Popover's position is changed on focus

Question

I am using ng2-bootstrap popover and having problems when trying to tab thru the spans inside the popover. Here is the code:

<ng-template #popDefinitionsTemplate>
    <h4 #popDefinitionsHeader [autoFocus]="true" tabindex="0">{{definitions.title}}</h4>
    <hr>
    <div *ngFor="let item of definitions.definitionItems;">
         <span tabindex="0"><b>{{item.term}}</b></span>
         <span tabindex="0"> - {{item.termDefinition}}</span>
    </div>
</ng-template>
<button class="btn btn-secondary btn-finish-later pull-right"
        [popover]="popDefinitionsTemplate"
        placement="bottom">
</button>

Whenever I tab thru the spans included in *ngFor, popover-container 's "left" style property is changed from 1066px to 1068px.

Is there a way to prevent the changing of style property when tabbing?