On mac (Chrome and Safari), words look bolder than on PC, why?

问题

When reviewing on different OS's, I noticed that particularly in Chrome and Safari, words on a mac book look bolder than on a PC. Isn't it true that only browser web-kits have the capability of interpreting CSS and HTML, not an OS itself?

Here is my CSS for the anchor tags (words) if the above case isn't valid:

.homeText .cases {
    color: #bcbcbc;
    float:left;
    font-family:Arial, Helvetica Neue, Sans-Serif;
    font-size: 2.65em;
    font-weight:bolder;
    line-height: 30px;
    height:30px;
    margin: 0px;
    margin-right: -2px;
    padding-right: 13px;
    position: absolute;
}

回答1:

If I'm not mistaken, this is due to differences in the text-rendering algorithms used by each OS. This article provides a detailed explanation with examples for comparison.

回答2:

OS X isn't changing the CSS or boldness of the text. It uses different font rendering and smoothing algorithms for displaying text, so text usually appears "fatter" on OS X than on Windows. Here's one site that talks about it. Googling "OS X font smoothing" will give you lots of results.

来源：https://stackoverflow.com/questions/9874303/on-mac-chrome-and-safari-words-look-bolder-than-on-pc-why