core-bundle/src/Resources/contao/dca/tl_style.php
public function updateAfterRestore($id, $table, $data)
	{
		if ($table != 'tl_style')
		{
			return;
		}

		// Update the timestamp of the style sheet
		$this->Database->prepare("UPDATE tl_style_sheet SET tstamp=? WHERE id=?")
					   ->execute(time(), $data['pid']);

		// Update the CSS file
		$this->import('Contao\StyleSheets', 'StyleSheets');
		$this->StyleSheets->updateStyleSheet($data['pid']);
	}
public function updateAfterRestore($id, $table, $data)
	{
		if ($table != 'tl_style')
		{
			return;
		}

		// Update the timestamp of the style sheet
		$this->Database->prepare("UPDATE tl_style_sheet SET tstamp=? WHERE id=?")
					   ->execute(time(), $data['pid']);

		// Update the CSS file
		$this->import('Contao\StyleSheets', 'StyleSheets');
		$this->StyleSheets->updateStyleSheet($data['pid']);
	}
Update a style sheet after a version has been restored

@param integer $id
@param string  $table
@param array   $data