Remotely/Server/Components/TabControl/TabControl.razor

<ul class="nav nav-tabs">
    <CascadingValue Value="this">
        @TabHeaders
    </CascadingValue>
</ul>
<div class="tab-content">
    <CascadingValue Value="this">
        @TabContents
    </CascadingValue>
</div>


@code {
    [Parameter]
    public RenderFragment TabHeaders { get; set; }

    [Parameter]
    public RenderFragment TabContents { get; set; }

    [Parameter]
    public string InitialActiveTab { get; set; }

    public string ActiveTab { get; set; }

    protected override void OnInitialized()
    {
        ActiveTab = InitialActiveTab;
    }

    public void SetActiveTab(TabHeader header)
    {
        ActiveTab = header.Name;
        StateHasChanged();
    }
}