"Design a sophisticated and vivid gift voucher for Pien de Groot's birthday, inviting her to experience indoor skydiving in Utrecht. Visualize a background that simulates the breathtaking sensation of flying, with bright and inspiring colors that radiate excitement and adventure. Incorporate elements typical of indoor skydiving, such as a wind tunnel, figures flying in the air, and gear like helmets and flight suits, to highlight the essence of the experience. Ensure the text 'Happy Birthday Pien de Groot! An adventure awaits you in Utrecht - Indoor Skydiving' is prominently displayed in an inviting font. The style should be modern and energetic, with a touch of elegance to emphasize the special nature of this gift. Remember to leave space for a personal message and the details of the gift voucher, like the expiry date and signature.  --s 750