This is an example of a custom layout with two parts left_sidebar and sidebar. Custom layouts can be used for creating landing pages or custom styles for Redmine pages
<!DOCTYPE html>
<html lang="{{page.locale}}">
<head>
{{ 'main_styles' | stylesheet_page_tag: 'type:text/css' }} <!-- page with name main_styles will be included as css file => <link href="/pages/stylesheets/main_styles.css?20170703073152" type="text/css" rel="stylesheet"> -->
</head>
<body>
{% if_part_content 'left_sidebar' %}
<div id="left_sidebar">
{% part_content 'left_sidebar' %} <!--current page part called "left_sidebar" will be rendered here if existed -->
</div>
{% endif_part_content %}
<div id="content">
{% content %} <!-- current page content will be rendered here if existed or Redmine page content -->
</div>
<div id="sidebar">
{% part_content 'sidebar' %} <!-- current page part called "sidebar" will be rendered here or Redmine page Sidebar content -->
</div>
</body>
</html>