Source

File: wp-includes/class-wp-customize-panel.php

protected function content_template() {
		?>
		<li class="panel-meta customize-info accordion-section <# if ( ! data.description ) { #> cannot-expand<# } #>">
			<button class="customize-panel-back" tabindex="-1"><span class="screen-reader-text"><?php _e( 'Back' ); ?></span></button>
			<div class="accordion-section-title">
				<span class="preview-notice">
				<?php
					/* translators: %s: The site/panel title in the Customizer. */
					printf( __( 'You are customizing %s' ), '<strong class="panel-title">{{ data.title }}</strong>' );
				?>
				</span>
				<# if ( data.description ) { #>
					<button type="button" class="customize-help-toggle dashicons dashicons-editor-help" aria-expanded="false"><span class="screen-reader-text"><?php _e( 'Help' ); ?></span></button>
				<# } #>
			</div>
			<# if ( data.description ) { #>
				<div class="description customize-panel-description">
					{{{ data.description }}}
				</div>
			<# } #>

			<div class="customize-control-notifications-container"></div>
		</li>
		<?php
	}