dark7.js

if (window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)') {
    var windowPrefersDark = window.matchMedia('(prefers-color-scheme: dark)');
    var systemColorMode = windowPrefersDark.matches ? 'dark' : 'light';

    // need to check in case doesn't exist like with Safari 13.x
    if (
        'addEventListener' in windowPrefersDark &&
        typeof windowPrefersDark.addEventListener === 'function'
    ) {
        windowPrefersDark.addEventListener('change', (event) => {
            systemColorMode = event.matches ? 'dark' : 'light';
        });
    }
}