Grey is the main colour. Context series use mm-text-3 or mm-rule. The one series that matters uses mm-primary or mm-info, and that is the only colour on the chart.
Label lines and bars directly at their ends in 13px mono. Avoid legends.
Range-frame axes span only the data's minimum to maximum, with endpoint values labelled. At most three 1px dotted gridlines, outward 4px ticks, no chart box.
Bars have square or 1px tops. Area fills are a flat 8–12% tint, never a gradient. Hatch estimated or stale data.
Sparklines are word-sized (64×16) with the last point marked by a 3px dot and its value printed in mono beside it.
Annotate like a technical drawing: a 1px leader line with a dot terminal and a mono caption, and dimension brackets for time ranges such as an incident window.
Use small multiples for per-source or per-domain health, with a shared scale, laid out like map sheets and labelled with a sentence-case caption.
The signature chart is a contour or isoline density view (lineage density, query heat, usage) in mm-contour with 4–6 bands, the heaviest as an index contour in mm-contour-index.
Categorical status colours sit at similar lightness so no category shouts.
Structured values (metadata, JSON) use one text face and ink for every value; only the keys are mono, because people copy them. No colour by type. True and false read "Yes" and "No", a missing value reads "Not set", lists of plain values read inline, comma separated, and only objects fold open (clicking anywhere on the row). The raw JSON is one click away.
Tooltips are square-cornered and ink-filled (mm-tooltip), with mono key/value pairs and tabular numbers, no blur, shown instantly.