.w {
  padding: 0 20px;
  box-sizing: border-box;
}
@media (max-width: 768px) {
  .w {
    width: 100%;
  }
}
@media (min-width: 768px) and (max-width: 992px) {
  .w {
    margin: 0 auto;
    width: 768px;
  }
}
@media (min-width: 992px) and (max-width: 1200px) {
  .w {
    margin: 0 auto;
    width: 992px;
  }
}
@media (min-width: 1200px) and (max-width: 1400px) {
  .w {
    margin: 0 auto;
    width: 1200px;
  }
}
@media (min-width: 1400px) {
  .w {
    margin: 0 auto;
    width: 1400px;
  }
}