Styleänderung durch drehen eines Tablet oder Smartphone

CSS

/* styling basics */
html {padding: 20px 0; background-color: #efefef;}
body {width: 80%; padding: 40px; margin: 0 auto; background: #fff; box-shadow: 1px 1px 5px rgba(0,0,0,0.5); font-family: Verdana, Arial, sans-serif; font-size: 14px;}

@media screen and (orientation:landscape) {
    body {background: red;}
}

@media screen and (orientation:portrait) {
    body {background: yellow;}
}