Description

When using a css variable in colors or in serie color with area chart type, all fill options depending of color are not working correctly, in this example case, opacity is not correctly set.

Steps to Reproduce

fill: {
    type: 'solid',
    opacity: .25
},
series: [{
    name: 'Total Views',
    color: "var(--test-blue)",
    data: [...]
}],

Expected Behavior

Area color must have 25% opacity

Actual Behavior

Opacity is not at 25% like I will !

Screenshots

Reproduction Link

https://codepen.io/dragonofmercy/pen/VYaBOdV