Sierra Breeze is a fork of Breeze Window decoration that aims to mimic the OSX Sierra titlebar buttons.
Debian/Ubuntu users can install by using the PPA maintained by Thomas Pietrowski:
sudo add-apt-repository ppa:thopiekar/sierrabreeze
sudo apt update
sudo apt install sierrabreeze
SierraBreeze can also be installed from the AUR using
yaourt sierrabreeze-kwin-decoration-git
SierraBreeze can also be installed with zypper
zypper addrepo https://download.opensuse.org/repositories/home:trmdi/openSUSE_Tumbleweed/home:trmdi.repo
zypper refresh
zypper install sierra-breeze
or using the binary package https://software.opensuse.org//download.html?project=home%3Atrmdi&package=sierra-breeze.
There are some dependencies you'll need to build from source. Some people suggested using the following commands:
sudo apt install build-essential libkf5config-dev libkdecorations2-dev libqt5x11extras5-dev qtdeclarative5-dev extra-cmake-modules libkf5guiaddons-dev libkf5configwidgets-dev libkf5windowsystem-dev libkf5coreaddons-dev gettext
sudo pacman -S kdecoration qt5-declarative qt5-x11extras # Decoration
sudo pacman -S cmake extra-cmake-modules # Installation
sudo dnf install cmake extra-cmake-modules
sudo dnf install "cmake(Qt5Core)" "cmake(Qt5Gui)" "cmake(Qt5DBus)" "cmake(Qt5X11Extras)" "cmake(KF5GuiAddons)" "cmake(KF5WindowSystem)" "cmake(KF5I18n)" "cmake(KDecoration2)" "cmake(KF5CoreAddons)" "cmake(KF5ConfigWidgets)"
In order to install the theme and add it to your decorations do the following:
git clone https://github.com/ishovkun/SierraBreeze
cd SierraBreeze
mkdir build
cd build
cmake .. -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_BUILD_TYPE=Release -DKDE_INSTALL_LIBDIR=lib -DBUILD_TESTING=OFF -DKDE_INSTALL_USE_QT_SYS_PATHS=ON
sudo make install
To avoid logging out, issue
kwin_x11 --replace &
That is it! Your new decoration theme should appear in Settings → Application Style → Window Decorations.