devto-clone/src/Scss/_mediaQueries.scss

@media only screen and (max-width: 1024px) {
  .header {
    padding: 1rem;
  }
  .main-container {
    grid-template-columns: 2fr 5fr;
    padding: 1rem;
  }
  .rightBar {
    display: none;
  }
}

@media only screen and (max-width: 768px) {
  .main-container {
    grid-template-columns: 100%;
    padding: 1rem;
  }
  .header .headerContainer {
    &__hamburgerMenu {
      display: block;
    }

    &__searchBox {
      display: none;
    }

    &__right {
      .hidden-search {
        display: flex;
      }
      button {
        display: none;
      }
    }
  }

  .leftBar {
    display: none;
  }
}

@media only screen and (max-width: 640px) {
  .main-content {
    header {
      nav {
        display: none;
      }
      select {
        display: block;
      }
    }
  }
  .hidden-mobile {
    display: none;
  }
  .show-mobile {
    display: inline-block;
  }
  .header .dropdown-menu {
    position: absolute;
    right: 0;
    left: 0;
    margin: 0 0.5rem;
    ul li {
      padding: 1rem;
    }
  }
}