peertube-plugin-livechat/conversejs/custom/plugins/tasks/styles/muc-task-drag.scss

.conversejs {
  livechat-converse-muc-task {
    &.livechat-drag-bottom-half .task-line {
      border-bottom: 4px solid blue;
    }

    &.livechat-drag-top-half .task-line {
      border-top: 4px solid blue;
    }
  }

  livechat-converse-muc-task-list {
    &.livechat-drag-bottom-half .task-list-line {
      border-bottom: 4px solid blue;
    }

    &.livechat-drag-top-half .task-list-line {
      border-top: 4px solid blue;
    }
  }
}