Uplink CSS Columns

Uplink CSS Columns adds an accessible inspector panel, an editor preview, and
server-rendered front-end styles for CSS Multi-column layouts. It has been tested
with WordPress 7.1.

Group, Paragraph, and List blocks receive the complete set of controls. Any
other registered block nested inside a Group receives the Span parent columns
control without receiving unrelated container settings. Individual List Item
blocks receive fragmentation controls for managing breaks between list items.

Features

• Column count, width, gap, and fill.
• Column rule shorthand, width, style, color, and draft visibility controls.
• Optional padding and margin for the selected multi-column block.
• Draft column height and wrapping controls with editor warnings.
• Column spanning for any registered block inside a Group.
• Break before, break after, and break inside fragmentation controls.
• CSS custom properties and functions such as var(), calc(), min(), max(), and clamp().
• Sanitized server-side output that avoids modifying core block save markup.
• Clear blank/default behavior and examples in control descriptions.

The plugin stores its settings as namespaced block attributes. Front-end
declarations are sanitized and injected during block rendering, which avoids
the block-validation errors caused by changing core block save markup.

The established Level 1 CSS properties have broad browser support. Column
height, column wrap, and column rule visibility are draft features and are
clearly marked as experimental. Unsupported properties are ignored by browsers.