postcss-rem-to-rem-multiplier 

A plugin for PostCSS that multiplies rem with a multiplier to ajust for diffrent root font-size.

Install

``shell
$ npm install postcss-rem-to-rem-multiplier --save-dev
`

Usage

Sometimes you need to include a css file that uses rems. Great pracitice! Unless you can't afford to change your body font-size just for some one css.

This script converts every rem value to a ajusted rem value from the properties you choose using a multiplier of default 0.625.

$3

With the default settings, only font related properties are targeted.

`css
// input
h1 {
margin: 0 0 20px;
font-size: 2rem;
line-height: 1.2;
letter-spacing: 0.0625rem;
}

// output
h1 {
margin: 0 0 20px;
font-size: 1.25rem;
line-height: 1.2;
letter-spacing: 1px;
}
`

$3

`js
var fs = require('fs');
var postcss = require('postcss');
var remToPx = require('postcss-rem-to-rem-multiplier');
var css = fs.readFileSync('main.css', 'utf8');
var options = {};
var processedCss = postcss(remToPx(options)).process(css).css;

fs.writeFile('main-px.css', processedCss, function (err) {
if (err) {
throw err;
}
console.log('Rem file written.');
});
`

$3

Type: Object | Null
Default:
`js
{
multiplier: 0.625,
unitPrecision: 5,
selectorBlackList: [],
propList: ['font', 'font-size', 'line-height', 'letter-spacing'],
mediaQuery: false,
multiplierCssVarName: null
}
`

- multiplier (Number) The multiplier by which to change the rem values default: (10/16) = 0.625.
- Calculate the multiplier e.g. the given css is written for font-size: 16px (default browser font size), your page uses 10px font size. 10/16 = 0.625
- unitPrecision (Number) The decimal precision px units are allowed to use, floored (rounding down on half).
- propList (Array) The properties that can change from rem to px.
- Values need to be exact matches.
- Use wildcard to enable all properties. Example: ['']
- Use at the start or end of a word. (['position*'] will match background-position-y)
- Use ! to not match a property. Example: ['*', '!letter-spacing']
- Combine the "not" prefix with the other prefixes. Example: ['', '!font']
- selectorBlackList (Array) The selectors to ignore and leave as rem.
- If value is string, it checks to see if selector contains the string.
- ['body'] will match .body-class
- If value is regexp, it checks to see if the selector matches the regexp.
- [/^body$/] will match body but not .body
- mediaQuery (Boolean) Allow rem to be converted in media queries.
- minRemValue (Number) Set the minimum rem value to replace.
- multiplierCssVarName (String | Null) replaces multiplier with a css variable , the comupting to ajusted rem value then happends runtime in the browser.
- syntax use for runtime computation calc( * var())

$3

`js
var gulp = require('gulp');
var postcss = require('gulp-postcss');
var autoprefixer = require('autoprefixer');
var remToPx = require('postcss-rem-to-rem-multiplier');

gulp.task('css', function () {

var processors = [
autoprefixer({
browsers: 'last 1 version'
}),
remToPx()
];

return gulp.src(['build/css/*/.css'])
.pipe(postcss(processors))
.pipe(gulp.dest('build/css'));
});
`

$3

`css
// rem is converted to rem with a multiplier
.convert {
font-size: 1rem; // converted to 0.625rem
}

// Rem or REM is ignored by postcss-rem-to-rem-multiplier but still accepted by browsers
.ignore {
border: 1Rem solid; // ignored
border-width: 2REM; // ignored
}
`

$3

`js
{
plugins: [
[
'postcss-rem-to-rem-multiplier', // ajust the rem vlaues used in canopy for 10px root font size to 10 px root font size in monoliht
{
multiplierCssVarName: '--r2r-multi',
propList: ['*']
}
]
]
}
`

`css
// source
.convert {
font-size: 1rem; // converted to calc(0.625rem
}
`

`css
// output
.convert {
font-size: calc(1rem * var(--r2r-multi); // converted to calc(0.625rem
}
``

Credits

This repository is mainly based on the work from https://github.com/jesstech/postcss-rem-to-pixel.
The change is that it does not convert from rem to px with a multiplier, but convert rem to rem with a multiplier