Answers for ":global in css"

CSS Global variables

:root {
	--global--color-primary: #28303d;
}

a {
	color: var(--global--color-primary);
}

.social-icons a {
	background: var(--global--color-primary);
}

css global styles

html {
    font-size: 100%;
    box-sizing: border-box;
}

body {
    margin: 0px;
    padding: 0px;
    min-height: 100vh;
}

*, *::before, *::after {
    box-sizing: inherit;
}