What's configured here (see config/page_level/showcase-links.config.php):

• links.style = 'underline-slide' — the underline grows in from the left on hover/focus and retracts on mouse-out.
• links.color = 'var(--color-accent)' — the underline (not the link text) uses the accent colour instead of following the text colour.
• links.thickness = '2px' — a heavier underline bar than the default.

Try hovering this underline-slide link to see the site-wide page style in action.

This one is overridden per-instance back to the default behaviour: underline-hover link — set directly with a data-link-style attribute on the anchor, which takes priority over the page-wide setting.

Still to review: whether the accent-coloured underline reads clearly enough against the default text colour, and whether a third variant (e.g. a colour-fade underline) is worth adding.