CSS实验:linear-gradient 实现「四角边框」和「 字体渐变」background: linear-gradient(red, yellow, blue); background: linear-gradient(red 0%, yellow 50%, blue 100%); background: linear-gradient(to right, red 0%, yellow 50%, blue 100%); background: linear-gradient(90deg, red 0%, yellow 50%, blue 100%);