discourse/app/assets/stylesheets/mobile/header.scss

// --------------------------------------------------
// Discourse header
// --------------------------------------------------

#site-text-logo {
  font-size: $font-up-3;
}
@include breakpoint(mobile-small) {
  #site-text-logo {
    font-size: $font-up-2;
  }
}

.d-header {
  #site-logo {
    max-width: 9.2857em;
  }

  // some protection for text-only site titles
  .title {
    max-width: 50%;
    height: 39px;
    overflow: hidden;
    padding: 0;
    text-overflow: clip;
    display: table;
    a {
      display: table-cell;
      vertical-align: middle;
    }
  }

  button.sign-up-button {
    display: none;
  }
}

.d-header-icons {
  .d-icon {
    line-height: $line-height-medium;
  }
  .active .icon {
    &:after {
      margin-top: -1px;
    }
  }
}

#main-outlet {
  padding-top: 4.2857em;
}

.search-link .badge-category {
  display: none;
}

.search-link .topic-statuses .topic-status i {
  font-size: $font-0;
}