0.16.0 • Public • Published


Smoother is a Sass library designed for a smoother front-end development experience. Smoother is filled with easy-to-use functions and mixins that aid in UI creation, serving up workflow enhancing utilities and generating production ready animations and element styles.

In addition to the many utility functions that extend and improve on the functionality of the built-in Sass modules, and the mixins that allow for intuitive and fast style development without repetition, this library focuses heavily on aiding in the creation of CSS animations.

Smoother allows you to create a wide range of smooth and customizable visual effects, without having to deal with messy clip-path coordinates, complicated animation keyframe creation, or other verbose and complex code blocks.

Table of Contents

  1. Version
  2. Content
  3. Sass Version Requirement
  4. Deployment
  5. Documentation
  6. Parameter Aliases
  7. Recently Improved
    1. Version 0.16.0 Patch Notes
    2. Version 0.15.0 Patch Notes
    3. Version 0.14.0 - 0.14.1 Patch Notes
    4. Version 0.13.0 - 0.13.1 Patch Notes
    5. Version 0.12.0 - 0.12.2 Patch Notes
    6. Version 0.11.0 Patch Notes
    7. Version 0.10.0 - 0.10.1 Patch Notes
    8. Full Patch History
  8. Betterize
  9. More Info
  10. Questions
  11. Contributions
  12. License
  13. Authors
  14. Thanks


Smoother is currently in active development. Almost every day there are updates to the functionality or documentation of this library. If you download Smoother for use in a project, I recommend updating it frequently to get optimal functionality from it.

This is smoother version 0.16.0 - Last updated: 03/31/24


Because _smth.scss is a Sass library comprised of functions, mixins and variables, importing it into your project won't add any overhead or increased file size to your project's stylesheet except for the parts that you actually use by calling a function, variable, or by using a mixin with @include. The current unpacked size of the package itself is 1.11MB.

Smoother currently contains:

  • 180+ Mixins, including...
    • Over 40 easily configurable animation types, allowing for more than 250 unique animations
    • 115+ utility mixins for things like creating responsive ratios, box-shadow effects that adhere to Material Design, clamping text to a given number of lines, creating corner ribbons, centering elements, browser-targeted styling, media queries, making "hamburger" menu buttons and much more!
    • More than 20 element shapes created with a combination of clip-path, pseudo-elements, and border-radius
  • 100+ Functions, _including functions that...
    • Extend Sass' existing module's method functionality (ex: list-update() function)
    • Manipulate colors and convert between syntax types
    • Enhanced data type checking
    • Data type conversion/casting
    • Calculate unit conversions (such as px to rem)
    • Fix floats to a given number of decimal places
    • Return custom cubic-bezier curves for timing functions based on Penner equations.
    • Return custom calc() equations based on trigonometric functions for use in animations and transitions
    • Calculate the "least square fit" or trend-line of a mapped set of points (very useful for setting responsive font sizes)
    • Functions that aid in the creation of mixins and placeholders
    • Much more!
  • A modern, opinionated CSS normalization file written in Sass called _betterize.scss
  • A print style file written in Sass called _smooth-print.scss
  • A collection of helpful and configurable !default variables
  • Useful documentation generated from the SassDoc annotations, written for every function, mixin, and variable.

Sass Version Requirement

Not every mixin and function in Smoother will compile unless you are using DartSass version 1.57.0 or higher.

Smoother uses many of the more recent Sass features that are not available in the now deprecated Ruby and C/C++ versions of Sass (RubySass and LibSass).

It is strongly recommended that you use the most recent version of DartSass available. At time of writing, that is version 1.72.0. Smoother will work with DartSass >= 1.57.0 (the version string.split() was added), but it is preferable that you use a version >= 1.69.1, as features are coming soon that will take advantage of the new ability to have first-class mixins.

There are some breaking changes coming in the new versions of Sass, so if you need to get an older project ready with the new syntax, check out the Sass Migrator tool.


To download Smoother for your project using NPM, use the following from the command line in your project's root directory.

npm i -D smoother
npm i smoother

Then you can copy the files from the node_modules folder to your project's sass directory with the following CLI directive (changing the path to your own project's desired directory):

cp -r node_modules/smoother/src/{betterize,smthr} www/sass/vendors/

The link to _Smoother on the NPM website here:

You can also download the repo manually from Github and copy/paste the contents of the ./src folder (the folders /smthr and /betterize), into your own project. If you are taking that route, download a zipped copy of the code by going to the top of this README page and looking for the green colored "<> Code" button. Click that and choose "Download ZIP". Once it is downloaded, unzip the project folder.

