Function: Creates the initial theme features when the ‘setup_theme’ action is fired.

Function: Registers a theme feature for use in add_theme_support().

Function: Gets the list of registered theme features.

Function: Gets the registration config for a theme feature.

Function: Validates the theme requirements for WordPress version and PHP version.

Function: Makes sure that auto-draft posts get their post_date bumped or status changed to draft to prevent premature garbage-collection.

Function: Filters changeset post data upon insert to ensure post_name is intact.

Function: Publishes a snapshot’s changes.

Function: Expands a theme’s starter content configuration using core-provided data.

Function: Updates the `custom_css` post for a given theme.

Function: Renders the Custom CSS style element.

Function: Fetches the `custom_css` post for a given theme.

Function: Fetches the saved Custom CSS content for rendering.

Function: Retrieves the markup for a custom header.

Function: Prints the markup for a custom header.

Function: Checks whether a header video is set or not.

Function: Retrieves header video URL for custom header.

Function: Displays header video URL.

Function: Retrieves header video settings.

Function: Checks whether a custom header is set or not.

Function: Checks whether the custom header video is eligible to show on the current page.

Function: Adds CSS to hide header text for custom logo, based on Customizer setting.

Function: Creates image tag markup for a custom header image.