/* ===== Tokens =====
   Subject: a tabletop instrument panel — tuner, keys, brass fittings.
   Palette: near-black walnut case, ivory keys, brass fittings, teal indicator.
*/
:root{
  --bg: #14120e;
  --panel: #1c1913;
  --panel-raised: #211d16;
  --ivory: #f3ecdb;
  --ivory-dim: #b8b0a0;
  --brass: #c9a24b;
  --brass-bright: #e4bd66;
  --brass-dim: #7c6636;
  --teal: #4f8b7c;
  --rust: #b5533c;
  --line: rgba(243,236,219,0.12);
  --line-strong: rgba(243,236,219,0.22);
  --shadow: 0 12px 30px rgba(0,0,0,0.45);

  --font-display: "Fraunces", serif;
  --font-body: "Inter", sans-serif;
  --font-mono: "JetBrains Mono", monospace;

  --radius: 10px;
}

*{ box-sizing: border-box; }

html, body{
  margin:0;
  padding:0;
  background: var(--bg);
  color: var(--ivory);
  font-family: var(--font-body);
  min-height: 100vh;
}

body{
  background-image:
    radial-gradient(ellipse at top, rgba(201,162,75,0.06), transparent 60%),
    repeating-linear-gradient(180deg, rgba(255,255,255,0.012) 0px, rgba(255,255,255,0.012) 1px, transparent 1px, transparent 3px);
}

.sr-only{
  position:absolute; width:1px; height:1px; padding:0; margin:-1px;
  overflow:hidden; clip:rect(0,0,0,0); white-space:nowrap; border:0;
}

/* ===== Brand strip ===== */
.rack{
  max-width: 1180px;
  margin: 0 auto;
  padding: 28px 20px 40px;
}

.rack__brand{
  display:flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 22px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--line);
}

.rack__brand-mark{
  color: var(--brass);
  font-size: 1.6rem;
  line-height: 1;
}

.rack__brand h1{
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.5rem;
  letter-spacing: 0.01em;
  margin: 0;
  color: var(--ivory);
}

.rack__tagline{
  font-size: 0.82rem;
  color: var(--ivory-dim);
  font-style: italic;
  font-family: var(--font-display);
  margin-left: 4px;
}

/* ===== Grid ===== */
.app-grid{
  display: grid;
  grid-template-columns: 1fr 1fr;
  grid-template-areas:
    "settings tuner"
    "exercise exercise";
  gap: 16px;
}

@media (max-width: 760px){
  .app-grid{
    grid-template-columns: 1fr;
    grid-template-areas:
      "settings"
      "tuner"
      "exercise";
  }
}

.panel--settings{ grid-area: settings; }
.panel--tuner{ grid-area: tuner; }
.panel--exercise{ grid-area: exercise; }

/* ===== Panel shell ===== */
.panel{
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px 22px;
  box-shadow: var(--shadow);
}

.panel h2{
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  margin: 0 0 16px;
  color: var(--brass-bright);
  display:flex;
  align-items: center;
  gap: 10px;
}

.panel__index{
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--brass-dim);
  border: 1px solid var(--line-strong);
  border-radius: 4px;
  padding: 1px 6px;
}

/* ===== Settings fields ===== */
.field{
  margin-bottom: 16px;
}
.field:last-child{ margin-bottom: 0; }

.field label{
  display:block;
  font-size: 0.82rem;
  color: var(--ivory-dim);
  margin-bottom: 8px;
}

.field--row{
  display:flex;
  align-items:center;
  justify-content: space-between;
  gap: 12px;
}
.field--row label{ margin-bottom:0; flex:1; }

input[type="range"]{
  -webkit-appearance:none;
  width:100%;
  height: 3px;
  background: var(--line-strong);
  border-radius: 2px;
  outline: none;
}
input[type="range"]::-webkit-slider-thumb{
  -webkit-appearance:none;
  width:14px; height:14px;
  border-radius:50%;
  background: var(--brass);
  cursor:pointer;
  border: 2px solid var(--panel);
  box-shadow: 0 0 0 1px var(--brass-dim);
}
input[type="range"]::-moz-range-thumb{
  width:14px; height:14px;
  border-radius:50%;
  background: var(--brass);
  cursor:pointer;
  border: 2px solid var(--panel);
}

select{
  width:100%;
  background: var(--panel-raised);
  color: var(--ivory);
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  padding: 8px 10px;
  font-family: var(--font-body);
  font-size: 0.88rem;
}

input[type="checkbox"]{
  width: 34px; height: 18px;
  appearance: none; -webkit-appearance:none;
  background: var(--line-strong);
  border-radius: 10px;
  position: relative;
  cursor: pointer;
  flex-shrink: 0;
  transition: background 0.15s ease;
}
input[type="checkbox"]::before{
  content:"";
  position:absolute;
  top:2px; left:2px;
  width:14px; height:14px;
  background: var(--ivory-dim);
  border-radius:50%;
  transition: transform 0.15s ease, background 0.15s ease;
}
input[type="checkbox"]:checked{ background: var(--brass-dim); }
input[type="checkbox"]:checked::before{
  transform: translateX(16px);
  background: var(--brass-bright);
}

/* ===== Tuner (signature element) ===== */
.tuner{
  display:flex;
  flex-direction: column;
  align-items:center;
  gap: 12px;
}

.tuner__dial{
  width: 100%;
  max-width: 260px;
  height: auto;
}

.tuner__needle{
  stroke: var(--brass);
  stroke-width: 2.5;
  stroke-linecap: round;
  transform-origin: 110px 120px;
  transform: rotate(0deg);
  transition: transform 0.09s ease-out, stroke 0.15s ease;
}

