Materia Breeze is a GTK theme made to match the Materia KDE theme for KDE. Made in KDE for KDE.
Enlarge the screenshots to remove blurriness.
Made for KDE
As you see in the screenshots I am using Breeze window decorations and it looks great and this is why I prefer these themes over the normal GTK themes for KDE.
Normal GTK themes do not work well in KDE but this will work perfect and perfectly matches the Materia KDE theme. Remember this is built for people using the Materia KDE theme.
With this theme you can still use Breeze title bars if you want to in your GTK apps and it works perfect. That is not so with normal Materia GTK in KDE.
I am using the Papirus icons here:
The matching KDE Plasma theme is here:
The original GTK theme MADE FOR GTK desktop environments is here:
The wallpaper is from Hypnoshot here: