Child Themes

Child themes provide an easy way to add custom assets, override template files or extend YOOtheme Pro with more functionality. All customizations are preserved during updates of YOOtheme Pro.

A child theme is used to make modifications to any part of YOOtheme Pro. It has its own theme directory next to the yootheme directory. This way customizations are separated from YOOtheme Pro which makes them portable, replicable and unaffected by YOOtheme Pro theme updates. Typically, a child theme is used for the following customizations.

  • To add JavaScript, CSS and fonts
  • To add Less styles to the style library
  • To override templates files
  • To add builder elements to the element library
  • To extend YOOtheme Pro with custom PHP code

Note YOOtheme Pro provides custom code settings where you can add custom JavaScript, CSS or Less. This may be sufficient for smaller customizations without the need to create a child theme. They can be found in the Settings → Custom Code panel of YOOtheme Pro. Additionally, each page builder element has an option to apply custom CSS in the Advanced tab of the element settings.

Create a Child Theme

Open the Joomla template directory templates and create a new folder yootheme_NAME for the child theme. The suffix is the name of the child theme, for example yootheme_mytheme.

Once the directory is created, the child theme can be activated in the Settings → Advanced panel of YOOtheme Pro. Just select the child theme, click Save and refresh the browser window.

Activate Joomla child theme

Note A YOOtheme Pro child theme does not have its own settings. You can enable or disable the child theme, but the theme settings will stay the same. To have different settings, create a new template style in Joomla and select the child theme there.

JavaScript, CSS and Fonts

To quickly load additional JavaScript or CSS in a child theme, create a js or css directory with a respective custom.js or custom.css file. These files are automatically loaded by YOOtheme Pro. To load specific JavaScript or CSS files take a look at the modules documentation.


To load a custom font, create a fonts directory with all the needed font files. Add a @font-face at-rule to the css/custom.css file and specify the font resources.

@font-face {
    font-family: "Custom Font";
    src: url("../fonts/custom-font.woff2") format("woff2");

The font Custom Font can now be used in CSS. To set the font in the style customizer, open the font picker and instead of selecting one of the proposed fonts, type in the name Custom Font into the search field and hit the Enter key.

Set a custom font in the style customizer

Note There is no need to add a custom font manually in the child theme if it is already available in the style customizer. This is because when a Google font is selected in the style customizer, it's automatically downloaded to the web server and stored locally. There is no round-trip to the Google Fonts server, which is great for page speed and GDPR-compliance.

Less Styles

Styles in YOOtheme Pro are built with the UIkit framework. They are written in Less and customizable through the style customizer.

To add a custom style to the style library, create a less directory in the child theme and add a file theme.NAME.less. The suffix is the name of the style, for example Once the file is created, the style My Style can be selected in the style library.

Add a header comment with additional information at the very top of the file.


Name: My Style
Background: White
Color: Black
Type: Flat

Property Description
name Optional name which will be used instead of the file name in the style library
background Value for the Background Color filter in the style library
color Value for the Primary Color filter in the style library
type Value for the Style Type filter in the style library
preview Path to the image used in the style library

Now either modify an existing style or one of its variations, or start from scratch. Just import the necessary Less files and add your customizations. Learn more about overwriting Less variables, extending existing CSS rules by using mixins or adding your own CSS rules in the UIkit themes documentation.

Modify a Style

The easiest way to create a custom style is to customize an existing one. Just import a style into the Less file and add your customizations.

// Import a style, for example `Fuse`
@import "../../yootheme/less/theme.fuse.less";

// Add custom Less code here

All available styles can be found in the less directory in YOOtheme Pro.

Modify a Style Variation

Each style has different variations. To start with one of them, just import the style and its variation.

// Import a style, for example `Fuse`
@import "../../yootheme/less/theme.fuse.less";

// Import a style variation, for example `dark-yellow`
@import "../../yootheme/vendor/assets/uikit-themes/master-fuse/styles/dark-yellow.less";

// Add custom Less code here

All style variations can be found in the corresponding style vendor/assets/uikit-themes/master-NAME/styles directory in YOOtheme Pro.

Import Texture Images

Some styles use texture images to decorate section overlaps or element borders. To use these textures from the original LESS style they need to be imported. Add a file config.php to the child theme directory and import the images.

return [
    'theme' => [
        'styles' => [
            'imports' => [
                'textures' => \YOOtheme\Path::get('../yootheme/vendor/assets/uikit-themes/master-pinewood-lake/images/*.svg'),

Start from Scratch

To create a style from scratch, all necessary files need to be imported separately. This includes platform and theme specific styles, the UIkit framework and the Master UIkit Theme.

