title: How use style css in yii2-swiftmailer?
body: <p>How use style css in yii2-swiftmailer?</p>
  
  <p>I not know how use css style in yii2-swiftmailer. Css style  not add from css class <code>.button3</code>.</p>
  
  <p>I try:</p>
  
  <p>/controllers/SiteController</p>
  
  <pre><code>Yii::$app-&gt;mailer-&gt;compose('messager', ['testparams' =&gt; 'trtrtrtrt',])
   -&gt;setFrom('ergegergerger@gmail.com')
   -&gt;setTo('ergergergegerg@mail.ru')
   -&gt;setSubject('TEST')
   -&gt;send();
  </code></pre>
  
  <p>/mail/messager.php</p>
  
  <pre><code>&lt;?php
  use yii\helpers\Html;
  ?&gt;
  
  &lt;?= Html::encode($testparams) ?&gt;
  </code></pre>
  
  <p>/mail/layouts/html.php</p>
  
  <pre><code>&lt;?php
  use yii\helpers\Html;
  
  
  
  /* @var $this \yii\web\View view component instance */
  /* @var $message \yii\mail\MessageInterface the message being composed */
  /* @var $content string main view render result */
  ?&gt;
  &lt;?php $this-&gt;beginPage() ?&gt;
  &lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"&gt;
  &lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;
  &lt;head&gt;
      &lt;meta http-equiv="Content-Type" content="text/html; charset=&lt;?= Yii::$app-&gt;charset ?&gt;" /&gt;
  
      &lt;style type="text/css"&gt;
         .button3{
          background-color: green;
          width: 100px;
          height: 100px;
          }
      &lt;/style&gt;
      &lt;?php $this-&gt;head() ?&gt;
  
  &lt;/head&gt;
  &lt;body&gt;
      &lt;?php $this-&gt;beginBody() ?&gt;
  
  
      &lt;?= $content ?&gt;
  
      &lt;div class="button3"&gt;Приветик test !&lt;/div&gt;
  
  
      &lt;?php $this-&gt;endBody() ?&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  &lt;?php $this-&gt;endPage() ?&gt;
  </code></pre>