Moeki Kawakami

Back to Pure CSS?

The problems with Sass were clear. At the same time, the new CSS specs were very clear and worth noting. We tried to go back to pure CSS in light of this, but we ended up staying with it, so here's a summary of the process.

Why are we using Sass in the first place?

This is how it was for me personally and the team. I think everyone is different in this area.

  1. want to nest style rules when you want to style a tag without naming the class
  2. want to nest style rules by section of content to increase visibility of source code
  3. to separate files by purpose or content to improve searchability
  4. define and reuse color patterns for large projects
  5. define and reuse screen width values for media queries
  6. large projects want to use @extend to share styles
  7. some projects use @mixin to share vendor prefixes (though recently I've been using autoprefixer), define style rules, share breakpoints, etc.

What's troubling you about Sass?

1. all features are preset.

Functions that are not used are also preset. If we as a team don't clarify the criteria of which features we want to use, there is a high possibility that newly joined members will use every single feature and make the review process difficult.

2. language implementations have been deprecated and need to be migrated.

In addition to Dart Sass, Sass: Embedded Sass is Live

3. Inherently, the policy of use tends to be unstable.

Sass has a pragmatic policy that allows the specification to change to match CSS design theory that is considered useful in the real world. The following features are in the process of being deprecated and will require changes to past code


@import allows access to style conventions even when @import is used in a hierarchical manner, but this specification began to be seen as problematic, and @use was adopted as an alternative. This means that the style conventions can only be accessed in the file that invokes them.

Sass: @import

4. possible conflicts with CSS body spec.

Division using /.

In CSS, there is a property that uses / as a delimiter. In this case, Sass cannot distinguish whether the / is a delimiter or a divisor. As an alternative, we recommend Math.div.

Sass: Breaking Change: Slash as Division

🤔 By the way, what's going on with CSS?

cssdb - CSS Database defines stages** to standardization of new features, called **stages**.

|Stage|Level|Maturity Level| |:--:|:--:|:--:|Stage3 |Stage4|Standardized|High |Stage3|Embraced|: |Stage2|Allowable|: |Stage1|Experimental|: |Stage0|Aspirational|Low

It seems that as the Stage goes up, the browser support actually improves. Also, [postcss-plugins/plugin-packs/postcss-preset-env]( preset-env) allows you to comply with this stage and use features that will be standardized in the future.

It seems that there are quite a few features that we used to use in Sass.

SassCSSPostCSS Plugin
nestingnesting rule (stage 1)postcss-nesting
color reusecustom property (stage 3)postcss-custom-property
reuse media querycustom media query (stage 2)postcss-custom-media
class inheritanceunder discussionpostcss-extend
Mixinunder discussion 1postcss-mixins, postcss-apply

Please do some research on the notation of each rule.

How to reproduce Mixin for different purposes

  • Define common style rules => Do not adopt single class
  • Common vendor prefix => Autoprefixer
  • Common breakpoints => custom media query in CSS

Low-stage rule specs are very unstable

The stage defined by W3C is not an official release version and its use is less stable. Low stage must also be taken into account that the specification is more likely to change or be REJECTED. Before one has little knowledge or experience with draft CSS, it is better to follow the default (stage 2) of postcss-preset-env.

For example, the nesting rule is still in stage 1, so the specification is likely to change. If you implement it in postcss-preset-env, you may have to re-implement just the nesting part later.

Maybe it's too early to adopt postcss-preset-env.

It may still be too early to adopt postcss-preset-env after all the above discussion. From now on.

  • We will use CanIUse and other tools to see how browsers support it.
  • If the stage of the function we want to use reaches 4 and browser support is sufficient, we will adopt it.
  • We will continue to adopt PostCSS for approaches other than CSS itself, such as autprexier.

I think that is what I was thinking. Thank you very much.


  1. @apply is being discussed, but apparently there are technical issues that are making it difficult.

← Back to list