有没有什么方法可以通过网页上的字符来改变文本的颜色?

One thing I've seen in some Desktop applications is the ability to change the color of text as the background changes -- to effectively have multiple colors on a single character. I've seen this most commonly with progress bars that display the percentage inside the bar. Generally a darker background color will be used as the progress bar color, and as it progresses, the dark color doesn't contrast enough with the dark text, so the text color changes as soon as the bar overlaps with the text. This image should explain what I mean:One thing I've seen in some Desktop application