Alpha This design book is in early development. Components and tokens will change. See the changelog.

JACB Services — Design System

Design once.
Build consistently.

A shared design language for GTV, the JACB Services helpdesk app, and any future projects — built on GOV.UK Design System principles with our own tokens, themes, and components.

v1.5 — Tarbert · 21 March 2026 · IBM Plex Sans / Mono · Two themes

Latest · v1.3

Header hover fixed, JACB branding, open source statement — v1.6 Tarbert

Nav hover colour corrected, logo updated to JACB, footer updated to JACB Services, open source position added. Full changelog →

Foundations

The core tokens that all components are built on — colour, typography, and spacing.

Foundation

Colour

Brand purples, status colours, and the dark theme token overrides.

2 palettes · light + dark

Foundation

Typography

IBM Plex Sans and IBM Plex Mono. Eight scale steps from 12px to 40px.

2 typefaces · 8 steps

Foundation

Spacing

4px base unit. Named scale from space-1 (4px) to space-16 (64px).

8 steps · 4px base

Components

Ready-to-use HTML and CSS components. Each includes a rendered example and copy-paste code.

Component

Button

Primary, secondary, warning, and ghost variants.

4 variants

Component

Notification banner

Success, error, warning, and info banners with left-border treatment.

4 variants

Component

Card

Standard and branded cards, plus a responsive card grid layout.

2 variants · grid

Component

Table

Standard and striped tables with numeric column alignment.

2 variants

Component

Navigation

Site header with horizontal nav and vertical sidebar nav.

Horizontal + vertical

Component

Breadcrumb

Chevron-separated breadcrumb trail with current page indicator.

1 variant

Component

Accordion

Show/hide content sections with plus/minus toggle and ARIA support.

1 variant · animated

Reference

Useful starting points.