app/views/mailer/_mailer_button.html.erb
<table <%= placeholder_table_styles(style: 'font-size:14px;') %>>
<tr>
<td>
<table <%= placeholder_table_styles(width: '100%', style: 'width:100%;') %>>
<tr>
<td>
</td>
</tr>
</table>
</td>
<%= placeholder_cell('10px', vertical: true) %>
<td>
<table <%= placeholder_table_styles %>>
<tr>
<td style="padding: 8px 12px; border: 1px solid #878787; border-radius: 16px; overflow: hidden; text-overflow: ellipsis;white-space: nowrap;">
<%= capture(&block) %>
</td>
</tr>
</table>
</td>
</tr>
</table>