In Affinity Designer it seems there is no way to change the opacity of global colors. This is becoming frustrating when designing UIs. Opacity is an integral part of color schemes in Google's Material Design; it completely depends on opacity to create visual hierarchy. From Google's Material Design Guidelines: "Using opacity instead of shifting colors often creates better contrast and relative luminance. For example, gray text (#727272) becomes hard to read if the background color changes to magenta."
Is this feature on your road map?
