Phthalo Green (#123524)

/* Background */
.element {
    background-color: #123524;
}

/* Text */
.element {
    color: #123524;
}

/* Border */
.element {
    border: 1px solid #123524;
}

/* Linear gradient to complementary */
.element {
    background: linear-gradient(
        to right,
        #123524,
        #581234
    );
}

/* Radial gradient */
.element {
    background: radial-gradient(
        circle,
        #123524,
        #581234
    );
}

// SCSS variable
$phthalo-green: #123524;

// With RGB channels (useful for rgba() usage)
$phthalo-green-r: 18;
$phthalo-green-g: 53;
$phthalo-green-b: 36;

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