51  

Since you haven't specified any styles, the size of the headings is determined by your browser's default style sheet. In particular, this means that the relative size of the two headers may vary depending on the viewer's browser.

由于您尚未指定任何样式，标题的大小由浏览器的默认样式表决定。特别是，这意味着两个标题的相对大小可能根据观众的浏览器而变化。

Looking at your fiddle in Chrome 33, I do see the effect you describe. Right-clicking the headings and selecting "Inspect element" reveals that the issue is cause by the presence of the

In particular, Chrome's default style sheet normally includes the rules:

特别是，Chrome的默认样式表通常包含以下规则：

h1 { font-size: 2em }

and:

和：

h2 { font-size: 1.5em }

However, the former rule is overridden inside

:-webkit-any(article,aside,nav,section) h1 {
    font-size: 1.5em;
}

:-webkit-any(article,aside,nav,section)
:-webkit-any(article,aside,nav,section) h1 {
    font-size: 1.17em;
}

27  

It is because of documentation style requirements. You can find details at HTML 5.1 documentation @ 10.3.7 Sections and headings