[zelphirkalt]

I am more talking about "Only ever include the CSS rules we need." instead of "Lets take the whole of bootstrap! Oh damn, we have to somehow reduce it!".

If memory serves me right, you could compile the Bootstrap library and choose the parts you needed. Not sure if that is still true for Bootstrap 5. If it is not possible, it stands to reason, that perhaps one should not use Bootstrap 5 and instead write good styling oneself, without all the stuff, that will never be used on the site anyway.

CSS can be tricky, but in the end, reasonable styling is usually not that hard to do. Even responsiveness can be done mostly without media queries these day, unless you want content to change, if layout changes. It used to be much harder, when our browser standards were not that far. Nowadays we have flex and grid and more standardized interpretations of CSS rules in browsers. We can make navigations, menus, tiles and whatever all responsive without that much work put in.

[saint-loup]

From the Parcel CSS page : it does 'tree shaking', which automatically eliminates unused code. Not details on what that implies, though. Tools like PurgeCSS (used by Tailwind pre-v3) comb through the HTML for matching selectors, but I'm not sure if Parcel does the same thing.

Anyway, as others comments said, these kind of tools nowadays are more 'transformers' than mere 'minifiers'.

[zelphirkalt]

That's really nice, but to me still sounds like the wrong way to go. Instead of reducing something that is too much, that which is too much should not have been added in the first place. We are doing work here, removing, what we have previously added.

I wonder how much ineffective styling still remains after "tree shaking". I guess the fancy tree shaking is out of luck, if we add unnecessary styling to elements, which are indeed used. It seems a really hard problem to solve automatically, to transform CSS in a way, that takes care of redundancies and unnecessary styling, while still maintaining the readability, which well crafted CSS can have.

[dmitriid]

> that which is too much should not have been added in the first place.

The problem is, with CSS you don't know if you've added too much. As the project evolves, and code and styles change there's literally no way of knowing if a certain CSS rule is still in use Well, except regexp'ing the whole project looking for matches.

[selcuka]

> regexp'ing the whole project looking for matches

That's basically what these tree-shaking tools do.