首先要定义一个基本字体系列和字体大小。
The first thing we did was to define a basic font family and font size.
需要使用一种便于大多数人阅读的基本字体大小。
A basic font size needs to be used that is readable for most people.
假设正文选择器的默认基本字体16px变为原来的62.5%，如清单4所示。
Assume the default base font of 16px has been reduced to 62.5% for the body selector, shown in Listing 4.
在本文中，我将展示根据对象在屏幕上的可见显示，为何em对于可设置的基本字体是相对的，而px对于基本字体是绝对的。
Within this article, I show how em is relative to the base font you can set, while px is absolute to the base font based on the visual display of an object on the screen.
在本文中，我将展示根据对象在屏幕上的可见显示，为何em对于可设置的基本字体是相对的，而px对于基本字体是绝对的。
Within this article, I show how em is relative to the base font you can set, while px is absolute to the base font based on the visual display of an object on the screen.
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