關於block元素和inline元素

呃。。。這個會不會太基礎了。最近在複習，因此基礎知識也不可以忽略。

根據HTML 4.01 規範，其描述以下（http://www.w3.org/TR/html401/struct/global.html#h-7.5.3）：

1. 內容模型：block元素能夠包含block元素和inline元素，inline元素能夠包含數據和其餘inline元素（就是說inline不能包含block）。核心思想就是相比inline元素，block元素構建的結構都「比較大」。

2. 格式：默認，block元素之間有換行，inline元素之間沒有。

3. 文本方向：在實現文本方向上，block元素和inline元素有差異。block元素會繼承dir屬性，inline不會。

原文：

7.5.3 Block-level and inline elements

Certain HTML elements that may appear in BODY are said to be "block-level" while others are "inline" (also known as "text level"). The distinction is founded on several notions:

Content model

Generally, block-level elements may contain inline elements and other block-level elements. Generally, inline elements may contain only data and other inline elements. Inherent in this structural distinction is the idea that block elements create "larger" structures than inline elements.

Formatting

By default, block-level elements are formatted differently than inline elements. Generally, block-level elements begin on new lines, inline elements do not. For information about white space, line breaks, and block formatting, please consult the section on  text.

Directionality

For technical reasons involving the  [UNICODE] bidirectional text algorithm, block-level and inline elements differ in how they inherit directionality information. For details, see the section on  inheritance of text direction.

Style sheets provide the means to specify the rendering of arbitrary elements, including whether an element is rendered as block or inline. In some cases, such as an inline style for list elements, this may be appropriate, but generally speaking, authors are discouraged from overriding the conventional interpretation of HTML elements in this way.

The alteration of the traditional presentation idioms for block level and inline elements also has an impact on the bidirectional text algorithm. See the section on the effect of style sheets on bidirectionality for more information.