On Cascading Style Sheets (CSS)

37 Theses on CSS and Web Development

CSS: The Pain Is Real

The Two Extremes of Writing CSS, and What We Can Learn From Them

CSS: “:has()” and the Lost Paradigm

The Lost Paradigm

The CSS Art Paradox

70% Repetition in Style Sheets: Data on How We Fail at CSS Optimization

Some Theory

Some Numbers

Some Conclusion

Appendix

Example

FAQ

Does this scale for larger sites, especially when styles are split across multiple files?

What about mixins or other techniques which prefer repetition of declarations?

Does it still make sense from a maintenance perspective to avoid repetition when declarations are only coincidentally the same?

How does e.g. moving a width declaration away from the height declaration affect maintainability and readability?

What about repetition because of vendor-specific extensions?

Why is Atomic CSS (or x) not being mentioned?

DRY CSS: How to Use Declarations Just Once, Effectively

General Steps

Special Cases

Examples

Optimizing I

Optimizing II

Editing

Tips

Tool Needs

How Declaration Repetition Developed Over Time, a Statistically Insignificant Sample

Performance of CSS Selectors Is Still Irrelevant

CSS: The Reason Why Selectors Should Be Ordered, Too

Stop Using the Old “Clearfix”

Stop Using Resets: Visual Examples of the Practical Nonsense of Resets and Normalizers

5 Reasons Against Resets, Normalizers, Reboots

The CSS Reset Contradiction

Premises

Reality

Convenience

Consequences

The Anti-Reset (to Reset to User Agent Styles)

Print Styling, the 3 Basics

1. Have a Print Style Sheet, and Be It a Negative One

2. Hide What’s Not Usable or Useful—and Be Subtle Otherwise

3. Test and Tweak

Minimal Dark Mode

Update (March 24, 2025)

CSS: When to Use Logical Properties

Should We Never Use Non-Logical Properties?

Update (August 14, 2025)

Custom Properties: Questioning “:root”

CSS Shorthand Syntax Considered Important

CSS Naked Day and the Missing Wikipedia Page

Implementation

History

Reception

Comments About This Draft

My CSS Wishlist

Thoughts on CSS in 2024

What I Appreciate

Favorites

What I Don’t Need

Why I Don’t Use CSS Preprocessors

The Craft of CSS