gab-social/app/javascript/gabsocial/components/column_header/column_header.scss

.column-header {
  display: flex;
  font-size: 16px;
  flex: 0 0 auto;
  cursor: pointer;
  position: relative;
  z-index: 2;
  outline: 0;
  overflow: hidden;
  background: $gab-background-container;

  body.theme-gabsocial-light & {
    background: $gab-background-container-light;
    color: $gab-default-text-light;
  }

  &--active {
    box-shadow: 0 1px 0 rgba($highlight-text-color, 0.3);

    .column-header__icon {
      color: $highlight-text-color;
      text-shadow: 0 0 10px rgba($highlight-text-color, 0.4);
    }
  }

  &:focus,
  &:active {
    outline: 0;
  }

  &__wrapper {
    position: relative;
    flex: 0 0 auto;
    overflow: hidden;

    &--active {
      &::before {
        pointer-events: none;
        z-index: 1;
        background: radial-gradient(ellipse, rgba($ui-highlight-color, 0.23) 0%, rgba($ui-highlight-color, 0) 60%);

        @include pseudo;
        @include size(60%, 28px);
        @include abs-position(35px, 0, auto, 0, false);
        @include margin-center;
      }
    }
  }

  &__icon {
    display: inline-block;
    margin-right: 5px;
  }

  &__expansion {
    overflow-x: scroll;
    overflow-y: hidden;
    white-space: nowrap;
    max-height: 0px;

    &--open {
      max-height: 55px;
    }
  }

  &__button {
    margin-left: auto;
    cursor: pointer;
    border: 0;
    padding: 0 15px;
    font-size: 16px;
    color: #fff;
    background: $gab-background-container;

    body.theme-gabsocial-light & {
      color: $gab-default-text-light;
      background: $gab-background-container-light;
    }

    &:hover {
      color: lighten($darker-text-color, 7%);
    }

    &--active {
      color: $primary-text-color;
      background: lighten($ui-base-color, 8%);

      &:hover {
        color: $primary-text-color;
        background: lighten($ui-base-color, 8%);
      }
    }
  }

  &__collapsible-inner {
    background: #3f3f3f;
    padding: 15px;

    body.theme-gabsocial-light & {
      background: #e6e6e6;
    }
  }

  &__collapsible {
    max-height: 70vh;
    overflow: hidden;
    overflow-y: auto;
    color: $darker-text-color;
    transition: max-height 150ms linear;

    &--collapsed {
      max-height: 0;
    }

    hr {
      height: 0;
      background: transparent;
      border: 0;
      border-top: 1px solid lighten($ui-base-color, 12%);
      margin: 10px 0;
    }
  }
}

.column-header-btn {
  padding: 15px;
  color: inherit;
  text-decoration: none;
  white-space: nowrap;

  &--sub {
    font-size: 14px;
    padding: 6px s10px;
  }

  &--grouped {
    margin: 6px;
  }

  &--active {
    color: $primary-text-color;
    border-radius: 10px;
    background-color: rgba($highlight-text-color, .1);
  }
}