How do I set the brand color for my catalog? Can I extract colors directly from my company logo? Can I also change the colors of the backend system interface?

Set your brand color in Organization & Settings → Company Profile → Appearance & Language → Catalog Appearance. You can enter a #RRGGBB hex code, use the color picker, use an eyedropper tool (available in some browsers), or click "Extract Color from Company Logo" (after uploading your logo first). You can also "Restore Defaults." The interface shows nearby colors and complementary color suggestions below; click on a color swatch to copy the hex code. Brand color is company-wide and applies to all your catalogs. Hover color and light background color are calculated automatically and don't need separate configuration. The login page can also use the same brand color. This setting only affects the catalogs and login page that customers see, not the colors of your backend system interface. Backend interface color customization is not yet available in V5 but is planned for a future release.