/* =============================================================================
   base.css — the ground the instrument is painted on: one place for the palette
   and the layout metrics, and one region layout every later task inherits.

   Everything colour is a custom property on :root. Nothing below hard-codes a
   colour, so the impressionist repaint in task 002 is a change to this file and
   to the rules that read these properties, not a change to every control.

   This file holds the TOKENS and the structural reset only. The painted layer
   itself — ground, washes, impasto, section hues, typography, the responsive
   stack — lives in paint.css, which is loaded after this one.

   Every hue is declared twice: once as a hex, for anything that needs a literal
   colour (canvas, contrast maths), and once as three channels, so a wash can be
   a translucent version of a palette entry without a second hex to keep in sync:
       --sky: #9ec0cc;   --sky-rgb: 158 192 204;
   then   rgb(var(--sky-rgb) / 0.28).

   System font stacks only: no webfont, no network request.
   ========================================================================== */

:root {
  /* --- the palette ------------------------------------------------------- */
  --ground: #f2ead8; /* parchment */
  --ground-deep: #e7dcc4; /* the shaded edge of the sheet */
  --ground-lit: #f8f2e2; /* where the light falls on the sheet */
  --ink: #2b2722; /* charcoal */
  --ink-soft: #6b6153; /* charcoal, thinned */
  --ink-faint: #6f6553; /* charcoal, thinned twice — still clears AA on the ground */

  --sage: #8ba183;
  --sky: #9ec0cc; /* atrium sky */
  --rose: #c08a86; /* rose madder */
  --ochre: #d0a552;
  --lavender: #b0a3c2;

  --ground-rgb: 242 234 216;
  --ground-deep-rgb: 231 220 196;
  --ground-lit-rgb: 248 242 226;
  --ink-rgb: 43 39 34;
  --ink-soft-rgb: 107 97 83;
  --ink-faint-rgb: 111 101 83;
  --sage-rgb: 139 161 131;
  --sky-rgb: 158 192 204;
  --rose-rgb: 192 138 134;
  --ochre-rgb: 208 165 82;
  --lavender-rgb: 176 163 194;

  /* Deep variants, for a control that sits on its own hue. */
  --sage-deep: #5c6b55;
  --sky-deep: #5d8695;
  --rose-deep: #8e5c58;
  --ochre-deep: #8f6a1f;
  --lavender-deep: #6b5f7c;

  --sage-deep-rgb: 92 107 85;
  --sky-deep-rgb: 93 134 149;
  --rose-deep-rgb: 142 92 88;
  --ochre-deep-rgb: 143 106 31;
  --lavender-deep-rgb: 107 95 124;

  --panel: #f7f1e2;
  --panel-edge: #d8ccb0;
  --panel-shade: #ece2cb;
  --panel-rgb: 247 241 226;
  --panel-edge-rgb: 216 204 176;
  --panel-shade-rgb: 236 226 203;
  --focus: var(--ink);

  /* --- layout metrics ---------------------------------------------------- */
  --gap: 0.75rem;
  --gap-tight: 0.375rem;
  --radius: 0.5rem;
  --radius-paint: 0.3rem;
  --panel-pad: 0.7rem;
  --region-pad: 0.9rem;
  --hairline: 1px;
  --knob: 3.35rem;
  --knob-sm: 2.4rem;
  --fader-long: 5.5rem;
  --fader-short: 3.2rem;
  --fader-thick: 1.5rem;
  --key-w: 2.6rem;
  --key-h: 7rem;
  --key-ivory: #fbf7ec;
  --key-deep: #3a2f2c;

  /* --- type -------------------------------------------------------------- */
  /* Legends are a serif display face: the painterly signature. Readouts and
     everything else is a system sans. Both are local font stacks — the site
     must work with the network offline, so there is no webfont anywhere. */
  --font-legend: "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua",
    "Hoefler Text", Georgia, "Times New Roman", serif;
  --font-ui: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-readout: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --fs-micro: 0.6875rem;
  --fs-small: 0.8125rem;
  --fs-body: 0.9375rem;
  --fs-title: 1.25rem;
  --fs-display: 1.75rem;
}

