Fork notice

This is a fork of elm-css. Elm-css is abandoning support for generating CSS files and moving to locally scoped CSS rules. The original author believes the new locally scoped design is the One True Way and will be devoting his energy to the new design. This fork is ensure that the 11.x branch (the last version before the design change) of css-in-elm will be ported to future versions of Elm. This fork is commited to maintaining the old stylesheet generating design forward into future versions of Elm.

If you like using Elm to write CSS rules, i.e. you like the power and flexibility of a fully featured functional programming language compared to Sass, Less, or other css preprocessors, then this is the project for you.

css-in-elm

Quick Start

Try it out! (make sure you already have elm and elmi-to-json installed, e.g. with npm install -g elm elmi-to-json)

$ npm install -g css-in-elm
$ git clone https://github.com/ThinkAlexandria/css-in-elm.git
$ cd css-in-elm/examples
$ css-in-elm
$ less homepage.css

A gentle introduction to some of the features of css-in-elm is also available in the tutorial.

About

css-in-elm lets you define CSS in Elm.

Here's an example of how to define some css-in-elm styles:

module MyCss exposing (..)

import Css exposing (..)
import Css.Elements exposing (body, li)
import Css.Namespace exposing (namespace)


type CssClasses
    = NavBar


type CssIds
    = Page


css =
    (stylesheet << namespace "dreamwriter")
    [ body
        [ overflowX auto
        , minWidth (px 1280)
        ]
    , id Page
        [ backgroundColor (rgb 200 128 64)
        , color (hex "CCFFFF")
        , width (pct 100)
        , height (pct 100)
        , boxSizing borderBox
        , padding (px 8)
        , margin zero
        ]
    , class NavBar
        [ margin zero
        , padding zero
        , children
            [ li
                [ (display inlineBlock) |> important
                , color primaryAccentColor
                ]
            ]
        ]
    ]


primaryAccentColor =
    hex "ccffaa"

Here's what you can do with this code:

• You can generate a .css file from it.
• You can use it to generate type-checked inline styles.
• You can share NavBar and Page with your Elm view code, so your classes and IDs can never get out of sync due to a typo or refactor.
• You can move this code into your view file and have your styles live side-by-side with your view functions themselves.

css-in-elm works hard to prevent invalid styles from being generated; for example, if you write color "blah" or margin (rgb 1 2 3), you'll get a type mismatch. If you write (rgb 3000 0 -3) you'll get a build-time validation error (RGB values must be between 0 and 255) if you try to compile it to a stylesheet.

css-in-elm draws inspiration from the excellent Sass, Stylus, and CSS Modules. It includes popular features like:

• Mixins
• namespaces
• nested media queries (and nested selectors in general, like how Sass does them)

There are two popular approaches to using it; you can use either or combine both of these, depending on your needs and preferences.

Approach 1: Inline Styles

One way to use css-in-elm is for inline styles, using the asPairs function:

styles =
    Css.asPairs >> Html.Attributes.style

button [ styles [ position absolute, left (px 5) ] ]
    [ text "Whee!" ]

This approach is the simplest way to get started with css-in-elm. One advantage of inline styles is that these can be dynamically changed at runtime; a limitation is that CSS pseudo-classes and pseudo-elements cannot be used with inline styles.

Approach 2: Generating CSS files

You can also use css-in-elm as a CSS preprocessor which generates separate .css files.

To do this, you will need to create a special directory at the top level of your process to contain an elm application used only to generated CSS files.

mkdir css
cd css/
elm init

Then you will need to install both the node module and the Elm library:

npm install -g css-in-elm
elm package install ThinkAlexandria/css-in-elm

Finally you'll need a special file with a port for css-in-elm to access inside the css/src directory:

module Stylesheets exposing (..)

import MyCss
import HomepageCss

fileStructure =
        [ ( "index.css", [ MyCss.css ] )
        , ( "homepage.css", [ Homepage.css, MyCss.css ] )
        ]

Run css-in-elm from the root of your project (containing the css directory). Then include that css file in your web page.

The above css-in-elm stylesheet compiles to the following .css file:

body {
    overflow-x: auto;
    min-width: 1280px;
}

#dreamwriterPage {
    background-color: rgb(200, 128, 64);
    color: #CCFFFF;
    width: 100%;
    height: 100%;
    box-sizing: border-box;
    padding: 8px;
    margin: 0;
}

.dreamwriterNavBar {
    margin: 0;
    padding: 0;
}

.dreamwriterNavBar > li {
    display: inline-block !important;
    color: #ccffaa;
}

Examples

There are a few examples to check out!

• json-to-elm which can see be seen live here
• the examples folder, which contains a working project with a README
• the example above

Using css-in-elm with Elm view code

Here's how to use css-in-elm in your projects:

In your Elm code, use the same union types to represent classes and ids. Then they can't get out of sync with your CSS. To do this, you'll need special versions the of id, class, and classList functions from elm-html.

Missing CSS properties

css-in-elm is still in development. Not all CSS properties have been added yet. If you run into this problem, css-in-elm includes the property function. It takes two Strings; the property key, and its value.

e.g.

We want z-index, but suppose css-in-elm did not implement it. We would define it ourselves:

import Css exposing (..)

zIndex : Int -> Mixin
zIndex i =
    property "z-index" <| toString i

Now zIndex 9999 is available to use inside our Stylesheet.

Related Projects

• Elm CSS Normalize