body{margin: 0; padding: 0; background: #000; display: flex; width: 100%; height: 100%; justify-content: center; align-items: center}
.landscape {width: 100%; height: 100dvh; display: block; background: url(home_html/landing-page.jpg); background-position: center; background-size: cover;}
.portrait {display: none}

@media screen and (max-width:800px)
{
body{margin: 0; padding: 0; background: #000; display: flex; width: 100%; height: 100dvh; justify-content: center; align-items: center}
.landscape {display: none}
.portrait {display: block}
}