Update on 2020-12-30: Use this way to modify system files on Big Sur!
Update for big sur! (2020-12-07)
- The big sur doesn't allow making root volume writable anymore, since it's a snapshot now.
Follow these instructions to modify system files (or see details here):
The WindowFrame_WindowShapeEdges is not in the
DarkSystemAppearance.carfor the dark theme) anymore but in the
DarkAqua.carfor the dark theme).
The old ThemeEngine (v2) doesn't support the big sur anymore, you need to use the v3 branch released by @jslegendre.
Below is the original post:
Tested on Catalina 10.15.3 | Last Updated: Wed Apr 8 22:32:32 CST 2020
Disable SIP (There are lots tutorial online to teach you how to do it, will not expand the details here)
Install ThemeEngine (Note: only this build supports catalina 10.15)
Make system volume writable:
sudo mount -uw /
Backup original theme resources:
rsync -rI /System/Library/CoreServices/SystemAppearance.bundle/Contents/Resources/ .
Create a new folder for editing the theme file:
mkdir edited && cd edited
Copy a theme file here and edit it (
SystemApperance.carfor the light theme and
DarkAquaAppearance.carfor the dark theme). Take
SystemAppearance.caras an example:
cp ../SystemAppearance.car .
open . # Open this folder with finder
Double click the file
SystemAppearance.carto edit it with ThemeEngine that we installed before
- Replace masks to squares
- Replace base images to pure transparent images
Save all changes, replace the modified
SystemAppearance.carback to the system path.
sudo cp SystemAppearance.car /System/Library/CoreServices/SystemAppearance.bundle/Contents/Resources/