I am trying to create a linear gradient using css variables but getting an error. This is example code:

:root {
    --Red:red;
    --Blue:blue;
}
#pageSubHeaderBackground {
    background: linear-gradient(to bottom, var(--Red) 0%, var(--Blue) 100%);
}

In Visual Studio, I am getting squiggly line under 0% and it says “Expected ,.” and the gradient is not showing up properly in the website.