(Reuters) - European shares rose in thin trading on Monday, as optimism over reopening of countries and signs of more stimulus for the battered euro zone economy helped sentiment.The euro zone stock index rose 0.8% in early deals, with the pan-European STOXX 600 up 0.6% and Germany's DAX up 0.9%.Trading volumes were lower across the board with the U.S., UK and some countries in Asia closed for holidays.Germany's Bayer AG jumped 4.3% after saying it had made progress in seeking a settlement..