Rebecca Purple (#663399)

/* Background */
.element {
    background-color: #663399;
}

/* Text */
.element {
    color: #663399;
}

/* Border */
.element {
    border: 1px solid #663399;
}

/* Linear gradient to complementary */
.element {
    background: linear-gradient(
        to right,
        #663399,
        #99DD55
    );
}

/* Radial gradient */
.element {
    background: radial-gradient(
        circle,
        #663399,
        #99DD55
    );
}

// SCSS variable
$rebecca-purple: #663399;

// With RGB channels (useful for rgba() usage)
$rebecca-purple-r: 102;
$rebecca-purple-g: 51;
$rebecca-purple-b: 153;

// Usage
.element {
    background-color: $rebecca-purple;
    color: rgba($rebecca-purple-r, $rebecca-purple-g, $rebecca-purple-b, 0.8);
}