Not able to navigate ngbpopover close button using tab

问题

I have used the separate close button to close the popover but not able to navigate to the close button using keyboard.

 "@ng-bootstrap/ng-bootstrap": "^4.1.0",

code:

<div>
      <ng-template #popContent>
        <span id="glossary">  {{element.description| glossary:glossaryDescription}}</span>
        <button class="close" (click)="p.close()" tabindex="0"><img src="assets/icons/close.svg"></button>

      </ng-template>
      <button class="popoverLink" [ngbPopover]="popContent" [autoClose]="false"
              triggers="manual" #p="ngbPopover" (click)="p.open()" placement="top-right bottom-right"
              container="body"
              html="true" popoverClass="custom-popover">

        {{split(element.description)[0]}}
      </button>
      /{{split(element.description)[1]}}
    </div>

来源：https://stackoverflow.com/questions/57959569/not-able-to-navigate-ngbpopover-close-button-using-tab