function wp_get_block_css_selector( $block_type, $target = 'root', $fallback = false ) {
  if ( empty( $target ) ) {
    return null;
  }

  $has_selectors = ! empty( $block_type->selectors );

  // Root Selector.

  // Calculated before returning as it can be used as fallback for
  // feature selectors later on.
  $root_selector = null;

  if ( $has_selectors && isset( $block_type->selectors['root'] ) ) {
    // Use the selectors API if available.
    $root_selector = $block_type->selectors['root'];
  } elseif ( isset( $block_type->supports['__experimentalSelector'] ) && is_string( $block_type->supports['__experimentalSelector'] ) ) {
    // Use the old experimental selector supports property if set.
    $root_selector = $block_type->supports['__experimentalSelector'];
  } else {
    // If no root selector found, generate default block class selector.
    $block_name    = str_replace( '/', '-', str_replace( 'core/', '', $block_type->name ) );
    $root_selector = ".wp-block-{$block_name}";
  }

  // Return selector if it's the root target we are looking for.
  if ( 'root' === $target ) {
    return $root_selector;
  }

  // If target is not `root` we have a feature or subfeature as the target.
  // If the target is a string convert to an array.
  if ( is_string( $target ) ) {
    $target = explode( '.', $target );
  }

  // Feature Selectors ( May fallback to root selector ).
  if ( 1 === count( $target ) ) {
    $fallback_selector = $fallback ? $root_selector : null;

    // Prefer the selectors API if available.
    if ( $has_selectors ) {
      // Look for selector under `feature.root`.
      $path             = array( current( $target ), 'root' );
      $feature_selector = _wp_array_get( $block_type->selectors, $path, null );

      if ( $feature_selector ) {
        return $feature_selector;
      }

      // Check if feature selector is set via shorthand.
      $feature_selector = _wp_array_get( $block_type->selectors, $target, null );

      return is_string( $feature_selector ) ? $feature_selector : $fallback_selector;
    }

    // Try getting old experimental supports selector value.
    $path             = array( current( $target ), '__experimentalSelector' );
    $feature_selector = _wp_array_get( $block_type->supports, $path, null );

    // Nothing to work with, provide fallback or null.
    if ( null === $feature_selector ) {
      return $fallback_selector;
    }

    // Scope the feature selector by the block's root selector.
    return WP_Theme_JSON::scope_selector( $root_selector, $feature_selector );
  }

  // Subfeature selector
  // This may fallback either to parent feature or root selector.
  $subfeature_selector = null;

  // Use selectors API if available.
  if ( $has_selectors ) {
    $subfeature_selector = _wp_array_get( $block_type->selectors, $target, null );
  }

  // Only return if we have a subfeature selector.
  if ( $subfeature_selector ) {
    return $subfeature_selector;
  }

  // To this point we don't have a subfeature selector. If a fallback
  // has been requested, remove subfeature from target path and return
  // results of a call for the parent feature's selector.
  if ( $fallback ) {
    return wp_get_block_css_selector( $block_type, $target[0], $fallback );
  }

  return null;
}