Shared coding conventions allow teams to collaborate effectively. Writing colors in upper case makes them stand out at such, thereby making the
code easier to read.
This rule checks that hexadecimal color definitions are written in upper case.
Noncompliant code example
$white = '#ffffff'; // Noncompliant
$dkgray = '#006400';
$aqua = '#00ffff'; // Noncompliant
Compliant solution
$white = '#FFFFFF'; // Compliant
$dkgray = '#006400';
$aqua = '#00FFFF'; // Compliant
