/* DESKTOP */
@media screen and (min-width: 1000px) {
     body {background-color: #333333; color: #FFFFFF; margin: 25px;}
     .well {color: #000000;}
     .tablet {display: none;}
     .mobile {display: none;}
     }

/* TABLET */
@media screen and (max-device-width: 780px) {
     body {background-color: #0000FF; color: #FFFFFF; margin: 25px;}
     .well {color: #000000;}
     .desktop {display: none;}
     .mobile {display: none;}
     }