Dark mode - transparent background not working in native Apple iOS mail app?

Hey there @DavidSandel,

Dark mode changes are done once the email is already compressed and sent out of Klaviyo, so the changes stem from the email client, rather than Klaviyo. There are multiple devices and email apps that handle Dark Theme on the HTML side differently. Some email clients will invert colors, while others will simply change all colors darker. At this time, since the changes occur once the email is already sent out, there aren’t too many options within Klaviyo to alleviate dark mode rendering difficulties. 
Please take a look here, at our Dark Mode Best Practices help doc.

We do indeed recommend using transparent backgrounds on images (rather than white backgrounds, for example), including logos.
As well as, using live text rather than images with text on it, to ensure your message comes through on dark mode. Example:



We understand dark mode can be frustrating as there is not much control around the way your email displays in a recipient's inbox. It's important to keep in mind that all recipients using Dark Mode have selected this setting intentionally, and to circumvent the dark mode setting would go against their preferences.

For more information, please see some related content below:
* Email on Acid - Dark Theme
* Apple’s Dark - Theme
Ultimately, for Dark Mode - the email client (gmail, etc) controls how the display will be (colors inverting, removing block background colors, etc). Klaviyo cannot control the settings of dark mode since they stem from the email client. 

There was another writeup in the Community regarding dark mode as well:

Have a nice day!
Alex