Another way is to clone the repo using one of the below methods:

HTTPS method:

git clone

GitHub CLI method:

gh repo clone stephenmirving/smthr

Whether you downloaded from NPM, cloned the repo, or just grabbed it manually, find the package folder (If you downloaded from NPM that would be /node_modules/smoother) and go into the src folder. Copy the smthr and betterize (betterize is optional) folders into your own project's styling directory, in the folder where you keep the rest of your .scss files. This is probably in a /sass or /scss folder, or within one of the subdirectories of that folder.

You can do this from the command line like this:

cp -r node_modules/smoother/src/{betterize,smthr} your/path/sass/vendors

If you are breaking your Sass code down into partials with the 7-1 pattern or something similar for organizing your .scss files, you would likely put the smthr folder inside of the vendors subdirectory.

From there you currently have two choices with Sass for how to load the library into your project.

If you are still using the old, and soon to be deprecated, @import directives in your project's main .scss file, then you can simply @import the library at the top of the other partials you @import.

// FILE: sass/main.scss
@import 'vendors/smthr/smth';
@import 'vendors/betterize/betterize';

@import 'base/typography';

@import 'layout/grid';
@import 'layout/navigation';
@import 'layout/header';
@import 'layout/footer';

@import 'components/buttons';
// ... The rest of your @import directives for all your partials...

Inside of your partials, you would be free to call any of the functions, mixins, or variables that are available in the Smoother library, because @import loads everything globally.

The downsides of this method are twofold:

  • None of these members will be namespaced and could increase the potential for naming collisions between the Smoother library, your own project's members, and any other third-party libraries or frameworks you use.
  • This method will soon be deprecated by Sass, which lists many reasons for discouraging and deprecating the feature in their documentation.

The better choice would be to follow the specification for the newer versions of Sass (At time of writing, DartSass version 1.72.0). Doing it this way will ensure your project will continue to compile if you update your Sass version past the point that @import is deprecated (most likely sometime this year in 2024).

To follow the new specification what you need to do is to put _index.scss files inside each of your sass folder's main subdirectories, and these files should have @forward directives for every other partial in the folder. So you may have a layout folder containing your layout partials, create a file in that folder called _index.scss and that file should look like this:

// FILE: sass/layout/_index.scss

@forward 'grid';
@forward 'navigation';
@forward 'header';
@forward 'footer';
// all other partials in the sass/layout/ folder should have a @forward directive here

Then in your main.scss file where formerly you woud use @import to load all your partials, now you would instead write something like this:

// If you want to use betterize, load it first
@use 'vendors/betterize/betterize';

// Then load all your project's partials by loading in the folders.
// Sass will automatically look for the _index.scss file in each folder
// and then forward all the files that the _index.scss has an @forward for.
@use 'utilities';
@use 'base';
@use 'layout';
@use 'components';
@use 'pages';
@use 'themes';

// If you want to use the print styles, load them at the end
@use 'vendors/betterize/smooth-print';

Then, inside each of your partial files, if you want to use a variable, function, or mixin from the Smoother library, you would need to write an @use directive for it at the top of that partial file.

You can do this while namespacing the library to smth and then you can call the functions, mixins, and variables in the library using that as a prefix, like this:

// FILE: sass/pages/_home.scss

@use '../vendors/smthr/smth' as smth;

.element {
  @include smth.bounciness('down', 0.6s);

  font-family: smth.font-stack('primary', smth.$font-stacks);
  color: smth.invert-color($color-brand)

Alternately, you can choose to not explicitly declare the namespace, and since Sass will then namespace it to the last part of the file path, which is smth.

// FILE: sass/pages/_home.scss

@use '../vendors/smthr/smth';

.element {
  @include smth.bounciness('down', 0.6s);

If you prefer to namespace the module to something shorter, you can choose almost anything you want that is not used by another module. While there is no explicit warning against it in the documentation, I recommend not choosing a $, #, @, e, _ or - character as your namespace, as this could potentially cause conflicts due to $ being used for variables, # being used for interpolation, @ being used for at-rules, e being reserved for the mathematical constant e, and _ or - being used at the start of member names to make those members private. At the very least, it could screw up your syntax highlighting, so choose something unique.

@use '../vendors/smthr/smth' as ~;

.element {
  color: ~.invert-color($color-brand);

If you aren't worried about potential namespace collisions between Smoother, other third-party libraries, and your own code, then you can import it without a namespace by using as * after the file URL, and not have to worry about using a namespace prefix when calling the functions, mixins, or variables in the library. That might look like this:

// FILE: components/_buttons.scss

@use '../vendors/smthr/smth' as *;

.button {
  color: invert-color($color-brand)

You can see a small-scale example of this newer structure for loading Sass modules by looking through the test folder in this repository.

For more information about migrating away from the soon-to-be-deprecated @import and using the newer @forward and @use directives, see the offical Sass documentation for:


Smoother documentation:

In the future, there will be a Getting Started section and a comprehensive wiki with example code snippets that show their CSS output, with pictures and video examples of the code's effect on the page. For now though, you can get started with the documentation page, generated for the library using the SassDoc annotations in the code.

