The role of html tag

em is the abbreviation of Emphasis (emphasis). Text contained within ~ will be highlighted. Browsers such as Internet Explorer will display text in italics, and some browsers will use other methods such as changing the color of the text to achieve an emphasis effect. The

em> tag (html em emphasis tag) tells the browser to represent the text within it as emphasized content. For all browsers, this means that this text should be presented in italics for everyone to display. This has the same effect as the HTML I italic tag.

1) The contents modified by tags are displayed in italics, but these contents also have a broader meaning. If you only want to use italics to display text, please use < ;i> tag. In addition, documents can also include cascading style definitions that change the display of text.

2), em defines the content emphasis function

3), the default italic special style of the EM tag can be initialized using CSS styles, we will introduce how to determine the em emphasis tag’s own in a later article style.

em has the following characteristics:

1. The value of em is not fixed;
2. em will inherit the font size of the parent element.

So when we write CSS, we need to pay attention to two points:

1. Declare

Font-size=62.5%; in the body selector 2. Divide your original px value by 10, and then change to em as the unit;
　3. Recalculate the em value of the enlarged fonts. Avoid repeated declarations of font sizes.

That is to avoid the phenomenon of 1.2 * 1.2= 1.44. For example, if you declare the font size to be 1.2em in #content, then when you declare the font size of p, it can only be 1em, not 1.2em, because this em is not that em, and it inherits the font height of #content. It became 1em=12px.

However, the exception is 12px Chinese characters. The 12px (1.2em) Chinese characters obtained by the above method are not equal to the font size directly defined by 12px in IE, but are slightly larger. This problem has been solved by Jorux. Just change 62.5% to 63% in the body selector and it will display normally. The reason may be that when IE processes Chinese characters, the accuracy of floating point values ​​is limited.

em is a relative length unit. The font size relative to the text within the current

object. If the current font size for inline text has not been manually set, it will be relative to the browser's default font size.

The default font height of any browser is 16px. All unmodified browsers conform to: 1em=16px. Then 12px=0.75em,10px=0.625em. In order to simplify the conversion of font-size, you need to declare Font-size=62.5% in the body selector in CSS, which makes the em value become 16px*62.5%=10px, so 12px=1.2em, 10px=1em, also That is to say, you only need to divide your original px value by 10, and then change to em as the unit.

Ask a few questions:

1. What is tag?

2. What is the difference between tag and tag?

The first question is the most perverted:

The most honest answer: I don’t know, I haven’t seen it at all!

The most confusing answer: Big brother, em is the length unit, it is css, not the

html tag, it is the same unit as px (pixel).

The most awesome answer: em? It's just for emphasis, italics, but it's not recommended. You can see that most major websites don't use this tag.

The second question is mainly about introducing html semantics. Although both are displayed in italics in the browser, is a semantic tag, which means that it is not only It is italic, and more importantly, it has a specific meaning. is an expressive tag, which just expresses italics;

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