The returned value can be derived from the assumed character size and actual screen pixel size. 返回值可从设定的字符大小和实际屏幕像素大小推出。
Both attributes accept either a numeric value, indicating an absolute size in pixels, or a percentage, indicating the size as a percentage of the browser window height and width. 这两个属性的值可以是数字，表示绝对像素大小，也可以是百分比，表示相对于浏览器窗口高度和宽度的百分比大小。
