The @media query specifically for ‘phones’ is..
@media (max-width: 480px) { ... }
But, you may want to remove the padding/margin for any smaller screen sizes. By default, Bootstrap adjusts margins/padding to the body, container and navbars at 978px.
Here are some queries that have worked (in most cases) for me:
@media (max-width: 978px) {
.container {
padding:0;
margin:0;
}
body {
padding:0;
}
.navbar-fixed-top, .navbar-fixed-bottom, .navbar-static-top {
margin-left: 0;
margin-right: 0;
margin-bottom:0;
}
}
Update for Bootstrap 4
Use the new responsive spacing utils which let you set padding/margins for different screen widths (breakpoints):
https://stackoverflow.com/a/43208888/171456