GitHub Primer vs GOV.UK Design System
GitHub Primer / GOV.UK デザインシステム
Both sit in Platform Screen Languages, so the question is not what they belong to but how they behave. They are reached for with some of the same intent, which is where they get confused.
GitHub Primer
GitHub's design system for turning dense development workflows into shared rules for color, type, icons, spacing and components. It favors flow over decoration, keeping many states and actions in a small area without giving up accessibility or responsive behavior.
GOV.UK Design System
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The design language the UK government's Government Digital Service publishes and maintains for public services. Everything runs in one undecorated left aligned column set in GDS Transport, and the green button keeps square corners while carrying a darker green band along its bottom edge, dropping by exactly that depth when pressed. Whatever holds keyboard focus turns yellow with a black rule under it.
| GitHub Primer | GOV.UK Design System | |
|---|---|---|
| Era | 2017– | 2012– |
| Family | Platform Screen Languages | Platform Screen Languages |
| Kind | Style | Style |
| Cues | Neutral surfaces with blue links and restrained status colors / Octicons paired with short action labels / Thin borders separating lists, tabs and sidebars / Consistent steps of type and spacing even at high density | One undecorated left aligned column, with almost no boxes and no shadows / A green button with square corners and a darker green band along its bottom edge, which drops by that exact depth when pressed / Whatever holds keyboard focus turns yellow with a black rule drawn beneath it / Type sizes step coarsely through 48, 36, 24, 19 and 16px with nothing in between |
| Best used for | Developer SaaS and admin tools that must hold many states and actions on one screen · Keeping information density and accessibility consistent across product teams | Rebuilding a government or public service form as a single left aligned column asking one question per screen · Making the current focus position unmistakable for someone operating the service by keyboard alone |
| Type | Use one plain sans for body and labels; build hierarchy through weight and color. | One sans serif only, in five fixed sizes with nothing in between. Headings are bold and body text sits at 19px. |
| Composition | Separate lists, tabs and sidebars with fine rules and hold spacing to a small token set. | Hold the content to a single narrow column and align every element to one left rule. No multi column layouts and no boxes, because a horizontal rule is the only break between topics. |
| Material | Start from neutrals; reserve blue for links and semantic colors for success, warning and danger. | Colour is tied to meaning and never used decoratively. Buttons keep a corner radius of zero and gain their thickness from a band of their own darker shade along the bottom edge. The focus state is always yellow ground with a black underline. |
| Caution | Adding borders and tiny controls to look like GitHub only creates a cramped admin screen when the work has no clear priority. | Tidying the look by rounding button corners or thinning the borders on form inputs deletes the two signals this style relies on entirely, the pressable thickness and the position of focus. |