Answers for "back background image effect css"

php code to display a div with background fade

body {
    background: url('http://placehold.it/1600x1200') no-repeat center center fixed;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover;
}

css backdrop filter grayscale

backdrop-filter: grayscale(30%);