mapbox / mapbox/assembly

Do we need to resolve custom properties?

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#972 1 comment 0 reactions 0 assignees View on GitHub

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2 estimate-2 icebox jira-sync-complete p2
Dominant language
CSS
Stars
138
Forks
26
Avg merge
1d 7h
Merged PRs (30d)
3

Description

With https://github.com/mapbox/assembly/pull/970 - our browser support targets all support [css custom properties](https://developer.mozilla.org/en-US/docs/Web/CSS/--*). Should we revise our build system to convert the `variables` option to a set of `:root` CSS properties? Would save us from needing to resolve every variable in our CSS at build time.

Are there costs to doing this? Likely compressed file size would not be impacted but could time to first paint take a hit? Here's an article on CSS variable performance, but it exclusively discusses the performance of _changing_ variables at runtime: https://lisilinhart.info/posts/css-variables-performance/ and after some quick looking, couldn't find any existing documentation of the performance cost of using variables.

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Research direction

No file or test is named. Start by reviewing how the build system handles the `variables` option and the browser support targets referenced in pull request #970; compare resolving variables at build time with emitting `:root` custom properties, including first-paint and compressed-size effects. Done means reaching a documented decision on whether to change the build behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
css
Domain
build-system, frontend
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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