Hi, you have to identify your selector :
if an id, it's '#'
if a class, it's '.'
to define a constant ( or more ) in CSS :
html{
--button-background-color : #00A36C;
}
#text-danger {
color:var(--button-background-color);
}
.fa .fa-plus {
color:var(--button-background-color);
}
.glyphicon #glyphicon-plus {
color:var(--button-background-color);
}
#text-danger,.fa .fa-plus, .glyphicon #glyphicon-plus{
color:var(--button-background-color);
}