// Import platform specific styles for Wordpress or Joomla
@import "../../yootheme/less/platform.less";

// Import the UIkit framework
@import "../../yootheme/vendor/assets/uikit/src/less/uikit.less";

// Import the `Master` UIkit theme. It extends UIkit with variables and mixins for YOOtheme Pro.
@import "../../yootheme/vendor/assets/uikit-themes/master/_import.less";

// Import YOOtheme Pro theme specific styles
@import "../../yootheme/less/theme.less";

// Add custom Less code here

Template Files

Template files, for example the index, header, menu or module templates can easily be customized. Simply add a template file to the child theme, and it will override the exact same file in YOOtheme Pro. It’s recommended to copy the original file from YOOtheme Pro to the child theme and start modifications from there.

Any Joomla template file can be included in the child theme, not just the ones from YOOtheme Pro. Learn more about how to override the different template files in the Joomla understanding output overrides documentation.

Here is an overview of all template files in YOOtheme Pro.

Theme Templates

The following template files serve as entry points to the Joomla site.

Template Description
index.php The main template file which renders the actual theme layout
error.php Render error pages.
offline.php Render the offline page.
component.php Render the component output only.

Output Overrides

YOOtheme Pro overrides com_content, com_finder, com_search and com_tags template files as well as most modules. The template files are located in the html directory of YOOtheme Pro. To override one of them or other Joomla components, add the respective template files to the html directory of the child theme.

Since Joomla only has articles and does not differentiate between a single page or a blog post, YOOtheme Pro uses template partials across all component overrides to render articles differently. A simple template hierarchy determines which template partial is loaded.

Template Partial Description
templates/article.php Render articles if no other matching template file is found.
templates/article-blog.php Render categorized articles which are used as posts. Included in com_content/category and com_content/article.
templates/article-page.php Render uncategorized articles which are used as pages. Included in com_content/article.
templates/article-search.php Render results on search pages. Included in com_finder and com_search.
templates/article-featured.php Render featured articles. Included in com_content/featured.
templates/article-tag.php Render tagged articles. Included in com_content/tag.
templates/meta.php Render the meta information. Included in all article templates.

Note There are two edge cases when overriding template file using a YOOtheme Pro child theme doesn't work.

  1. Native Joomla modules can be overridden but for third-party modules this applies only if they use JModuleHelper::getLayoutPath and the layout parameter.
  2. Template files from html/plg_PLUGIN and html/layouts can only be overridden in a child theme if there is already an override in YOOtheme Pro.

In both cases, put the template overrides in the html directory of YOOtheme Pro. They won't be overridden when updating YOOtheme Pro.

Section Templates

The following template files render the different sections.

Template Description
templates/section.php Render the section for the top and bottom positions.
templates/sidebar.php Render the sidebar for the sidebar position.

Header Templates

The following template files render the different header layouts.

Template Description
templates/header.php Render the header and its navigation.

The following template partials are included by the header.php.

Template Partial Description
templates/toolbar.php Render the toolbar.
templates/header-mobile.php Render the mobile header and its navigation.
templates/header-logo.php Render the logo.
templates/search.php Render the search toggle and field.
templates/socials.php Render the social icons.

Module and Position Templates

The following template files render the module position layouts.

Template Description
templates/position.php Render the position.
templates/module.php Render the module.

The following template files render the different menus.

Template Description
templates/menu/menu.php Render the menu.
templates/menu/nav.php Render menu items for the vertical nav.
templates/menu/navbar.php Render menu items for the navbar.
templates/menu/subnav.php Render menu items for the subnav.
templates/breadcrumbs.php Render the breadcrumb navigation.
templates/pagination.php Render the pagination.

Builder Elements

To add a custom element to the page builder, create a builder directory in the child theme and copy the custom element into it. It will be loaded automatically by YOOtheme Pro and will be available in the element library. For more information on how to create a custom element read the elements documentation.

Extend Functionality

To extend YOOtheme Pro with custom functionalities, add a file config.php which returns an array with a module definition to the child theme directory. It will be loaded automatically by YOOtheme Pro. For more information read the modules documentation.


return [

    // Module definition


To organize extensive customization in multiple modules, their module definitions can be loaded in the config.php file using the $app->load method. For example, create a modules directory that will contain all modules each with its own directory.


$app->load(__DIR__ . '/modules/*/bootstrap.php');

return [];

Module Positions

Joomla allows creating module positions on the fly. There is no need to add them using the child theme. Simply type in a custom position name instead of selecting an existing one when creating a new module. Once a module is assigned to the new position, it will be available in the dropdown for other modules as well.

Create module position

YOOtheme Pro Documentation