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Cover image for CSS Lube: Highly-optimized CSS Interpreter
Yeom suyun
Yeom suyun

Posted on • Updated on

CSS Lube: Highly-optimized CSS Interpreter


The landscape of CSS paradigms has seen a constant evolution, marked by the rise of popular CSS-In-JS libraries like styled-components and emotion.
However, in recent times, there has been a notable shift in focus towards CSS libraries that emphasize "zero-runtime" approaches, such as Tailwind CSS and vanilla-extract.
These libraries are garnering attention for their promise of improved performance.
However, CSS Lube challenges the notion of relying solely on build time for achieving optimal performance.

What is CSS Lube?

CSS Lube is Highly-optimized CSS Interpreter.
It is makes improved your developer experience by implement any designs directly in markup and immediately reflect feedback.
In addition, CSS Lube parses HTML documents at runtime and render styles, so it can completely replace style files that become bloated whenever updated with a 6,558 byte(2,794 byte on gzip) js file.
Looking at the PageSpeed Insights score table below, you'll be able to guess the performance level of the CSS Lube, even considering the margin of error.
Benchmark - CSS Lube
PageSpeed Insights

What's the difference?

One of the key things about lube is that it's a zero-buildtime css Luberary.
More than half of the CSS Lube code is the part that defines shorthand, and the actual logic is less than 3kb.
With syntax and various optimizations that can be completely converted to css with just a simple string replacement, CSS Lube was able to achieve the same level of performance as zero-runtime css in js with this small bundle size.

VS. Traditional way

  • Utility-first CSS is much better in terms of maintenance and developer experience than semantic CSS.

VS. Existing CSS In JS libraries

  • This is enough. Css Lube is incredibly fast.

VS. Tailwind CSS

  • There are no additional learning curves except for a few syntax and shorthand.
  • All styles are available without write custom, and all changes are immediately reflected in the development phase.
  • You can easily switch to dark mode using basic media queries.
  • Build time is much faster because no additional steps are required to build.

VS. vanilla-extract

  • It is much more productive using various convenient shorthand without having to write a separate ts phrase.

Overall, CSS Lube aims to eliminate various constraints from the convenience of utility-first and to achieve the same level of performance as zero-runtime performance based on zero build time.


Let's take a quick look at the syntax of CSS Lube.
If you want to find out more, please see the Syntax - CSS Lube.


<div class="bg=--primary-50
  background: var(--primary-50);
  width: calc(100% - 4em);
  height: 3.5em;
  border: 2px solid red;
  border-radius: .75em;
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<div class="w=3.5
  <div class="target">red</div>
  <div class="bgc=yellow!!">yellow</div>
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Media Query

<div class="@sm&!lg@c=red">
  @media (min-width:640px) and (max-width:1023px) {}
<div class="@@container_md@fs=10px">
  @container (min-width:768px) {}
<div class="@dark&min-width=1024px@fs=10px">
  @container (prefers-color-scheme:dark) and (min-width:1024px) {}
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CSS Lube challenges existing CSS paradigms with highly optimized syntax and performance based on runtime methods.
Enjoy enhanced developer experience with no custom, no restrictions, and zero buildtime.
CSS Lube - Highly-optimized CSS Interpreter

Top comments (9)

xwero profile image
david duymelinck

I am biased because the utility-first/functional/atomic css movement feels like a step back. I think the main thought behind CSS is to abstract the content of the style attribute by using meaningful names in the class and id attributes.
What the utility-first frameworks do is treat class as the style attribute.

Now I got that out of the way. I think this is a great idea for the people that can't be bothered by organising and naming styles. Why would they want to write css files at all.

I saw in the documentation custom properties are used. So I think there still a css file? Or do you prefer a style tag?

Is the exclamation point functionality needed? What is a use case where you have no other choice than to overwrite a style?

artxe2 profile image
Yeom suyun
  1. Although svelte supports style tags, I think using separate css files for declarations such as custom properties or keyframes has an advantage in maintenance.
  2. If the parent element used the Selector feature, the child element needed an exclamation point to overwrite the style.
xwero profile image
david duymelinck

2 why is the selector feature needed? utility-first is adding styles where it's needed.

As previously stated i'm not a fan but i'm willing to learn.

Thread Thread
artxe2 profile image
Yeom suyun

Think about changing the color of the button's svg when you put the mouse on the button.
Because the area of svg is smaller than the area of the button,

.my-buton:hover svg { fill: var(--hover-color)}
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You will need to create a style like this.
And this is like :hover_svg/f=--hover-color on the class of buttons in CSS Lube.
You may also need to override the :hover style with some status value after you apply it.

<button class="bg=red :hover/bg=blue
        {is_on ? 'bg=green!!' : ''}">
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Finally, you can use the selector to change the style of components imported from an external library.

<div class="{is_on ? ':hover_div/bdc=red' : ''}">
    <Mui_Button />
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ben profile image
Ben Halpern

Well done!

overflow profile image

you got me at

stokry profile image

This is a very good idea. I am currently working on something similar that I believe will improve the developer experience and overall productivity.

artxe2 profile image
Yeom suyun

Thank you. I hope this article inspires you.

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