Mithril 1.1.6

CSS


Vanilla CSS

For various reasons, CSS has a bad reputation and often developers reach for complex tools in an attempt to make styling more manageable. In this section, we'll take a step back and cover some tips on writing plain CSS:


Tachyons

Tachyons is a CSS framework, but the concept behind it can easily be used without the library itself.

The basic idea is that every class name must declare one and only one CSS rule. For example, bw1 stands for border-width:1px;. To create a complex style, one simply combines class names representing each of the required CSS rules. For example, .black.bg-dark-blue.br2 styles an element with blue background, black text and a 4px border-radius.

Since each class is small and atomic, it's essentially impossible to run into CSS conflicts.

As it turns out, the Tachyons convention fits extremely well with Mithril and JSX:

var Hero = ".black.bg-dark-blue.br2.pa3"

m.mount(document.body, <Hero>Hello</Hero>)
// equivalent to `m(".black.bg-dark.br2.pa3", "Hello")`

CSS in JS

In plain CSS, all selectors live in the global scope and are prone to name collisions and specificity conflicts. CSS-in-JS aims to solve the issue of scoping in CSS, i.e. it groups related styles into non-global modules that are invisible to each other. CSS-in-JS is suitable for extremely large dev teams working on a single codebase, but it's not a good choice for most teams.

Nowadays there are a lot of CSS-in-JS libraries with various degrees of robustness.

The main problem with many of these libraries is that even though they require a non-trivial amount of transpiler tooling and configuration, they also require sacrificing code readability in order to work, e.g. <a class={classnames(styles.button, styles.danger)}></a> vs <a class="button danger"></a> (or m("a.button.danger") if we're using hyperscript).

Often sacrifices also need to be made at time of debugging, when mapping rendered CSS class names back to their source. Often all you get in browser developer tools is a class like button_fvp6zc2gdj35evhsl73ffzq_0 danger_fgdl0s2a5fmle5g56rbuax71_0 with useless source maps (or worse, entirely criptic class names).

Another common issue is lack of support for less basic CSS features such as @keyframes and @font-face.

If you are adamant about using a CSS-in-JS library, consider using J2C, which works without configuration and implements @keyframes and @font-face.


License: MIT. © Leo Horie.