.nav-header{
  width: 100%;
  height: 90px;
  background-color: #12193a; 
  line-height: 90px;
}

.mask-box{
  position: fixed;
  top: 0;
  bottom: 0;
  right: 0;
  left: 0;
  background-color: rgba(0, 0, 0, 0.5);
  z-index: 9;
  overflow: hidden;
  display: none;
}
/* 自适应 移动端 */
@media (max-width: 767px) {
  .nav-header{
    height: 4rem;
    line-height: 4rem;
  }
}