# Panel

The flat tonal container — and the component that carries `ground-role-split`. A Panel decides which ground its children sit on: `brand` (charcoal, both themes), `raised` (one tonal step up), `working` (the reading ground), or `feature` (resolved by theme: raised-brand on dark, paper on light).

```html
<div class="postie-panel postie-panel--raised">…</div>
<div class="postie-panel postie-panel--brand postie-brand postie-panel--tight">…agent card…</div>
<div class="postie-panel postie-panel--brand postie-brand postie-panel--loose">
  …hero…
  <div class="postie-panel postie-panel--feature">feature card — raised-brand on dark, paper tile on light, one markup</div>
  <div class="postie-panel postie-panel--working postie-working">always the working ground (the paper-preview)</div>
</div>
```

**When.** `raised` for any grouped content on the working surface (dashboard sections, the reply well, the "next step" card). `brand` for the hero, the auth brand panel, the agent card in the rail, the email masthead body. `feature` for the landing feature cards inside the brand hero: on dark they are the raised-brand step, on light they are paper tiles on the charcoal (BRIEF §4a) — same markup, no per-theme switch, no kit-level override. `working` when the tile must be the working ground in BOTH themes (the paper-preview).

**The mechanism.** `postie-brand` / `postie-working` on the same element set the `--postie-c-*` context, so every Button, Kicker, Badge and Field inside picks the right ink without a prop. A Panel with `tone="brand"` that forgets `.postie-brand` is the bug that puts oxblood text on charcoal — the reference markup always pairs them.

**Never.**
- Never a border, a shadow, a hairline under a title. Separation is the tonal step (tonal-step rule).
- Never a saturated fill as a panel ground — no oxblood panel, ever (never a large coloured ground).
- Never nest brand inside brand; the chrome is one step of charcoal, not a ramp.
- Never a soft gradient or a glow at the panel edge (brief `never`: wellness-serene, soft-glow).