.header-main {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
}

.main-nav__dropdown {
  max-height: calc(100vh - 72px);
  overflow: auto;
}

@media only screen and (max-width: 1262px) {
  .main-nav {
    max-height: calc(100vh - 56px);
    overflow: auto;
  }
}