constructor(rootEl, theme) {
    this.container = $(rootEl).tabs({
      activate: (event, ui) => {
        this.activeTabEl = ui.newTab
        this.activeTabId = ui.newTab.data('tab')
      }
    })
    this.tabBar = this.container.find('#tab-header')
    this.tabs = []
    this.totalTabsCreated = 0 // Counter for unique tab ids
    this.theme = theme
    this.init()
  }
Create tabs container and set theme

@param {Element} rootEl Container element for tabs
@param {String} theme Theme for the tab