A vibrant and captivating t-shirt design featuring a playful unicorn prancing through a magical forest. The unicorn has a colorful mane and horn, and it's wearing a cute little hat with a sparkling gem. In the background, there's a beautiful rainbow stretching across the sky, and the forest is filled with whimsical trees and glowing mushrooms. The phrase 'Dream Big' is written in elegant, flowing script at the bottom of the design, inspiring a sense of wonder and imagination.