postcss-pixels-to-rem

postcss-pixels-to-rem is a PostCSS plugin that converts items sized in pixels in CSS code to either rems or ems.

It will convert several types of CSS notation. It is designed to be versatile by doing basic px to rem conversion and also to work with legacy code that was written against the deprecated Pixels to Rems and Pixels to Ems Sass functions from Bourbon. It converts the notations rem(<value>) to rems and em(<value>) to ems. It also converts <value>px code to rems or ems.

In postcss-pixels-to-rem default mode, an input of:

h1 {
    font-size: rem(32);
}
h2 {
    font-size: em(24):
}
p {
    font-size: 16px;
}

will result in an output of:

h1 {
    font-size: 2rem;
}
h2 {
    font-size: 1.5em:
}
p {
    font-size: 1em;
}

Installation and use

postcss-pixels-to-rem requires PostCSS to be installed. To install postcss-pixels-to-rem:

$ npm install --save-dev postcss-pixels-to-rem

In gulpfile.js

var postcss = require('gulp-postcss')
var pixelstorem = require('postcss-pixels-to-rem');

Gulp task:

gulp.task('css', function() {
    var plugins = [
        pixelstorem()
    ];      
gulp.src('source/sass/styles.scss')
.pipe(postcss(plugins))
.pipe(gulp.dest(public/css));
});

Defaults

• Default base for conversion is 1rem = 16px.
• Default output for rem(<value>)is rem.
• DEfault output for em(<value>) is em.
• Default output unit for <value>px is rem.
• Default is to convert values in media queries.

Options

postcss-pixels-to-rem accepts optional settings that override default settings.

gulp.task('css', function() {
    var plugins = [
      pixelstorem({
        base: <value>,
        unit: "rem" or "em",
        exclude: ["declaration"]
      })
    ];
    gulp.src('source/sass/styles.scss')
    .pipe(postcss(plugins))
    .pipe(gulp.dest(public/css));
});

Optional values:

• base: <value> - Accepts a unitless value. Resets the base font size for conversion to rems or ems.
• unit: "rem" or "em" - Accepts unit value of either "rem" or "em" as a string. All items will be output in the unit value set here, including values set by rem(<value>) or em(<value>) notation.
• exclude: ["declaration"] - any declaration type to exclude from conversion, eg, border, border-radius, etc. These declarations will be excluded globally.
• mediaQueries: boolean Setting this to false prevents conversion of values in media queries. Default value is true.