@media (prefers-color-scheme: light) {
body {
    background-attachment : fixed;
    background-image : url("background-light.jpg");
    background-position : center;
    background-repeat : no-repeat;
    background-size : cover;
}

div {
    background-color : rgba(200, 200, 200, 0.8);
}

.thing {
    border-color : #888;
}
}