Medienabfrage
@media only screen and (max-width: 600px) {
body {
background-color: lightblue;
}
}
Collared Lizard
@media only screen and (max-width: 600px) {
body {
background-color: lightblue;
}
}<input type="tel" id="phone" name="phone" pattern="[0-9]{3}-[0-9]{2}-[0-9]{3}">