Prussian Blue (#003153)

/* Background */
.element {
    background-color: #003153;
}

/* Text */
.element {
    color: #003153;
}

/* Border */
.element {
    border: 1px solid #003153;
}

/* Linear gradient to complementary */
.element {
    background: linear-gradient(
        to right,
        #003153,
        #A64400
    );
}

/* Radial gradient */
.element {
    background: radial-gradient(
        circle,
        #003153,
        #A64400
    );
}

// SCSS variable
$prussian-blue: #003153;

// With RGB channels (useful for rgba() usage)
$prussian-blue-r: 0;
$prussian-blue-g: 49;
$prussian-blue-b: 83;

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