macOS Mojave introduced dark mode, which uses a darker color scheme, which acts on the entire system, including the apps that come with the Mac. In addition, third-party applications can also adapt to this mode.

The latest version of macOS Mojave 10.14.4 comes with safari that supports CSS Drafts prefers-color-scheme media query , So that we can render the page in dark mode

@media (prefers-color-scheme: dark) {
  body {
    background: #232325;
    color: rgba(229, 225, 216, 0.8);
  }
}

If you do not use safari, or a website that does not support dark mode, you can try dark reader this browser plug-in.