.login-page, .register-page {
    /**
       (2022-04-01)
       (1) Bootstrap 4 colors , https://colorswall.com/palette/3
       (2) CSS background-color Property , https://www.w3schools.com/cssref/pr_background-color.asp
       (3) CodePen Home Jumbotron background image opacity - Bootstrap 4 , https://codepen.io/JacobLett/pen/vPQKWd
     */
    background-image: linear-gradient(to bottom, rgba(91,192,222,0.7) 0%,rgba(91,192,222,0.9) 100%), url("library/images/background/mcen-1200x800.jpg");
    background-size: cover;
    background-position: center center;
}