Once you've got your file in order, you just need to pass the rem-calc() function where you want to output the pixel values ​​in rem. This is necessary if you want to perform any arithmetic operation on any value, which we will do later in the rem() function.

For example, given a px value divided by the base, we can convert a percentage of px to rem by multiplying it by 1rem. To get the transformation, the best way to take advantage of SASS functions is to create a function that calculates REM value values ​​given the base font size. Luckily, it's really easy to convert any value to rem with Sass, and we can get it in three ways or methods using mixins and functions.

First step, we need to write a Sass function that gets the rem value based on the passed px value. Ever since we started using Sass for our projects, for convenience we have written a mixin that convertspx to rem converter. As in the previous case, we can simplify the code if you want to use a combination of rem and em in your code.

Using web and rem components works just like normal HTML and CSS; however, the rem value may be disabled if the component comes with a different base font than using the app. You may have been using em and rem CSS units for a while, but the difference between the two still seems unclear. So let's write a simple component (header element) using rem or em and you'll see how these two rules work. This means that if the base font size on the page changes, anything that uses rem will be scaled relative to that font size.

Using rem units, you can easily scale everything up or down by simply resizing the root element. The beauty is that by using rem units to define font size, you as a designer maintain the harmony and scale hierarchy of your type, while still providing flexibility for users who need to adjust font size. The font size set by the user in the browser can affect the value when the rem CSS module is used in a web application.

When using custom browser settings to set em or rem font values ​​for html elements, the calculated pixel value will be a multiple of the browser font size setting for the specified font size. By default, the base pixel value used to calculate the rem value is taken from the $global-font-size variable.

REM is not converted to px per se, but you can calculate the px value based on your main font size. This script will convert each px value to rem from the selected properties to allow the browser to set the font size.

Functions are a good candidate for converting pixel values ​​to rem, since many websites use rem not only to set the font size, but also for other block properties. Using CSS Custom Properties and CSS Calc, we can create dynamic rem values ​​but express them as px variables.