Parameter Aliases

Most of the documentation and SassDoc annotations will describe the valid parameters that you can pass to the various functions and mixins, and the forms those parameters can take. In an attempt to make the library more easy to pick up and use, many alias values were created for most of the commonly used keyword strings that you could pass as parameters to the library members. So, if an animation mixin's $direction parameter accepts a value of top right, to indicate that it should animate in from the top right, you should expect that the mixin would also accept alias values of 'top right' (in a quoted string or without quotes), top-right, topright, right top, right-top, or just tr or t-r, along with several more potential valid values that will resolve as top right.

To get an idea of the full list of aliases for these keyword values, see the $map-alias-resolutions variable by checking the documentation, or by looking for it in the src/smthr/variables/_maps.scss file.

Recently Improved

Version 1.0.0 is coming soon with more animations, more shapes, and more utilities. There will be an easier method for installing and updating new versions without having to copy folders every time, a Getting Started guide, and a website with a demo for every mixin and function to help you start using Smoother.

Version 0.16.0 Patch Notes

  • Added the some() function that tests whether some items (at least one) from a List pass the test implemented by a given function.
  • Added the list-sort() function that sorts a List based on alphabetical order or a custom provided order.
  • Added the str-compare() function that helps list-sort() compare two string based on the order provided.

Version 0.15.0 Patch Notes

  • Added first-of() function that returns the first item in a List or Map.
  • Added last-of() function that returns the last item in a List or Map.
  • Added is-empty() function that returns true if a List or Map has a length of 0.
  • Added last-index() function that returns the last index of $value in a List, as opposed to the built in method list.index() which returns the first index of $value in a List.
  • Added the list-loop() function which will shift the elements in a List forwards on a loop by a given number of positions.
  • Added the list-prepend() function will a value to the first index of a List, shifting all the other elements on the list down by 1 index.
  • Added the list-remove-nth() function that will remove a value from a List at the given index.
  • Added the list-replace-nth() function that will replace a value from a List at the given index.
  • Added the list-remove-duplicate() function that will remove all duplicates from a List.
  • Added the list-reverse() function that will reverse the order of a List.
  • Added the list-slice() function that will slice a list between a start and end point.
  • Added the list-range() function that creates a List of numbered values from 1 to a provided value.
  • Added the list-to-map() function that casts a List into a Map.
  • Added the every() function that tests whether all items from a List pass the test implemented by a given function.
  • Renamed the src/smthr/functions/_purge-list.scss partial to _list-purge().scss to match the naming convention of the new list functions. purge-list() will live on as an alias of list-purge().
  • Renamed the src/smthr/functions/_update-list.scss partial to _list-update().scss to match the naming convention of the new list functions. update-list() will live on as an alias of list-update().
  • Improved documentation.

Version 0.14.0 - 0.14.1 Patch Notes

  • Added font-face() utility mixin.
  • Modified the scrollbar() mixin so that you can pass a $size of 0 and hide the scrollbar entirely.
  • Added the map-is-deep() and map-is-flat() functions that return a Boolean indicating if a given map has any nested maps, and is either deep or flat/shallow.
  • Added map-get-key-chain() function that returns the "chains" of nested keys.
  • Renamed the _in-list.scss partial to _list-contains.scss. The in-list() mixin is still an alias value for list-contains() but any @use directives pointing to _in-list.scss will have to change to _list-contains.scss
  • Added list-chunk() function that chunks a list into multiple lists of a given length.
  • Added hoctive() mixin that applies the provided content to the :hover, :focus, and :active pseudo-classes in one selector group.
  • Added hocus-visible() mixin that applies the provided content to the :hover, and :focus-visible pseudo-classes in one selector group.
  • Added the smart-underline() mixin that applies an underline that gets bigger on hover and is removed on selection/highlighting. This is an effect similar to the default link effect in Safari.
  • Improved the to-list() function by having it first detect if the $value is a Map and then calling the map-to-list() function for those values.
  • Improved the map-to-list() function adding a $separator parameter so you can choose how the new list is separated just like the to-list() function.
  • Added all the new functions to the @use directives in functions-walk() and walk() functions.

