Hummingbird and Divi Theme

When I turn on the Assets Optimization, my child theme style is overridden by the parent theme, I moved the child theme CSS to the footer, but some styles still wrong, for example, the headings font and menu, this is the right style https://www.screencast.com/t/B3osG43R5lbw, when assets optimization activated https://www.screencast.com/t/ZWOdAOjVx4