Shadow Blue (#778BA5)

/* Background */
.element {
    background-color: #778BA5;
}

/* Text */
.element {
    color: #778BA5;
}

/* Border */
.element {
    border: 1px solid #778BA5;
}

/* Linear gradient to complementary */
.element {
    background: linear-gradient(
        to right,
        #778BA5,
        #BEA88C
    );
}

/* Radial gradient */
.element {
    background: radial-gradient(
        circle,
        #778BA5,
        #BEA88C
    );
}

// SCSS variable
$shadow-blue: #778BA5;

// With RGB channels (useful for rgba() usage)
$shadow-blue-r: 119;
$shadow-blue-g: 139;
$shadow-blue-b: 165;

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