how to force landscape in the view of mobile

Hi i wanna add code to force the mobile version in landscape only, but i tried code as 

@media screen and (orientation: portrait) {
.main {
-webkit-transform:rotate(-90deg);
-moz-transform: rotate(-90deg);
-ms-transform: rotate(-90deg);
transform: rotate(-90deg);
width: 100vh;
 height: 100vh;
overflow: hidden;
  }
}
@media screen and (orientation: landscape) {
.main {
 -webkit-transform:rotate(0);
-moz-transform: rotate(0);
-ms-transform: rotate(0);
transform: rotate(0)
}
}

it doesnt really work, wondering if anyone have the same problem and can provide me some advice. a lot thankx

Hi,

What is your site url?