用渐变色填充背景。由浅及深的颜色给我们无尽的遐想，达到满意的视觉效果。在界面上点击鼠标左键，背景将以不同的渐变色填充。-filled with the background color gradient. From shallow and deep color to the endless daydream, to the satisfaction of the visual effects. Click on the interface with the left mouse button,