莫道桑榆晚为霞尚满天--刘禹锡 “莫道桑榆晚 为霞尚满天”中“为霞” 的具体意思是什么？

刘禹锡的 don't think it's late when the sun looks just above the treetops，since sunshine can still light up the sky好吧…百…我承认度...