c2n/web-componentsv0.0.6
GitHub repository

Accordion

Connected, animated panels with shared borders and single or multiple expansion.

c2-accordion combines c2-details panels into one disclosure surface: a shared frame, single-line dividers and rounded outside corners. Panels animate open and closed together, and their chevrons rotate with the same timing. Opening a panel closes its siblings by default; add multiple to keep several open. All panels can be closed in either mode. Each panel provides its own label, content, disabled state and header slots through c2-details.

Installation

npm install @c2n/accordion

Importing @c2n/accordion also registers c2-details.

Usage

Only direct c2-details children participate in grouping: place them inside the accordion without wrapper elements. Nested accordions operate independently, and panel name values are unnecessary. If several panels initially have expanded, the first in DOM order stays open in single mode. Removing multiple applies the same rule.

Set a panel’s expanded property or call its toggle(force?) method to control it programmatically. Listen for the non-bubbling toggle event directly on each panel. A disabled panel blocks user interaction and toggle(), but the accordion can still close it when a sibling opens.

The accordion owns the frame through --c2-accordion--border-width, --c2-accordion--border-color and --c2-accordion--border-radius. Its default --c2-accordion--gap: 0px joins panels without doubled borders or rounded inner corners. Set a positive gap to separate them into individually rounded cards.

The accordion applies the same border to every side of each panel. To drop a side, for example a flush list without left and right borders, target the panels from the page; a document rule beats the accordion’s slotted defaults:

c2-accordion.flush {
  --c2-accordion--border-radius: 0px;
}
c2-accordion.flush c2-details {
  --c2-details--border-left: none;
  --c2-details--border-right: none;
}

Set --c2-accordion--transition-duration (default 300ms) to adjust panel expansion and chevron rotation together, or 0ms to disable them. Reduced-motion preferences disable transitions automatically. Panel height is animated by the component itself (a slide plus a fade of the content), so opening and closing look the same in every browser.

Use inherited --c2-details-* properties for header colors, content padding and typography. Set frame and animation properties on the accordion itself; see the Gallery for styled examples.

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