Hairline stat strip

<div class="demo">
  <p class="hss-cap">Reporting only — the figures are the whole job.</p>
  <div class="hss-strip four">
    <div class="hss-tile"><span class="hss-lbl">Documents</span><span class="hss-fig">1,482</span><span class="hss-sub">this period</span></div>
    <div class="hss-tile"><span class="hss-lbl">Median time</span><span class="hss-fig">3.2s</span><span class="hss-sub">last 24h</span></div>
    <div class="hss-tile"><span class="hss-lbl">Clean runs</span><span class="hss-fig">98.4%</span><span class="hss-sub">no retries</span></div>
    <div class="hss-tile"><span class="hss-lbl">Quality score</span><span class="hss-fig none" aria-label="No value">—</span><span class="hss-sub">not rated yet</span></div>
  </div>
  <p class="hss-cap">Same strip, working as the filter. Press a tile to narrow the list; press it again to clear.</p>
  <div class="hss-strip five" role="group" aria-label="Filter downloads by state">
    <button class="hss-tile" type="button" data-dl="All" aria-pressed="true"><span class="hss-lbl">All</span><span class="hss-fig">6</span><span class="hss-sub">downloads</span></button>
    <button class="hss-tile" type="button" data-dl="Queued" aria-pressed="false"><span class="hss-lbl">Queued</span><span class="hss-fig">2</span><span class="hss-sub">downloads</span></button>
    <button class="hss-tile" type="button" data-dl="Downloading" aria-pressed="false"><span class="hss-lbl">Downloading</span><span class="hss-fig">1</span><span class="hss-sub">downloads</span></button>
    <button class="hss-tile" type="button" data-dl="Done" aria-pressed="false"><span class="hss-lbl">Done</span><span class="hss-fig">2</span><span class="hss-sub">downloads</span></button>
    <button class="hss-tile" type="button" data-dl="Failed" aria-pressed="false"><span class="hss-lbl">Failed</span><span class="hss-fig">1</span><span class="hss-sub">downloads</span></button>
  </div>
  <ul class="dl-list">
    <li data-state="Done"><span>Bicycle drivetrain teardown</span><span class="dl-state">Done</span></li>
    <li data-state="Downloading"><span>Kiln firing, part three</span><span class="dl-state">Downloading</span></li>
    <li data-state="Queued"><span>Field recording — marsh at dawn</span><span class="dl-state">Queued</span></li>
    <li data-state="Done"><span>Lathe restoration, episode 12</span><span class="dl-state">Done</span></li>
    <li data-state="Failed"><span>Sourdough hydration tests</span><span class="dl-state">Failed</span></li>
    <li data-state="Queued"><span>Bookbinding: the long stitch</span><span class="dl-state">Queued</span></li>
  </ul>
  <p class="dl-status" id="dl-status" aria-live="polite">Showing all 6 downloads.</p>
</div>

Colors come from shared theme tokens — --surface, --ink, --border, --accent and friends — so this CSS carries no palette of its own. Use Runnable file to copy the tokens along with it.

.hss-strip {
  display: grid;
  gap: 1px;                       /* the hairline is the gap */
  background: var(--border);      /* container paints the line colour */
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  grid-template-columns: 1fr;
}
@container (min-width: 21rem) { .hss-strip { grid-template-columns: repeat(2, 1fr); } }
@container (min-width: 42rem) { .hss-strip { grid-template-columns: repeat(4, 1fr); } }

.hss-tile { background: var(--surface); padding: 0.9rem 1rem; min-width: 0; }
.hss-lbl {
  font: 0.8125rem/1.3 ui-monospace, monospace;
  text-transform: uppercase;
  color: var(--dim);
  overflow-wrap: anywhere;        /* long labels wrap instead of overflowing */
}
.hss-fig { font-size: 1.6rem; font-weight: 700; font-variant-numeric: tabular-nums; }
.hss-fig.none { color: var(--dim); font-weight: 400; }

button.hss-tile[aria-pressed="true"] {
  background: color-mix(in srgb, var(--accent) 14%, var(--surface));
}

const tiles = document.querySelectorAll("[data-dl]");
tiles.forEach((tile) => tile.addEventListener("click", () => {
  const state = tile.dataset.dl;
  const on = tile.getAttribute("aria-pressed") !== "true" && state !== "All";
  tiles.forEach((other) => other.setAttribute("aria-pressed",
    String(on ? other === tile : other.dataset.dl === "All")));
  // counts on the tiles come from the unfiltered set, so they never change here
}));

The full prompt continues with sections on pinning column counts, tile anatomy, two rules of honesty (render a missing value as a dimmed em dash; keep units with the number), the filter form, computing counts from the unfiltered set, and using aria-pressed rather than tab roles.