media query for mobile device only code example

Example 1: media query

@media only screen and (max-width: 800px) {
  body {
    background-color: ; /*your color*/
  }
}

Example 2: media queries

@media all and (max-width: 699px) and (min-width: 520px) {
   ul li a {
    padding-left: 21px;
    background: url(../images/email.png) left center no-repeat;
  }
}