<style>
/* Metallic Theme */
body {
background-image: linear-gradient(to bottom, #343434, #555555);
background-size: 100% 300px;
background-position: 0% 100%;
transition: background-position 0.5s ease-out;
}

body.leaved {
background-position: 100% 100%;
}

@media only screen and (max-width: 768px) {
body {
background-image: linear-gradient(to bottom, #343434, #555555);
background-size: 100% 200px;
}
}

/*... rest of the CSS code... */
</style>
