By Joe Brock and Helen Nyambura-Mwaura JOHANNESBURG (Reuters) – When Michelle Obama and Beyonce Knowles attended high-profile events in clothes made by African designers, it was a sure sign that the continent’s vibrant style has arrived on the world stage. The showcasing of clothes from home-grown African designers in stores in New York, London and Tokyo is a sign of a broader change of attitude towards a continent which is earning a brighter reputation beyond stories of war and disease. It has proven difficult for Africa’s home grown designers to break into the mainstream fashion market because the perception has often been that products from the world’s poorest continent are of low quality or just not cool. Global fashion designers like Yves Saint Laurent took inspiration from Africa decades ago and more recently brands like Burberry, Louis Vuitton and Christian Dior have embraced the continent’s style and broadened its appeal.