Version 0.13.0 - 0.13.1 Patch Notes

  • Made the caret() mixin more robust by adding size and color customization to the available parameters and enabling pointing the caret in diagonal directions. You can also now place the caret in a new positioning context and choose whether the caret will be in a ::before or ::after pseudo-element with the optional $placement parameter.
  • Added new utility mixins: debug(), which gives visual indicators for debugging layouts and bg-cover(), which is a shortcut for setting a background image to cover.
  • Added gradient-stripes() mixin (with alias of stripes()), which generates a stripe gradient with a direction and a list of colors.
  • Added more than 15 new semantic relational mixins to the collection in _family.scss. These new mixins take advantage of the new selector list arguments feature for nth-child and :nth-last-child, as well as the relational pseudo-class selector :has.
  • Added $intensity parameter for the depth-level() mixin that works as a modifier for the shadow effect's opacity.
  • Updated Betterize to version 2.07
  • For broader browser support, changed all instances of overflow-wrap in mixins to the alias property word-wrap
  • Improved some of the documentation

Version 0.12.0 - 0.12.2 Patch Notes

  • Renamed the zoom-in() animation mixin to bg-zoom(). It still has the same alias of ken-burns(), along with the new alias of bg-zoom-in() and img-zoom().
  • Created new animation mixin called zoom().
  • Renamed the wobbliness() animation mixin to just wobble(). wobbliness() has been left as an alias for wobble()
  • Added new animation mixins: speed(), and wiggle().
  • Added prefix() utility mixin that takes a map of property:value declarations and adds a list of vendor prefixes to the properties. Though most people are now using Autoprefixer, this may still be useful to some.
  • Fixed error in
  • Removed unnecessary dependencies

Version 0.11.0 Patch Notes

  • Greatly improved the robustness of the gradient() mixin.
    • The mixin now allows you to apply a gradient effect to text, not just backgrounds.
    • You can now pass true to the new $is-repeating parameter to make the mixin use the repeating-linear-gradient() and repeating-radial-gradient() CSS functions rather than the non-repeating linear-gradient() and radial-gradient functions.
    • Making a radial gradient with this mixin now allows you far more control for different types of radial gradients with different parameters. Previously the only type of radial-gradient the mixin could produce was the ellipse at center parameter. Now you can enter virtually any valid starting value for a radial-gradient() with the $orientation parameter.
    • You can now pass two value percentage position parameters for $start-position and $end-position, instead of just one value syntax available previously.
    • You can also now pass true to the new $supports-legacy parameter and have all the vendor prefixes and the old IE filter gradient syntax applied at same time as fallbacks for the modern gradient syntax.

Version 0.10.0 - 0.10.1 Patch Notes

  • Renamed the poof() animation mixin to vanish()
  • Added new animation mixin that is now named poof()
  • Added new animation mixin poof-puff() that is a combination of the puff() animation and the new poof() animation which creates a more exaggerated effect.
  • Updated Betterize to version 2.0.5
  • Greatly reduced the size of the Smoother NPM package by removing several large image assets from the test directory when publishing the package. They were causing the package to take up around 27MB instead of being slightly less than 1MB, which is what the package takes up now.

Full Patch History

To view the view the full record of all the patch notes for Smoother, go to


If you want to use the modern normalization replacement file _betterize.scss, or the print style file _smooth-print.scss, simply follow the same instructions above by copying the betterize folder into the vendors folder in your project, or in any folder that works for the way you have organized your project. Just make sure that the betterize folder exists in the same directory in your project as the smthr folder. Code snippets showing how to import it are above, included within the same snippets showing how to load Smoother.

This version of Betterize was refactored to be configured for use along with the Smoother library. If you choose to use _betterize.scss, you can most likely remove any other CSS normalization or reset files such as normalize.css or reset.css. You may also be able to avoid many styles you would have put inside a _base.scss partial.

You can check out the Betterize repo for more information, or to download versions of Betterize written in .css, .sass, .less, and .scss formats, all of which are free from any Smoother dependencies when downloaded from its own repository.

You can also install the Smoother dependency-free version of Betterize with NPM:

npm i -D betterize
npm i smoother

Then you can copy the files from the node_modules folder to your project's sass directory with:

cp -r node_modules/smoother/src/{betterize,smthr} www/sass/vendors/

More Info

For more information about how to structure your project with 3rd party libraries, please refer to the official Sass Documentation.

For more information about how to update your project's Sass files to use the module system and replace the soon-to-be-deprecated @import feature with the newer @use and @forward features, refer to the documentation for the sass-migrator tool.


If you have any questions about how to use Smoother that cannot be answered by the Smoother documentation, or if you have any issues, suggestions or comments, I would be happy to help anyone who reaches out. You can find me on X/Twitter at @metric_dev.

Feel free to ask me anything you like in a tweet, or shoot me a DM (though if you are not verified on X/Twitter I may not see the DM).


If you would like to contribute to Smoother, whether it is to add something new or fix a bug you have found, check out the Contributions document.


Smoother is distributed under an MIT License.

TL;DR: Anyone can use this code however they want but it would sure be nice if they also included a copy of the above license.


Created by Stephen M Irving

This library contains work inspired by others, as well as some forked code. This includes code by:


Thank you to the contributors and maintainers of Sass.

Thank you to the creators and writers at, Smashing Magazine and the Mozilla Developer's Network, who are often my first source for keeping up with the changes in CSS and Sass.

Thank you to my father, Michael Graham Irving.

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