/* Each control resolves its own hue through one property, so the skin in
   controls.css is written once. The channel forms are here because
   `rgb(var(--hue) / 0.4)` is invalid — a hex cannot be re-wrapped in rgb() — and
   a translucent wash of a hue is needed constantly. */
[data-hue="sage"] {
  --hue: var(--sage);
  --hue-deep: var(--sage-deep);
  --hue-rgb: var(--sage-rgb);
  --hue-deep-rgb: var(--sage-deep-rgb);
}
[data-hue="sky"] {
  --hue: var(--sky);
  --hue-deep: var(--sky-deep);
  --hue-rgb: var(--sky-rgb);
  --hue-deep-rgb: var(--sky-deep-rgb);
}
[data-hue="rose"] {
  --hue: var(--rose);
  --hue-deep: var(--rose-deep);
  --hue-rgb: var(--rose-rgb);
  --hue-deep-rgb: var(--rose-deep-rgb);
}
[data-hue="ochre"] {
  --hue: var(--ochre);
  --hue-deep: var(--ochre-deep);
  --hue-rgb: var(--ochre-rgb);
  --hue-deep-rgb: var(--ochre-deep-rgb);
}
[data-hue="lavender"] {
  --hue: var(--lavender);
  --hue-deep: var(--lavender-deep);
  --hue-rgb: var(--lavender-rgb);
  --hue-deep-rgb: var(--lavender-deep-rgb);
}

/* --- reset ---------------------------------------------------------------- */

*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 0;
  background: var(--ground);
  color: var(--ink);
  font-family: var(--font-ui);
  font-size: var(--fs-body);
  line-height: 1.45;
  -webkit-text-size-adjust: 100%;
}

h1,
h2,
h3,
p {
  margin: 0;
}

:where(button, select, input) {
  font: inherit;
  color: inherit;
}

/* One focus treatment for the whole instrument: a charcoal ring, always drawn
   above the paint, never removed. */
:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

.skip-link {
  position: absolute;
  left: -100vw;
  top: 0;
  z-index: 10;
  padding: 0.5rem 0.75rem;
  background: var(--ink);
  color: var(--ground);
  border-radius: 0 0 var(--radius) 0;
}

.skip-link:focus {
  left: 0;
}

/* --- the sheet ----------------------------------------------------------- */

.instrument {
  max-width: 96rem;
  margin: 0 auto;
  padding: var(--region-pad);
  display: flex;
  flex-direction: column;
  gap: var(--gap);
}

.masthead {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--gap);
  padding-bottom: var(--gap-tight);
  border-bottom: var(--hairline) solid var(--panel-edge);
}

.masthead__title {
  font-size: var(--fs-display);
  font-weight: 600;
  letter-spacing: 0.02em;
}

.masthead__sub {
  flex: 1 1 22rem;
  color: var(--ink-soft);
  font-size: var(--fs-small);
  max-width: 60ch;
}

.notice {
  padding: var(--panel-pad);
  border: var(--hairline) solid var(--panel-edge);
  border-radius: var(--radius);
  background: var(--panel);
}

/* --- regions ------------------------------------------------------------- */

.region {
  display: flex;
  flex-direction: column;
  gap: var(--gap-tight);
  padding: var(--region-pad);
  border: var(--hairline) solid var(--panel-edge);
  border-radius: var(--radius);
  background: var(--ground-deep);
}

.region__title {
  font-size: var(--fs-micro);
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-soft);
}

.region__panels {
  display: flex;
  flex-wrap: wrap;
  /* panels hug their contents: a stretched panel reads as an empty box, and the
     repaint in task 002 is what makes the rows line up */
  align-items: flex-start;
  gap: var(--gap);
}

/* The strip and the sequencer are the full width of the instrument. */
.region--strip,
.region--wide {
  grid-column: 1 / -1;
}

/* --- panels -------------------------------------------------------------- */

.panel {
  flex: 1 1 15rem;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: var(--gap-tight);
  padding: var(--panel-pad);
  border: var(--hairline) solid var(--panel-edge);
  border-radius: var(--radius);
  background: var(--panel);
}

.panel--matrix {
  flex: 1 1 40rem;
}

.panel--steps {
  flex: 1 1 32rem;
}

.region--kit .panel {
  flex: 1 1 11rem;
}

.panel__title {
  font-size: var(--fs-micro);
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-soft);
  padding-bottom: 0.2rem;
  border-bottom: var(--hairline) solid var(--panel-shade);
}

.panel__grid {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-start;
  gap: var(--gap);
}

.panel__caption {
  font-size: var(--fs-micro);
  color: var(--ink-faint);
  font-style: italic;
}

/* --- empty grids, laid out for the module that will fill them ------------- */

/* minmax(0, 1fr) rather than a floor: the eight columns have to fit inside the
   panel at a phone width, otherwise the grid overflows the page. */
.headgrid {
  display: grid;
  grid-template-columns: minmax(0, 4.25rem) repeat(8, minmax(0, 1fr));
  gap: 2px;
}

.headgrid__corner,
.headgrid__cell {
  min-height: 1.5rem;
  min-width: 0;
  background: var(--panel-shade);
  border-radius: 2px;
}

.headgrid__head {
  font-size: 0.625rem;
  color: var(--ink-soft);
  text-align: center;
  min-width: 0;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.headgrid__head--row {
  text-align: right;
  padding-right: 0.35rem;
}

.stepruler {
  display: grid;
  grid-auto-flow: column;
  grid-auto-columns: 1fr;
  gap: 2px;
}

.stepruler__step {
  font-family: var(--font-readout);
  font-size: var(--fs-micro);
  color: var(--ink-soft);
  text-align: center;
  padding: 0.2rem 0;
  background: var(--panel-shade);
  border-radius: 2px;
}

.stepruler__step:nth-child(4n + 1) {
  color: var(--ink);
  background: var(--panel-edge);
}

/* --- the keybed (layout only until the input module binds notes) ---------- */

.keybed {
  position: relative;
  height: var(--key-h);
  margin-top: var(--gap-tight);
  user-select: none;
}

.keybed__whites {
  display: flex;
  height: 100%;
  gap: 1px;
}

/* The black keys sit on the same 15-column grid as the whites, so a black key
   lands between the two whites it belongs to, 62% of a white key's width. */
.keybed__blacks {
  position: absolute;
  inset: 0 0 38% 0;
  display: grid;
  grid-template-columns: repeat(15, 1fr);
  gap: 1px;
  align-items: start;
}

.key--black {
  width: 62%;
  height: 100%;
  justify-self: center;
  /* A grid track is `minmax(auto, 1fr)`: before the free space is shared out, every
     track is floored at the min-content of the key on it — a nowrap note label, which
     is wider for C# than for D#. Those floors are unequal, so the leftover is shared
     on top of them and the tracks stop being equal, and a black key slides off the
     boundary between its two white keys. `min-width: 0` drops the floor and lets the
     29 columns be 29 equal shares, which is the whole of the placement this module
     documents: a black key is 62% of a white key, centred on the seam. Above the
     breakpoint the tracks are far wider than any label, so nothing moves. */
  min-width: 0;
  /* A painted key, not a machined one: warm charcoal with a rose wash over it,
     so the keybed is the darkest thing on the sheet and still part of the paint. */
  background: linear-gradient(rgb(var(--rose-rgb) / 0.62), var(--key-deep) 72%);
  border-radius: 0 0 3px 3px;
  box-shadow: 0 1px 2px rgb(var(--ink-rgb) / 0.3);
}

.key--black:nth-child(1) { grid-column: 1; }
.key--black:nth-child(2) { grid-column: 2; }
.key--black:nth-child(3) { grid-column: 4; }
.key--black:nth-child(4) { grid-column: 5; }
.key--black:nth-child(5) { grid-column: 6; }
.key--black:nth-child(6) { grid-column: 8; }
.key--black:nth-child(7) { grid-column: 9; }
.key--black:nth-child(8) { grid-column: 10; }
.key--black:nth-child(9) { grid-column: 12; }
.key--black:nth-child(10) { grid-column: 13; }

.key--white {
  flex: 1 1 0;
  min-width: 0;
  background: var(--key-ivory);
  border: var(--hairline) solid var(--panel-edge);
  border-radius: 0 0 3px 3px;
}

/* The responsive stack is in paint.css, at the one agreed breakpoint. */

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}