What does the sign @^ in a package.json file mean?
postcss-colormin@^4.0.3:
What does the sign @^ in a package.json file mean?
postcss-colormin@^4.0.3:
 
    
    According to the docs, the @ represents the version while the ^ represents that the specified version should be compatible with whatever version npm i will install.
Your specific example will allow npm to install the latest version of postcss-colormin that is compatible with v4.0.3.
