversion. Gmail (web and mobile) supports the `prefers-color-scheme: dark` CSS media query in HTML email, allowing signatures to provide explicit dark-mode variants. Best practices include using PNG or SVG logos with transparent backgrounds so they work on either light or dark backgrounds, avoiding hard-coded background colors on signature blocks (which conflict with inversions), using CSS media queries to provide dark-mode-specific overrides where supported, and testing the signature in both light and dark modes across major clients. Some signature platforms emit two image variants (light and dark) and use CSS to swap between them, which works in clients supporting `prefers-color-scheme`.