Template

<div id="target" class="col-lg-12 control-section" style="height:400px;">
    <ejs-button id="targetButton" e-ripple="true" content="OPEN DIALOG"></ejs-button>
    <ejs-dialog id="dialog" cssClass="custom-template" height="85%" width="45%" target="#target"  header="<img class='img2' src='https://ej2.syncfusion.com/demos/src/dialog/images/1.png' alt='header image'><div title='Nancy' class='dlg-template e-icon-settings'> Nancy </div>"
                showCloseIcon="true" created="onLoad" footerTemplate="<input id='inVal' class='e-input' type='ext' placeholder='Enter your message here!'/><button id='sendButton' class='e-control e-btn e-primary' data-ripple='true'>Send</button>">
        <e-content-template>
            <div class='dialogContent'><span class='dialogText'>Greetings Nancy! When will you share me the source files of the project?</span></div>
        </e-content-template>
    </ejs-dialog>
</div>

<style>

    #dialog .e-icon-settings::before {
        padding: 3px;
        font-size: 15px;
    }

    #sendButton {
        top: 5px;
        position: relative;
        right: 7px;
    }

    .custom-template.e-dialog .e-dlg-header-content {
        border-bottom: none;
        padding: 11px;
    }

    .e-dialog .e-footer-content {
        right: 7px;
    }

    .e-dialog .e-dlg-header-content {
        background-color: #007DD1;
        padding: 10px;
    }

        .e-dialog .e-dlg-header-content .e-btn.e-dlg-closeicon-btn {
            top: 5px;
            left: -11px;
        }

    .e-dialog .e-dlg-header {
        position: relative;
    }

    .e-dialog .e-dlg-content {
        padding: 0;
    }

    #sendbtn {
        margin-right: -17px;
        margin-top: -2%;
    }

    .e-open-icon::before {
        content: '\e782';
    }

    .e-dialog .e-dlg-header > .img2 {
        height: 36px;
        width: 36px;
        border-radius: 50%;
        vertical-align: middle;
        display: inline-block;
    }

    .e-dialog .e-dlg-header .dlg-template {
        display: inline-block;
        padding: 0 10px;
        vertical-align: middle;
        height: 30px;
        line-height: 30px;
        color: #fff;
    }

    .e-dialog .e-dlg-header-content .e-btn .e-btn-icon {
        margin-top: -3px;
    }

    .custom-template .e-input {
        width: 75%;
        float: left;
        height: 18px;
    }


    .dialogContent .dialogText {
        font-size: 13px;
        padding: 5%;
        word-wrap: break-word;
        border-radius: 6px;
        text-align: justify;
        font-style: initial;
        display: block;
    }

    .dialogContent .dialogText {
        background-color: #f5f5f5;
    }

    .custom-template.e-dialog .e-footer-content {
        border-top: 0.5px solid #949494;
        padding-left: 31px;
    }

    .dialogContent {
        display: block;
        font-size: 15px;
        word-wrap: break-word;
        text-align: center;
        font-style: italic;
        border-radius: 6px;
        padding: 3%;
        position: relative;
        top: 25px;
    }

    .e-dialog .dialogContent {
        top: 20px;
    }

    .control-wrapper .e-control.e-dialog {
        width: 30%;
    }

    .e-dialog .e-dlg-header-content .e-icon-dlg-close {
        color: #fff;
    }

    .e-dialog .e-btn.e-dlg-closeicon-btn:hover span {
        color: #8ECBFF;
    }

    .e-dialog .e-dlg-header-content .e-btn.e-dlg-closeicon-btn:hover {
        background-color: rgba(255,255,255, 0.10);
    }

    .e-dialog .e-dlg-header-content .e-btn.e-dlg-closeicon-btn:focus {
        background-color: rgba(255,255,255, 0.10);
    }

    .e-dialog .e-dlg-header-content .e-btn.e-dlg-closeicon-btn:active .e-icon-dlg-close {
        color: #fff;
    }

    .e-dialog .e-dlg-header-content .e-btn.e-dlg-closeicon-btn:focus .e-icon-dlg-close {
        color: #fff;
    }

    .e-dialog .e-dlg-header-content .e-btn.e-dlg-closeicon-btn:hover .e-icon-dlg-close {
        color: #fff;
    }
</style>
<script>
    var validText;
    document.getElementById('targetButton').onclick = function () {
        var dialogObj = document.getElementById('dialog').ej2_instances[0];
        dialogObj.show();
    };
    function onLoad() {
        (document.getElementById('inVal')).onkeydown = function (e) {
            if (e.keyCode === 13 && validText != "") {
                updateTextValue();
            }
        };
        (document.getElementById('sendButton')).onkeydown = function (e) {
            if (e.keyCode === 13 && validText != "") {
                updateTextValue();
            }
        };
        document.getElementById('sendButton').onclick = function (e) {
            updateTextValue();
        }
    }
    function updateTextValue() {
        var enteredVal = document.getElementById('inVal');
        var dialogTextElement = document.getElementsByClassName('dialogText')[0];
        var dialogTextWrap = document.getElementsByClassName('dialogContent')[0];
        if (enteredVal.value !== '') {
            dialogTextElement.innerHTML = enteredVal.value; enteredVal.value = '';
        }
    }

</script>

public class HomeController : Controller
{
    public ActionResult Index()
    {
        return View();
    }
}