<div class="input-group-btn">
        <button type="button"  (click)="isCollapsed = !isCollapsed" class="btn btn-default dropdown-toggle selector calendarSelector"
          style="margin-left:-1" [attr.aria-expanded]="!isCollapsed" aria-controls="collapseExample">
          <span class="glyphicon glyphicon-calendar calendarIcon"></span>
          <span class="glyphicon glyphicon-menu-down"></span>
        </button>
        <div id="collapseExample" [ngbCollapse]="isCollapsed"  class="dropdown-menu ">
          <ngb-datepicker  #d1 style="padding:30px; font-size: 11px !important;border:none;line-height: 1px;
          letter-spacing: 1px;" (click)='searchArticleByDate();isCollapsed = !isCollapsed ' [(ngModel)]="model1" name="something" #c1="ngModel"></ngb-datepicker>
        </div>


      </div>