breeze-alphablack VS firefox-sweet-theme

Papirus (Follows Color Theme): https://github.com/Zren/breeze-alphablack/tree/papirus/icons

The panel's appearance is controlled by your theme's SVGs. You will have to modify them to get the panel to change color. To make it easier, there is the Breeze AlphaBlack theme, which offers readymade command-line tools to change its panel color and transparency: https://github.com/Zren/breeze-alphablack.

Breeze AlphaBlack (https://store.kde.org/p/1084931/) automatically installs a widget which can modify the theme to change the tasks.svg move the line to the edge of the screen.

Have you looked into breeze-alphablack.

My best alternative so far has been using Lightly to remove the details that I find unnecessary in Breeze such as borders on almost every element. I also use Breeze AlphaBlack to be able to easily change the taskbar colors.

I use pywall basically to update the system colors and use Breeze Alphablack to change the theme colors dynamically.

Some themes like Breeze AlphaBlack have easily-configurable colours and transparency.

If you want sweet theming this theme does it well https://github.com/EliverLara/firefox-sweet-theme

It's a rabbit hole that can keep you busy for a while, but the results can look beautiful

Sweet Dark Kvantum along with the Firefox userChrome (same dev) is straight 🔥

It's a feature so that you can drag the window easily if your tab bar is full. You can get rid of it by enabling the title bar, but that's even uglier imo, before - after. Another alternative is just using a theme with an entirely different layout, like firefox-sweet, not sure about this one specifically on windows tho.