app/views/mailer/_mailer_header.html.erb
<table <%= placeholder_table_styles(width:'100%',style: "width:100%;min-width:100%") %>>
<tr>
<td>
<table <%= placeholder_table_styles %>>
<tr>
<td>
<table <%= placeholder_table_styles(width:'100%',style: "width:100%") %>>
<tr>
<td>
<span style="font-size: 24px; color: #333333;">
<%= user_salutation(user) %>
</span>
</td>
</tr>
<tr>
<%= placeholder_cell('8px', vertical: false) %>
</tr>
<% if local_assigns[:summary] %>
<tr>
<td>
<span style="font-size:16px; color: #1A67A3; font-weight: 600;">
<%= summary %>
</span>
</td>
</tr>
<% end %>
<tr>
<%= placeholder_cell('24px', vertical: false) %>
</tr>
<% if defined?(button_href) && defined?(button_text) %>
<tr>
<td>
<table <%= placeholder_table_styles %>>
<tr>
<td style="background: #D1E5F5; padding: 8px 12px; border: 1px solid #1A67A3; border-radius: 16px; overflow: hidden; text-overflow: ellipsis;">
<a href="<%= button_href %>"
target="_blank"
style="color: #1A67A3; text-decoration: none; font-size: 14px;">
<%= button_text %>
</a>
</td>
</tr>
</table>
</td>
</tr>
<% end %>
<% if local_assigns[:bottom_spacing] != false %>
<tr>
<%= placeholder_cell('16px', vertical: false) %>
</tr>
<% end %>
</table>
</td>
<%= placeholder_cell('16px', vertical: true) %>
</tr>
</table>
</td>
</tr>
</table>