Contemplative precision.

Dark mode is the default state because the product simulates the nocturne environment of an observatory. A reading is a contemplative act; the parchment-toned text on a near-black background reduces eye strain across the 30-90 minutes a serious full-natal report asks of the reader.

Light mode exists — for daylight reading, for printed PDFs — but the product is authored for the dark. Decisions about colour, weight, and contrast all start from there.

Vertical spacing snaps to 8px increments (4 / 8 / 12 / 24 / 48 / 80). Layout columns use a 12-column framework with 24px gutters, capped at 1280px content width. The wheel — when it appears alongside text — sits on the same row baseline as the prose column. Generous Stack-LG spacing between sections gives the eye room to breathe; the information is dense, the page is not.

Depth is communicated by tonal layers and 1px strokes at 10-15% opacity, not by shadows or bevels. A surface-dark card sits on a darker primary background. Hover states shift border opacity or colour; elements rarely "lift" off the page. The interface should feel like an illuminated glass panel — flat, intentional, refined.

When you read "Mars 15°34' Cancer" in a chart, the digits land on the same column width whether you're reading degree, minute, or sign-degree. Inter's tabular-figures variant is enabled wherever numbers appear: the placements table, the orb column, the ephemeris graphs, the year-ahead transit cards. It is the smallest detail and the one that makes a chart feel professionally rendered rather than approximated.

Aspect lines distinguish on two axes — colour AND stroke pattern. Hard aspects (square, opposition) are solid and warmer-toned; soft aspects (trine, sextile) are dashed and cooler; conjunction is solid gold (the neutral fusion); minors are dotted and muted. A colour-blind reader gets the same information as a sighted one. This is a dual-channel encoding and it is non-negotiable.

Cards take a 12px corner radius — modern, sophisticated, not aggressive. Buttons sit at 8px — stable, reliable. Pills and chips use full-radius pills only for filterable attributes (aspect families, planet selectors). Circles are reserved for astronomy: planets, orbits, nodes. Sharpness is for instruments, roundness is for orbits.

A reading in Iovari is a tuple: (chart, strategy, model, prompt_version, ephemeris_version, generated_at). Save those fields and you can replay the reading bit-for-bit. We persist them on every reading row and surface them in the reading view's metadata rail. Old readings stay viewable when new prompt versions ship; new readings can be diffed against old ones to see how the engine has evolved.

Mysticism without precision is decoration. Precision without mysticism is a spreadsheet. Iovari holds both: the engine is verifiably correct, the voice is honestly contemplative. One serves the other. That's the design.