Currently most popular browsers and apps implemented "Dark mode" seamlessly without the need to restart the browser when the operating system switched the app theme to dark. With Opera as an exceptional case which I need to restart the Opera every day when my Windows app theme switched to dark mode because of sunset. To me, I think there should be an option to automatically switch like what other apps or browsers did. I knew some may not like the switch of theme automatically, that's why I suggest at least "light", "dark", "system default" these three options for color choosing. Here attached the current situation from other browsers developer version or similar version:

Microsoft Edge:

Google Chrome:
No option to choose, follow system by default, can install more themes

Mozilla Firefox:

Firefox Alpenglow is a theme that change dynamically based on system color

Opera GX:
Dark themes only

Vivaldi:

Can change theme with scheduled time and let user to choose which theme for both light theme and dark theme. I think it is the best option but it doesn't change their start page wallpaper with theme which the developers said they are working on that.

Brave:

Hopefully, I can no longer manually restart Opera in the near future.

@balbert

I am excited with Version:79.0.4100.0. Thank you Opera Team.

@Danio9900
It would be great to introduce a "System" mode preset that switches to "Polar Wind" in system app light mode and "Aurora" in system app dark mode. Perhaps we could rearrange the order to have "Light/Dark/System" at the primary level, with Dynamic and Classic options underneath? And it appears that the dynamic theme isn’t animated in any tabs apart from "Speed Dial."

I don't have this issue, but I think it can be solved by resetting the status or configuration of Aria. Here are the steps to follow:

1. Right-click on a blank space in Aria.
2. Click on "Inspect element" to open a new window (DevTools).
   
3. (Optional) Click on "Console" in the top navigation bar to check for any errors. Capture them and report them to opera developers and see if they notice.
4. Click on "Application" in the top navigation bar.
5. Select "Storage" from the left sidebar.
6. Click on "Clear site data" with all checkboxes checked, as shown in the image below.
   
7. Quit and restart Opera.
8. Aria's status and configuration will be reset, and you can check if the problem is resolved.
   

@balbert

I am excited with Version:79.0.4100.0. Thank you Opera Team.

Currently most popular browsers and apps implemented "Dark mode" seamlessly without the need to restart the browser when the operating system switched the app theme to dark. With Opera as an exceptional case which I need to restart the Opera every day when my Windows app theme switched to dark mode because of sunset. To me, I think there should be an option to automatically switch like what other apps or browsers did. I knew some may not like the switch of theme automatically, that's why I suggest at least "light", "dark", "system default" these three options for color choosing. Here attached the current situation from other browsers developer version or similar version:

Microsoft Edge:

Google Chrome:
No option to choose, follow system by default, can install more themes

Mozilla Firefox:

Firefox Alpenglow is a theme that change dynamically based on system color

Opera GX:
Dark themes only

Vivaldi:

Can change theme with scheduled time and let user to choose which theme for both light theme and dark theme. I think it is the best option but it doesn't change their start page wallpaper with theme which the developers said they are working on that.

Brave:

Hopefully, I can no longer manually restart Opera in the near future.