Font change and styling of HTML email body in MailKit
<p>after allowing the access of less secure apps <a href="https://www.google.com/settings/security/lesssecureapps" rel="nofollow noreferrer">here</a> I was able to send my self an email using gmail with inline styling.</p>

<pre><code>using MailKit.Net.Smtp;   // for SmtpClient
using MimeKit;  // for MimeMessage, MailboxAddress and MailboxAddress

var message = new MimeMessage();
message.From.Add(new MailboxAddress("Hasan Yousef", "hasan@gmail.com"));
message.To.Add(new MailboxAddress("Personal", "hasan@gmail.com"));
message.To.Add(new MailboxAddress("Office", "hasan@offfice.com.sa"));
message.Subject = "How you doin'?";

string num = "13.5 million";

var bodyBuilder = new BodyBuilder();
bodyBuilder.HtmlBody = @"
&lt;div style='background-color:black;color:white;padding:20px; box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);'&gt;
            &lt;h1 style='text-align: center; font-family: 'Sigmar One', cursive;'&gt;Welcome to Ben's Minecraft&lt;/h1&gt;
            &lt;img src='https://www.bk-international.com/mahout_cms/project/themes/default/images/de/logo.png' alt='HTML5' style='width:84px;height:47px'&gt;&lt;br&gt;
            &lt;a href='https://www.bk-international.com/de_en/'&gt;Bischof + Klein&lt;/a&gt;
            &lt;h2&gt;London&lt;/h2&gt;
            &lt;p&gt;London is the capital city of England. 
            It is the most populous city in the United Kingdom, with a metropolitan area of over &lt;span style='color:red'&gt;
&lt;i&gt;&lt;b&gt;" + num + 
@"&lt;/b&gt;&lt;/i&gt;&lt;/span&gt;
inhabitants.&lt;/p&gt;
            &lt;p style='background-color:#ffc;color:black;'&gt; Hope you liked the above&lt;/p&gt;
            &lt;table&gt;
            &lt;tr&gt;
                &lt;th&gt;Name&lt;/th&gt;
                &lt;th&gt;Description&lt;/th&gt;
            &lt;/tr&gt;
            &lt;tr&gt;
                &lt;td&gt;A&lt;/td&gt;
                &lt;td&gt;Description of A&lt;/td&gt;
            &lt;/tr&gt;
            &lt;tr&gt;
                &lt;td&gt;B&lt;/td&gt;
                &lt;td&gt;Description of B&lt;/td&gt;
            &lt;/tr&gt;
            &lt;/table&gt;
            &lt;ol&gt;
                &lt;li&gt;London&lt;/li&gt;
                &lt;li&gt;Paris&lt;/li&gt;
                &lt;li&gt;Tokyo&lt;/li&gt;
            &lt;/ol&gt;
            &lt;img src='https://www.bk-international.com/mahout_cms/project/themes/default/images/subhead.png' alt='HTML5' style='width:193px;height:9px'&gt;
&lt;/div&gt;         
            ";

message.Body = bodyBuilder.ToMessageBody();

/*       message.Body = new TextPart("plain")
        {
            Text = @"Hey Chandler,I just wanted to let you know that Monica and I were going to go play some paintball, you in?-- Joey"
        };
*/
using (var client = new SmtpClient())
{
      client.Connect("smtp.gmail.com", 587);
      client.AuthenticationMechanisms.Remove("XOAUTH2");  // due to enabling less secure apps access

      client.Authenticate("hasan@gmail.com", "myEmailPassward");
      client.Send(message);
      client.Disconnect(true);
}
</code></pre>

<p>My question is:
How can I change the font, I tried adding the head script below but it did not work.</p>

<pre><code>&lt;head&gt;
   &lt;link href='https://fonts.googleapis.com/css?family=Sigmar+One' rel='stylesheet' type='text/css'&gt;
&lt;/head&gt;
</code></pre>

<p>I noticed the font display in gmail is completely different than the font displayed in my outlook, so I need to unify the font to ensure everyone reads it the same way whatever email client he is using.</p>