o pixel values by default.
	if ( is_numeric( $raw_value ) ) {
		$raw_value = $raw_value . 'px';
	}

	$defaults = array(
		'coerce_to'        => '',
		'root_size_value'  => 16,
		'acceptable_units' => array( 'rem', 'px', 'em' ),
	);

	$options = wp_parse_args( $options, $defaults );

	$acceptable_units_group = implode( '|', $options['acceptable_units'] );
	$pattern                = '/^(\d*\.?\d+)(' . $acceptable_units_group . '){1,1}$/';

	preg_match( $pattern, $raw_value, $matches );

	// Bails out if not a number value and a px or rem unit.
	if ( ! isset( $matches[1] ) || ! isset( $matches[2] ) ) {
		return null;
	}

	$value = $matches[1];
	$unit  = $matches[2];

	/*
	 * Default browser font size. Later, possibly could inject some JS to
	 * compute this `getComputedStyle( document.querySelector( "html" ) ).fontSize`.
	 */
	if ( 'px' === $options['coerce_to'] && ( 'em' === $unit || 'rem' === $unit ) ) {
		$value = $value * $options['root_size_value'];
		$unit  = $options['coerce_to'];
	}

	if ( 'px' === $unit && ( 'em' === $options['coerce_to'] || 'rem' === $options['coerce_to'] ) ) {
		$value = $value / $options['root_size_value'];
		$unit  = $options['coerce_to'];
	}

	/*
	 * No calculation is required if swapping between em and rem yet,
	 * since we assume a root size value. Later we might like to differentiate between
	 * :root font size (rem) and parent element font size (em) relativity.
	 */
	if ( ( 'em' === $options['coerce_to'] || 'rem' === $options['coerce_to'] ) && ( 'em' === $unit || 'rem' === $unit ) ) {
		$unit = $options['coerce_to'];
	}

	return array(
		'value' => round( $value, 3 ),
		'unit'  => $unit,
	);
}

/**
 * Internal implementation of CSS clamp() based on available min/max viewport
 * width and min/max font sizes.
 *
 * @since 6.1.0
 * @access private
 *
 * @param array $args {
 *     Optional. An associative array of values to calculate a fluid formula
 *     for font size. Default is empty array.
 *
 *     @type string $maximum_viewport_width Maximum size up to which type will have fluidity.
 *     @type string $minimum_viewport_width Minimum viewport size from which type will have fluidity.
 *     @type string $maximum_font_size      Maximum font size for any clamp() calculation.
 *     @type string $minimum_font_size      Minimum font size for any clamp() calculation.
 *     @type int    $scale_factor           A scale factor to determine how fast a font scales within boundaries.
 * }
 * @return string|null A font-size value using clamp() on success, otherwise null.
 */
function wp_get_computed_fluid_typography_value( $args = array() ) {
	$maximum_viewport_width_raw = isset( $args['maximum_viewport_width'] ) ? $args['maximum_viewport_width'] : null;
	$minimum_viewport_width_raw = isset( $args['minimum_viewport_width'] ) ? $args['minimum_viewport_width'] : null;
	$maximum_font_size_raw      = isset( $args['maximum_font_size'] ) ? $args['maximum_font_size'] : null;
	$minimum_font_size_raw      = isset( $args['minimum_font_size'] ) ? $args['minimum_font_size'] : null;
	$scale_factor               = isset( $args['scale_factor'] ) ? $args['scale_factor'] : null;

	// Normalizes the minimum font size in order to use the value for calculations.
	$minimum_font_size = wp_get_typography_value_and_unit( $minimum_font_size_raw );

	/*
	 * We get a 'preferred' unit to keep units consistent when calculating,
	 * otherwise the result will not be accurate.
	 */
	$font_size_unit = isset( $minimum_font_size['unit'] ) ? $minimum_font_size['unit'] : 'rem';

	// Normalizes the maximum font size in order to use the value for calculations.
	$maximum_font_size = wp_get_typography_value_and_unit(
		$maximum_font_size_raw,
		array(
			'coerce_to' => $font_size_unit,
		)
	);

	// Checks for mandatory min and max sizes, and protects against unsupported units.
	if ( ! $maximum_font_size || ! $minimum_font_size ) {
		return null;
	}

	// Uses rem for accessible fluid target font scaling.
	$minimum_font_size_rem = wp_get_typography_value_and_unit(
		$minimum_font_size_raw,
		array(
			'coerce_to' => 'rem',
		)
	);

	// Viewport widths defined for fluid typography. Normalize units.
	$maximum_viewport_width = wp_get_typography_value_and_unit(
		$maximum_viewport_width_raw,
		array(
			'coerce_to' => $font_size_unit,
		)
	);
	$minimum_viewport_width = wp_get_typography_value_and_unit(
		$minimum_viewport_width_raw,
		array(
			'coerce_to' => $font_size_unit,
		)
	);

	/*
	 * Build CSS rule.
	 * Borrowed from https://websemantics.uk/tools/responsive-font-calculator/.
	 */
	$view_port_width_offset = round( $minimum_viewport_width['value'] / 100, 3 ) . $font_size_unit;
	$linear_factor          = 100 * ( ( $maximum_font_size['value'] - $minimum_font_size['value'] ) / ( $maximum_viewport_width['value'] - $minimum_viewport_width['value'] ) );
	$linear_factor_scaled   = round( $linear_factor * $scale_factor, 3 );
	$linear_factor_scaled   = empty( $linear_factor_scaled ) ? 1 : $linear_factor_scaled;
	$fluid_target_font_size = implode( '', $minimum_font_size_rem ) . " + ((1vw - $view_port_width_offset) * $linear_factor_scaled)";

	return "clamp($minimum_font_size_raw, $fluid_target_font_size, $maximum_font_size_raw)";
}

