August 2026 saw three web platform features cross Baseline thresholds, alongside a community post on keeping AI coding agents aligned with current platform standards.

Community: design token skills and Modern Web Guidance

Brecht De Ruyte looked at how Google's Modern Web Guidance skill set steers AI coding agents toward current, Baseline-aware CSS and HTML rather than outdated patterns. The post covers combining Modern Web Guidance with custom design token skills, which preserves design system consistency while keeping output within modern platform standards. Details are in Modern Web Guidance as a starting point for my own token skills: getting agents to write better CSS.

Newly available in August 2026

Two CSS features gained support across all core browser engines during the month, reaching Baseline Newly available status.

:paused

The :paused pseudo-class matches playable media elements— and among them—while playback is paused. It also matches elements that have loaded but have not started playing yet. Because it distinguishes paused playback from transitional states such as buffering or seeking, media player controls and surrounding UI can express playback state in CSS alone. See the MDN documentation.

sibling-count()

sibling-count() returns an integer for the total number of siblings sharing a parent, counting the element itself. Where counter() yields a string formatted for generated content, sibling-count() resolves to an integer usable directly in math with calc(). Children can therefore derive proportional layout dimensions, column widths for example, from their sibling count—no JavaScript or fixed styles required. See the MDN documentation.

Widely available: Declarative Shadow DOM

Declarative Shadow DOM reached Baseline Widely available, meaning 30 months of support across all core browser engines and safe use without polyfills. It defines shadow roots in HTML itself, via the