链接文字<a>保持原有的字体颜色

```css

```html
<span id="red"><a href="#">red</a></span>
<span id="blue"><a href="#">blue</a></span>
<span id="orange"><a href="#">orange</a></span>
<span id="green"><a href="#">green</a></span>

关键点代码：a {color: inherit;}
上述四行字最终显示颜色不变