/**
 * Returns a font-size value based on a given font-size preset.
 * Takes into account fluid typography parameters and attempts to return a CSS
 * formula depending on available, valid values.
 *
 * @since 6.1.0
 * @since 6.1.1 Adjusted rules for min and max font sizes.
 *
 * @param array $preset                     {
 *     Required. fontSizes preset value as seen in theme.json.
 *
 *     @type string           $name Name of the font size preset.
 *     @type string           $slug Kebab-case, unique identifier for the font size preset.
 *     @type string|int|float $size CSS font-size value, including units if applicable.
 * }
 * @param bool  $should_use_fluid_typography An override to switch fluid typography "on". Can be used for unit testing.
 *                                           Default is false.
 * @return string|null Font-size value or null if a size is not passed in $preset.
 */
function wp_get_typography_font_size_value( $preset, $should_use_fluid_typography = false ) {
	if ( ! isset( $preset['size'] ) ) {
		return null;
	}

	/*
	 * Catches empty values and 0/'0'.
	 * Fluid calculations cannot be performed on 0.
	 */
	if ( empty( $preset['size'] ) ) {
		return $preset['size'];
	}

	// Checks if fluid font sizes are activated.
	$typography_settings         = wp_get_global_settings( array( 'typography' ) );
	$should_use_fluid_typography = isset( $typography_settings['fluid'] ) && true === $typography_settings['fluid'] ? true : $should_use_fluid_typography;

	if ( ! $should_use_fluid_typography ) {
		return $preset['size'];
	}

	// Defaults.
	$default_maximum_viewport_width   = '1600px';
	$default_minimum_viewport_width   = '768px';
	$default_minimum_font_size_factor = 0.75;
	$default_scale_factor             = 1;
	$default_minimum_font_size_limit  = '14px';

	// Font sizes.
	$fluid_font_size_settings = isset( $preset['fluid'] ) ? $preset['fluid'] : null;

	// A font size has explicitly bypassed fluid calculations.
	if ( false === $fluid_font_size_settings ) {
		return $preset['size'];
	}

	// Try to grab explicit min and max fluid font sizes.
	$minimum_font_size_raw = isset( $fluid_font_size_settings['min'] ) ? $fluid_font_size_settings['min'] : null;
	$maximum_font_size_raw = isset( $fluid_font_size_settings['max'] ) ? $fluid_font_size_settings['max'] : null;

	// Font sizes.
	$preferred_size = wp_get_typography_value_and_unit( $preset['size'] );

	// Protects against unsupported units.
	if ( empty( $preferred_size['unit'] ) ) {
		return $preset['size'];
	}

	/*
	 * Normalizes the minimum font size limit according to the incoming unit,
	 * in order to perform comparative checks.
	 */
	$minimum_font_size_limit = wp_get_typography_value_and_unit(
		$default_minimum_font_size_limit,
		array(
			'coerce_to' => $preferred_size['unit'],
		)
	);

	// Don't enforce minimum font size if a font size has explicitly set a min and max value.
	if ( ! empty( $minimum_font_size_limit ) && ( ! $minimum_font_size_raw && ! $maximum_font_size_raw ) ) {
		/*
		 * If a minimum size was not passed to this function
		 * and the user-defined font size is lower than $minimum_font_size_limit,
		 * do not calculate a fluid value.
		 */
		if ( $preferred_size['value'] <= $minimum_font_size_limit['value'] ) {
			return $preset['size'];
		}
	}

	// If no fluid max font size is available use the incoming value.
	if ( ! $maximum_font_size_raw ) {
		$maximum_font_size_raw = $preferred_size['value'] . $preferred_size['unit'];
	}

	/*
	 * If no minimumFontSize is provided, create one using
	 * the given font size multiplied by the min font size scale factor.
	 */
	if ( ! $minimum_font_size_raw ) {
		$calculated_minimum_font_size = round(
			$preferred_size['value'] * $default_minimum_font_size_factor,
			3
		);

		// Only use calculated min font size if it's > $minimum_font_size_limit value.
		if ( ! empty( $minimum_font_size_limit ) && $calculated_minimum_font_size <= $minimum_font_size_limit['value'] ) {
			$minimum_font_size_raw = $minimum_font_size_limit['value'] . $minimum_font_size_limit['unit'];
		} else {
			$minimum_font_size_raw = $calculated_minimum_font_size . $preferred_size['unit'];
		}
	}

	$fluid_font_size_value = wp_get_computed_fluid_typography_value(
		array(
			'minimum_viewport_width' => $default_minimum_viewport_width,
			'maximum_viewport_width' => $default_maximum_viewport_width,
			'minimum_font_size'      => $minimum_font_size_raw,
			'maximum_font_size'      => $maximum_font_size_raw,
			'scale_factor'           => $default_scale_factor,
		)
	);

	if ( ! empty( $fluid_font_size_value ) ) {
		return $fluid_font_size_value;
	}

	return $preset['size'];
}

// Register the block support.
WP_Block_Supports::get_instance()->register(
	'typography',
	array(
		'register_attribute' => 'wp_register_typography_support',
		'apply'              => 'wp_apply_typography_support',
	)
);