hugo-theme-zzo/assets/sass/layout/_header.scss

.header {
  @include flexbox();
  @include align-items(center);
  @include justify-content(center);
  @include flex-direction(column);

  .title {
    font-family: $title-font;
    font-weight: 900;
  }
}

.site-header {
  @include flexbox();  
  @include justify-content(center);
  @include flex-direction(column);

  &__title {
    line-height: 1.1;
    font-weight: 700;
    font-family: $title-font;
  }

  &__subtitle {
    line-height: 1.2;
    font-family: $title-font;
  }

  &__align-left {
    @include align-items(flex-start);
  }

  &__align-center {
    @include align-items(center);
  }

  &__align-right {
    @include align-items(flex-end);
  }
}