CSS Evolution: From random() Functions to Full DOOM Rendering

What’s !important #7: random(), Folded Corners, Anchored Container Queries, and More

Technical writer Daniel Schwarz highlights the release of complex CSS functions like random() and random-item() for dynamic styling. Chrome 146 is set to enable Experimental Web Platform features like focusgroup while shifting to a bi-weekly release cycle starting September.

Why This Matters

The technical reality of CSS is moving beyond static layouts toward dynamic, browser-native logic that previously required heavy JavaScript. For instance, the transition from image-based folded corners to clip-path solutions reduces asset overhead, while the Popover API standardizes tooltip behaviors that were historically prone to accessibility and z-index failures. Implementing features like anchor positioning requires navigating non-intuitive quirks that are often mistaken for bugs but are actually deliberate architectural decisions. The rendering of DOOM entirely in CSS using 3D transforms and background images demonstrates the extreme limits of the browser’s paint and composite engines, though it remains a performance-heavy edge case rather than a production standard.

Key Insights

• Introduction of random() and random-item() functions for algorithmic styling as explained by Alvaro Montoro (2026).
• Use of font-variant-numeric: tabular-nums to eliminate layout shift in dynamic counters and financial tables (Amit Merchant).
• Implementation of anchored container queries to build dynamic toggletips in Chrome 143+.
• Niels Leenheer’s DOOM implementation uses 3D transforms and div-based surfaces to simulate a movable camera (2026).
• Chrome’s shift to a bi-weekly shipping schedule starting September to accelerate feature deployment.
• Upcoming support for the toolbar element and focusgroup in Chrome 146 under experimental flags.
• Kitty Giraudel’s clip-path solution for folded corners as an evolution from noughties-era image solutions.

Working Examples

Usage of the random() and random-item() CSS functions.

width: random(--w element-shared, 1rem, 2rem); color: random-item(--c, red, orange, yellow, darkkhaki);

Practical Applications

• Use Case: Implementing font-variant-numeric: tabular-nums in live financial tables to prevent jitter. Pitfall: Using standard proportional fonts for timers which causes horizontal layout shifts.
• Use Case: Using the Popover API for tooltips to simplify UI patterns. Pitfall: Overlooking the specific nuances and accessibility requirements of the API compared to custom implementations.
• Use Case: Utilizing clip-path for folded corner effects to replace heavy image assets. Pitfall: Using box-shadow alone which may not achieve the specific geometric clipping required for complex shapes.

References:

• https://css-tricks.com/whats-important-7/