HtmlTemplate.razor

@page "/Tooltip/HtmlTemplate"
@using Syncfusion.EJ2.Blazor.Buttons;
@using Syncfusion.EJ2.Blazor.Popups

@inherits SampleBaseComponent;
@using Syncfusion.EJ2
<div id="htmlTemplate" class="col-lg-12 control-section">
    <div id="customization">
        <EjsTooltip CssClass="e-tooltip-css" Content="@Template" OpensOn="Click">
            <EjsButton CssClass="e-outline text" IsPrimary="true" Content="HTML Template"></EjsButton>
        </EjsTooltip>
    </div>
</div>

@code
{
public string Template = "<div id='democontent' class='democontent'><div class='info'><h3 style='margin-top:10px'>Eastern Bluebird <hr style='margin-top:10px'></h3>" +
      "<div style='margin-top: -10px'><div style='float:left;width:57%'>The<a href='https://en.wikipedia.org/wiki/Eastern_bluebird' target='blank'> Eastern Bluebird</a>" +
  " is easily found in open fields and sparse woodland areas, including along woodland edges.These are<i>cavity-nesting birds</i>and a pair of eastern bluebirds will raise 2-3 broods annually, with 2-8 light blue or whitish eggs per brood.</div>" +
   "<div id ='bird' style='float:right;width:42%'><img id='templateImg' width='125' height='125'/></div></div>" +
    "<div style='margin-top:160px'><hr><p style='margin-top:-11px'> Eastern bluebirds can be very vocal in flocks.Their calls include a rapid, mid-tone chatter and several long dropping pitch calls.</p>" +
      "</div><p>Source:</br><a href='https://en.wikipedia.org/wiki/Eastern_bluebird' target='_blank'>https://en.wikipedia.org/wiki/Eastern_bluebird</a></p></div></div>";

}

<style>
    #htmlTemplate {
        height: 385px;
    }

    #customization {
        display: table;
        margin: 0 auto;
    }

    .e-tooltip-css {
        filter: drop-shadow(2px 5px 5px rgba(0, 0, 0, 0.25));
    }

    .text {
        text-transform: capitalize;
        width: 155px;
    }

    .democontent {
        border: 0.5px solid grey;
    }

    #bird {
        padding-top: 4px;
    }

    .info a {
        color: #2FA1E3;
    }

    #templateImg {
        background-image: url(css/tooltip/bird.png);
    }

    .info {
        padding-left: 12px;
        padding-right: 5px;
    }
</style>