radzen-blazor/Radzen.Blazor/Rendering/ChartTooltip.razor

<div class="rz-chart-tooltip @Class">
    <div class="rz-chart-tooltip-content" style="@Style">
    @if (ChildContent != null)
    {
        @ChildContent
    }
    else
    {
        <div class="rz-chart-tooltip-title">@Title</div>
        <label>@($"{Label}:")
            <span class="rz-chart-tooltip-item-value">@Value</span>
        </label>
    }
    </div>
</div>

@code {
    [Parameter]
    public string Style { get; set; }

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

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

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

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

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