signal-desktop/stylesheets/_index.scss

.conversation-stack,
.new-conversation,
.inbox,
.gutter {
  height: 100%;
  overflow: hidden;
  position: relative;
}

.expired {
  .conversation-stack,
  .gutter {
    height: calc(100% - 48px);
  }
}

.scrollable {
  height: 100%;
  overflow: auto;
}

.gutter {
  @include light-theme {
    background-color: $color-gray-02;

    ::-webkit-scrollbar-track {
      background: $color-gray-02;
    }
    ::-webkit-scrollbar-thumb {
      border: 2px solid $color-gray-02;
    }
  }
  @include dark-theme {
    background-color: $color-gray-80;

    ::-webkit-scrollbar-track {
      background: $color-gray-80;
    }
    ::-webkit-scrollbar-thumb {
      border: 2px solid $color-gray-80;
    }
  }

  float: left;
  width: $left-pane-width;
  user-select: none;

  .content {
    overflow-y: scroll;
    max-height: calc(100% - 88px);
  }
}

.left-pane-placeholder {
  height: 100%;
}
.left-pane-wrapper {
  height: 100%;
}

.conversation.placeholder {
  text-align: center;
  user-select: none;

  .container {
    position: absolute;
    height: 100%;
    width: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
  }
  .content {
    display: inline-block;
  }

  h3 {
    font-size: large;
  }
}