Css for different mobile phones

@media
screen and (-webkit-min-device-pixel-ratio:0),        /* iPhone */
only screen and (-webkit-min-device-pixel-ratio: 2),  /* iPhone4 */
only screen and (max-device-width: 1024px),           /* Android - Hdpi */
screen and (-webkit-device-pixel-ratio: 1.5),         /* Android - Hdpi */
screen and (-webkit-device-pixel-ratio: 1.0),         /* Android - Mdpi */
screen and (-webkit-device-pixel-ratio: 0.75)         /* Android - Ldpi */
{
  /***********************/
  /* Register            */
  /***********************/
  .account_register #header {
    width: 100%;
  }

  .account_register #header_search {
    width: 200px;
  }

  .account_register #header_search label {
    display: none;
  }

  .account_register #header_search input.text {
    width: 150px;
  }

  .account_register .columns.layout_4 .column_1 {
    margin: 0;
    width: 100%;
  }

  .account_register .column_2 {
    display: none;
  }
}

/************************************/
/*          Device Specific         */
/************************************/

/**** iPhone ************************/
@media screen and (-webkit-min-device-pixel-ratio:0) {
}

/**** iPhone4 ***********************/
@media only screen and (-webkit-min-device-pixel-ratio: 2) {
}

/**** iPad **************************/
@media only screen and (max-device-width: 1024px) {
}

/**** Android - Hdpi ****************/
@media screen and (-webkit-device-pixel-ratio: 1.5) {
}

/**** Android - Mdpi ****************/
@media screen and (-webkit-device-pixel-ratio: 1.0) {
}

/**** Android - Ldpi ****************/
@media screen and (-webkit-device-pixel-ratio: 0.75) {
}


/************************************/
/*     Orientation Specific         */
/************************************/

/**** Landscape ****************/
@media only screen and (max-width: 480px) and (orientation: landscape) {
}

/**** Portrait  ****************/
@media only screen and (max-width: 480px) and (orientation: portrait) {
  .account_register #header .logo {
    float: none;
  }

  .account_register #header_search {
    display: block;
    float: none;
    margin: 0.5em 0;
    position: static;
    width: 210px;
  }

  .account_register #header_search label {
    display: none;
  }

  .account_register #header_search input.text {
    width: 165px;
  }

  .account_register #header .nav {
    float: none;
    position: static;
  }

  .account_register #footer ul {
    margin-right: 3em;
  }
}