A design system is the set of decisions a site is built from: the colours, the text sizes, the spacing, what a button looks like, what happens when you hover it. We make those decisions once, show them on one page, lock them, and build every page from them. It is the step that makes a site match itself.
What gets decided?
The values first. Colours, each with a note on how it reads against the others, so text is always legible. A scale of text sizes, from a caption to a headline, that behaves on a phone and a wide screen. Spacing on one scale, so gaps are consistent rather than eyeballed. Motion, and what happens for people who have asked their device for less of it. The outline a keyboard user sees when they tab to a link.
Then the parts built from those values: buttons, links, headings, form fields, cards, the navigation, the footer, each with a one-sentence rule for how it behaves.
What is the kit page?
One web page that renders every part of the site from those values. Where there is a choice to make, two typefaces, two ways of treating the accent colour, the alternatives sit side by side on a switch, so you compare them by looking rather than by reading a description of them. It is the page Richard decides from, and it is a page you can open.
Before the kit is locked, a second set of eyes checks that what the kit page shows and what the token file says are the same thing. If they disagree, the step is not finished.
What does “lock it in” mean?
Richard says it, and the kit gets a version number and a date. From that moment every value in the build comes from the kit. No freehand pixel, no hex code typed into a page because it looked about right. A new value is a proposal into the kit first, then a change in the build.
If something later turns out to be wrong, the kit is unlocked with a line saying what was wrong and a new version, then re-locked. Never a silent edit. That discipline is what lets a site still look like itself after a year of changes.
Why bother, for a small site?
Because it is cheaper, not dearer. A locked kit means the third page costs less than the first, and the page you add next year matches the ones you have. It means legibility and keyboard focus were settled at the value level, so accessibility is built in rather than audited in. And it means “does this match?” always has an answer.
The size of the kit flexes with the job. A five-page site has a small kit. It still has one.