Font-size - CSS: Cascading Style Sheets - MDN Web Docs

Trang chủ » Html Td Style Font Size » Font-size - CSS: Cascading Style Sheets - MDN Web Docs

Có thể bạn quan tâm

Using an em value creates a dynamic or computed font size (historically the em unit was derived from the width of a capital "M" in a given typeface.). The numeric value acts as a multiplier of the font-size property of the element on which it is used. Consider this example:

cssp { font-size: 2em; }

In this case, the font size of <p> elements will be double the computed font-size inherited by <p> elements. By extension, a font-size of 1em equals the computed font-size of the element on which it is used.

If a font-size has not been set on any of the <p>'s ancestors, then 1em will equal the default browser font-size, which is usually 16px. So, by default 1em is equivalent to 16px, and 2em is equivalent to 32px. If you were to set a font-size of 20px on the <body> element say, then 1em on the <p> elements would instead be equivalent to 20px, and 2em would be equivalent to 40px.

In order to calculate the em equivalent for any pixel value required, you can use this formula:

em = desired element pixel value / parent element font-size in pixels

For example, suppose the font-size of the <body> of the page is set to 16px. If the font-size you want is 12px, then you should specify 0.75em (because 12/16 = 0.75). Similarly, if you want a font size of 10px, then specify 0.625em (10/16 = 0.625); for 22px, specify 1.375em (22/16).

The em is a very useful unit in CSS since it automatically adapts its length relative to the font that the reader chooses to use.

One important fact to keep in mind: em values compound. Take the following HTML and CSS:

csshtml { font-size: 100%; } span { font-size: 1.6em; } html<div> <span>Outer <span>inner</span> outer</span> </div>

The result is:

Assuming that the browser's default font-size is 16px, the words "outer" would be rendered at 25.6px, but the word "inner" would be rendered at 40.96px. This is because the inner <span>'s font-size is 1.6em which is relative to its parent's font-size, which is in turn relative to its parent's font-size. This is often called compounding.

Từ khóa » Html Td Style Font Size