Electric Crimson (#FF003F)

/* Background */
.element {
    background-color: #FF003F;
}

/* Text */
.element {
    color: #FF003F;
}

/* Border */
.element {
    border: 1px solid #FF003F;
}

/* Linear gradient to complementary */
.element {
    background: linear-gradient(
        to right,
        #FF003F,
        #00FFC0
    );
}

/* Radial gradient */
.element {
    background: radial-gradient(
        circle,
        #FF003F,
        #00FFC0
    );
}

// SCSS variable
$electric-crimson: #FF003F;

// With RGB channels (useful for rgba() usage)
$electric-crimson-r: 255;
$electric-crimson-g: 0;
$electric-crimson-b: 63;

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