.classe {
width: 100%;
height: 200px;
right:0;
left:0;
background-color: #FFFFFF;
}
@-webkit-viewport{
   width:device-width;
   zoom:1;
}
@-moz-viewport{
   width:device-width;
   zoom:1;
}
@-o-viewport{
   width:device-width;
   zoom:1;
}
@-ms-viewport{
   width:device-width;
   zoom:1;
}
@viewport{
   width:device-width;
   zoom:1;
}