Gray (X11 Gray) (#BEBEBE)

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

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

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

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

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

// SCSS variable
$gray-(x11-gray): #BEBEBE;

// With RGB channels (useful for rgba() usage)
$gray-(x11-gray)-r: 190;
$gray-(x11-gray)-g: 190;
$gray-(x11-gray)-b: 190;

// Usage
.element {
    background-color: $gray-(x11-gray);
    color: rgba($gray-(x11-gray)-r, $gray-(x11-gray)-g, $gray-(x11-gray)-b, 0.8);
}