Rem vs. Em: When Should You Use Each CSS Unit for Font Sizing?-CSS Tutorial-php.cn

Rem vs. Em: When Should You Use Each CSS Unit for Font Sizing?

Understanding the Difference Between Rem and Em in CSS

In web development, the choice between rem and em units for font sizing can impact the layout and responsiveness of your page. Let's explore how these units differ and their relative uses.

Rem vs. Em Units

Both rem and em units are relative units used to define font size or other properties in CSS. However, they differ in their relationship to their parent elements:

Em Units:

Relative to the font size of the parent element
A value of 1 em equals the current font size
Changes in the parent's font size also affect child elements with em values

Rem Units:

Relative to the base font size defined in the root (or specified by or elements)
A value of 1 rem equals the root font size
Changes in parent font sizes do not affect child elements with rem values

In the Provided Example:

In the code snippet you provided, the

element has a font-size of 1.4rem. This means that its font size is 1.4 times the base font size.

However, the

element within the

has a font-size of 1.4rem as well. Since

is a child element of

, if em units were used, the font size of

would be 1.4 times the font size of

, or 1.4 * 1.4 = 1.96 times the base font size.

Practical Considerations:

Rem units are recommended for consistent sizing across multiple levels of nested elements. They prevent cascading font size changes when intermediate containers alter their font size.
Em units are useful when you want to inherit the font size of a parent element but scale it slightly.
Both rem and em units allow for easier scaling of fonts when the browser window is resized, ensuring consistency in the layout.

The above is the detailed content of Rem vs. Em: When Should You Use Each CSS Unit for Font Sizing?. For more information, please follow other related articles on the PHP Chinese website!

source：php.cn

Previous article：How to Add Spacing Between Columns in Bootstrap Grid Layout? Next article：How to Add Elements to the Section with JavaScript When Facing CMS Restrictions?

Statement of this Website

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn