/* ---------- Tokens ---------- */
:root {
  color-scheme: light dark;
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  line-height: 1.4;

  /* Light theme (default) */
  --bg: #fafafa;
  --surface: #fff;
  --surface-soft: #f4f5f7;
  --text: #111;
  --muted: #666;
  --border: #d0d0d0;
  --border-strong: #111;
  --accent: #2563eb;
  --track: #e0e0e0;
  --radius: 10px;
  --radius-lg: 14px;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.04), 0 1px 3px rgba(0, 0, 0, 0.06);

  --degree-0:  #5858fe;  /* Do  */
  --degree-1:  #abff56;  /* Ra  */
  --degree-2:  #ff59ff;  /* Re  */
  --degree-3:  #58ffac;  /* Me  */
  --degree-4:  #ff5959;  /* Mi  */
  --degree-5:  #5affff;  /* Fa  */
  --degree-6:  #ffff5a;  /* Fi  */
  --degree-7:  #ad59fe;  /* Sol */
  --degree-8:  #59fe59;  /* Le  */
  --degree-9:  #ff59ac;  /* La  */
  --degree-10: #58ffff;  /* Te  */
  --degree-11: #ffac59;  /* Ti  */
}

/* Dark theme palette */
:root[data-theme="dark"],
:root:not([data-theme="light"]) {
  /* defaults stay; OS-dark and explicit-dark applied below */
}
:root[data-theme="dark"] { color-scheme: dark; }
:root[data-theme="light"] { color-scheme: light; }

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) { color-scheme: dark; }
  :root:not([data-theme="light"]),
  :root[data-theme="dark"] { /* combined ruleset below */ }
}

/* Apply dark variables: explicit dark, OR (OS dark AND not forced light) */
:root[data-theme="dark"] {
  --bg: #0f1115;
  --surface: #1a1d23;
  --surface-soft: #232730;
  --text: #ececec;
  --muted: #9aa3b2;
  --border: #353a45;
  --border-strong: #ececec;
  --accent: #60a5fa;
  --track: #2a2f39;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 1px 3px rgba(0, 0, 0, 0.5);
  --degree-0:  #ff6b6b;
  --degree-1:  #ff9f43;
  --degree-2:  #ffd166;
  --degree-3:  #a8d957;
  --degree-4:  #6ed27a;
  --degree-5:  #4dd0c1;
  --degree-6:  #5ed3e0;
  --degree-7:  #6aa9ff;
  --degree-8:  #8c9bff;
  --degree-9:  #b794f4;
  --degree-10: #d68bff;
  --degree-11: #ff7eb6;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f1115;
    --surface: #1a1d23;
    --surface-soft: #232730;
    --text: #ececec;
    --muted: #9aa3b2;
    --border: #353a45;
    --border-strong: #ececec;
    --accent: #60a5fa;
    --track: #2a2f39;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 1px 3px rgba(0, 0, 0, 0.5);
    --degree-0:  #5858fe;  /* Do  */
    --degree-1:  #abff56;  /* Ra  */
    --degree-2:  #ff59ff;  /* Re  */
    --degree-3:  #58ffac;  /* Me  */
    --degree-4:  #ff5959;  /* Mi  */
    --degree-5:  #5affff;  /* Fa  */
    --degree-6:  #ffff5a;  /* Fi  */
    --degree-7:  #ad59fe;  /* Sol */
    --degree-8:  #59fe59;  /* Le  */
    --degree-9:  #ff59ac;  /* La  */
    --degree-10: #58ffff;  /* Te  */
    --degree-11: #ffac59;  /* Ti  */
  }
}

/* ---------- Base ---------- */
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--text); }
main {
  max-width: 640px;
  margin: 1rem auto;
  padding: 0 0.9rem 2rem;
  display: grid;
  gap: 1rem;
}
h1 {
  font-size: 1.25rem;
  margin: 0;
  letter-spacing: 0.01em;
}
.app-header {
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  margin-top: 0.25rem;
}
.icon-btn {
  position: absolute;
  right: 0;
  width: 2.1rem;
  height: 2.1rem;
  padding: 0;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.intro {
  margin: -0.25rem 0 0;
  text-align: center;
  max-width: 38rem;
  align-self: center;
  line-height: 1.5;
}
.intro span[aria-hidden] { font-weight: 700; color: var(--text); }

/* Inline SVG icons (Lucide, ISC license) inside buttons. */
.icon { width: 1.05rem; height: 1.05rem; flex: none; stroke: currentColor; }
.icon-btn .icon { width: 1.15rem; height: 1.15rem; }
.icon-text { display: inline-flex; align-items: center; gap: 0.4rem; }

/* ---------- Form controls ---------- */
input, select, button { font: inherit; color: inherit; }
input[type="number"], select {
  padding: 0.32rem 0.48rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}
input[type="number"] { width: 4.2rem; }
button {
  border: 1px solid var(--border);
  background: var(--surface);
  border-radius: 999px;
  padding: 0.36rem 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 120ms;
}
button:hover:not(:disabled) { background: var(--surface-soft); }
button:disabled { opacity: 0.45; cursor: not-allowed; }
button.primary {
  background: var(--text);
  color: var(--bg);
  border-color: var(--text);
}
button.primary:hover:not(:disabled) { filter: brightness(1.15); }
button:focus-visible,
input:focus-visible,
select:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}
label { font-weight: 600; font-size: 0.85rem; }
.muted { color: var(--muted); font-size: 0.78rem; }

/* ---------- Card / section ---------- */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
  padding: 0.9rem 1rem;
  display: grid;
  gap: 0.85rem;
}
.card h2 {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  margin: 0;
  font-weight: 700;
}
.row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 1rem;
}
.row.center { justify-content: center; }
.field { display: inline-flex; align-items: center; gap: 0.4rem; }
.field-stack { display: grid; gap: 0.5rem; }
.field-stack .field-row { display: flex; align-items: center; gap: 0.55rem; }
.field-stack input[type="range"] { flex: 1; min-width: 0; }
.field-stack .value { min-width: 3.2rem; text-align: right; font-variant-numeric: tabular-nums; }
.field-stack > .field-row > label:first-child { min-width: 4.5rem; }

/* ---------- Segmented control ----------
 * Used for choosing among a small set of discrete values (tonic, note count).
 */
.segmented {
  display: grid;
  grid-auto-flow: column;
  grid-auto-columns: 1fr;
  gap: 4px;
  background: var(--surface-soft);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 3px;
  width: 100%;
}
.segmented button {
  border: none;
  background: transparent;
  border-radius: 999px;
  padding: 0.3rem 0.2rem;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--muted);
  cursor: pointer;
  min-width: 0;
  transition: background 120ms, color 120ms;
}
.segmented button:hover { color: var(--text); background: var(--surface); }
.segmented button[aria-checked="true"] {
  background: var(--accent);
  color: white;
}
.field-row.stacked { flex-direction: column; align-items: stretch; gap: 0.35rem; }
.field-row.stacked > label { color: var(--muted); font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; }

/* ---------- Vocal range (dual slider) ----------
 * Layout: thumb labels sit in their own row above the slider track so they
 * are never obscured by the thumbs themselves.
 */
.range {
  display: grid;
  gap: 0.35rem;
}
.range-track {
  position: relative;
  /* Top space (1.4rem) reserved for the thumb labels; bottom space holds
     the slider track + thumbs. */
  height: 2.8rem;
  padding-top: 1.4rem;
  --range-start: 0%;
  --range-end: 100%;
}
.range-track::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 50%;
  transform: translateY(50%);
  /* Center the track within the lower half (below the labels). */
  top: auto;
  margin-bottom: -0.7rem;
  height: 4px;
  border-radius: 999px;
  background:
    linear-gradient(to right,
      var(--track) 0%,
      var(--track) var(--range-start),
      var(--accent) var(--range-start),
      var(--accent) var(--range-end),
      var(--track) var(--range-end),
      var(--track) 100%);
}
.range-track input[type="range"] {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1.4rem;
  width: 100%;
  margin: 0;
  pointer-events: none;
  -webkit-appearance: none;
  appearance: none;
  background: none;
}
.range-track input[type="range"]::-webkit-slider-thumb,
.range-track input[type="range"]::-moz-range-thumb {
  pointer-events: auto;
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  border: 1.5px solid var(--border-strong);
  background: var(--surface);
  cursor: pointer;
  box-shadow: var(--shadow);
}
.range-thumb-label {
  position: absolute;
  top: 0;
  transform: translateX(-50%);
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--muted);
  background: var(--surface);
  padding: 0 0.2rem;
  border-radius: 4px;
  pointer-events: none;
  white-space: nowrap;
}

/* ---------- Scale degrees ---------- */
.scale {
  display: grid;
  gap: 0.55rem;
  justify-items: center;
}
.scale-presets {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  justify-content: center;
}
.scale-presets button {
  padding: 0.22rem 0.6rem;
  font-size: 0.78rem;
}
.degrees {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.35rem 0.7rem;
}
.degrees label {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  font-weight: 700;
  font-size: 0.85rem;
  white-space: nowrap;
  user-select: none;
}
.degrees input { margin: 0; }

/* ---------- Melody display ---------- */
.melody {
  font-size: 1.45rem;
  font-weight: 700;
  letter-spacing: 0.015em;
  line-height: 1.55;
  min-height: 2.2em;
  text-align: center;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 0.9rem 1rem;
  background: var(--surface);
}
.melody .interval, .melody .note { white-space: nowrap; }
.melody.placeholder { font-weight: 400; font-style: italic; color: var(--muted); }
.melody .tonic-note { color: var(--degree-0); }
.melody .interval { color: var(--muted); margin: 0 0.05em; font-weight: 500; }
.melody .note {
  display: inline-block;
  padding: 0 0.18em;
  border-radius: 6px;
  transition: background-color 80ms linear, transform 80ms ease-out;
}
.melody .note.playing {
  background: var(--surface-soft);
  box-shadow: inset 0 -2px 0 currentColor;
  transform: translateY(-1px);
}

/* ---------- Degree colors (shared by checkbox labels & melody output) ---------- */
.deg-do  { color: var(--degree-0); }
.deg-ra  { color: var(--degree-1); }
.deg-re  { color: var(--degree-2); }
.deg-me  { color: var(--degree-3); }
.deg-mi  { color: var(--degree-4); }
.deg-fa  { color: var(--degree-5); }
.deg-fi  { color: var(--degree-6); }
.deg-sol { color: var(--degree-7); }
.deg-le  { color: var(--degree-8); }
.deg-la  { color: var(--degree-9); }
.deg-te  { color: var(--degree-10); }
.deg-ti  { color: var(--degree-11); }

/* ---------- Playback ---------- */
.playback { display: flex; flex-wrap: wrap; gap: 0.5rem; justify-content: center; }
#status { width: 100%; text-align: center; min-height: 1em; }

/* ---------- Mobile ---------- */
@media (max-width: 640px) {
  main { margin: 0.5rem auto; padding: 0 0.6rem 1.2rem; gap: 0.75rem; }
  .card { padding: 0.75rem 0.85rem; gap: 0.7rem; }
  .melody { font-size: 1.2rem; padding: 0.75rem; }
  .row { gap: 0.4rem 0.7rem; }
  .playback button { flex: 1 1 auto; }
}