.tuner__readout{
  display:flex;
  align-items: baseline;
  gap: 10px;
  font-family: var(--font-mono);
}

.tuner__note{
  font-family: var(--font-display);
  font-size: 1.6rem;
  font-weight: 600;
  color: var(--ivory);
  min-width: 2.4ch;
  text-align:center;
}

.tuner__freq{
  font-size: 0.8rem;
  color: var(--ivory-dim);
}

.tuner__cents{
  font-size: 0.8rem;
  color: var(--brass);
  min-width: 4ch;
}

.tuner__status{
  font-size: 0.76rem;
  color: var(--ivory-dim);
  text-align:center;
  margin: 0;
  max-width: 30ch;
}

/* ===== Buttons ===== */
.btn{
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 0.85rem;
  border-radius: 7px;
  border: 1px solid transparent;
  padding: 10px 18px;
  cursor: pointer;
  transition: all 0.12s ease;
}
.btn:disabled{ opacity: 0.4; cursor: not-allowed; }

.btn--ghost{
  background: transparent;
  border-color: var(--line-strong);
  color: var(--ivory);
}
.btn--ghost:not(:disabled):hover{ border-color: var(--brass); color: var(--brass-bright); }

.btn--primary{
  background: var(--brass);
  color: #1c1913;
  width: 100%;
  margin-top: 18px;
  padding: 13px;
  font-size: 0.95rem;
  letter-spacing: 0.02em;
}
.btn--primary:not(:disabled):hover{ background: var(--brass-bright); }
.btn--primary:not(:disabled):active{ transform: scale(0.99); }

/* ===== Carousel ===== */
.carousel{
  display:flex;
  align-items:center;
  gap: 10px;
}

.carousel__arrow{
  background: transparent;
  border: 1px solid var(--line-strong);
  color: var(--ivory-dim);
  font-size: 1.3rem;
  line-height: 1;
  width: 34px; height: 34px;
  border-radius: 50%;
  cursor: pointer;
  flex-shrink: 0;
  transition: all 0.12s ease;
}
.carousel__arrow:hover{ color: var(--brass-bright); border-color: var(--brass); }

.carousel__viewport{
  overflow: hidden;
  flex: 1;
}

.carousel__track{
  display:flex;
  transition: transform 0.35s cubic-bezier(.4,0,.2,1);
}

.exercise-card{
  min-width: 100%;
  padding: 4px 8px;
}

.exercise-card__eyebrow{
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--brass);
}

.exercise-card h3{
  font-family: var(--font-display);
  font-size: 1.4rem;
  font-weight: 600;
  margin: 6px 0 8px;
}

.exercise-card p{
  color: var(--ivory-dim);
  font-size: 0.9rem;
  line-height: 1.55;
  margin: 0 0 14px;
  max-width: 60ch;
}

.exercise-card--soon p{ margin-bottom: 6px; }

.exercise-card__soon{
  display:inline-block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--ivory-dim);
  border: 1px dashed var(--line-strong);
  border-radius: 5px;
  padding: 4px 10px;
  margin-top: 4px;
}

.exercise-card__result{
  font-family: var(--font-mono);
  background: var(--panel-raised);
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  padding: 10px 14px;
  margin-bottom: 14px;
  color: var(--teal);
  font-size: 0.95rem;
}

.exercise-card__controls{
  display:flex;
  gap: 10px;
}

.carousel__dots{
  display:flex;
  justify-content:center;
  gap: 8px;
  margin-top: 14px;
}

.carousel__dots button{
  width: 7px; height: 7px;
  border-radius: 50%;
  background: var(--line-strong);
  border: none;
  cursor:pointer;
  padding: 0;
}
.carousel__dots button[aria-current="true"]{ background: var(--brass); }

/* ===== Piano ===== */
.panel--piano{
  margin-top: 16px;
  padding: 16px 16px 0;
  overflow: hidden;
}

.piano__scroll{
  overflow-x: auto;
  overflow-y: hidden;
  padding-bottom: 16px;
}

.piano{
  position: relative;
  height: 150px;
  display: flex;
  width: max-content;
  margin: 0 auto;
}

.key{
  position: relative;
  border: 1px solid #0b0a07;
  border-radius: 0 0 5px 5px;
  cursor: pointer;
  user-select: none;
  transition: background 0.06s ease;
  display:flex;
  align-items:flex-end;
  justify-content:center;
  padding-bottom: 8px;
}

.key--white{
  width: 34px;
  height: 150px;
  background: linear-gradient(180deg, var(--ivory) 0%, #e3dac2 100%);
  z-index: 1;
}
.key--white.is-active,
.key--white:active{ background: linear-gradient(180deg, var(--brass-bright) 0%, var(--brass) 100%); }

.key--white.is-root::after{
  content:"";
  position:absolute;
  bottom: 6px;
  width: 5px; height: 5px;
  border-radius: 50%;
  background: var(--rust);
}

.key--black{
  width: 21px;
  height: 92px;
  background: linear-gradient(180deg, #2b2620 0%, #0e0c09 100%);
  margin-left: -11px;
  margin-right: -11px;
  z-index: 2;
  border-radius: 0 0 4px 4px;
}
.key--black.is-active,
.key--black:active{ background: linear-gradient(180deg, var(--brass) 0%, var(--brass-dim) 100%); }

.key__label{
  font-family: var(--font-mono);
  font-size: 0.6rem;
  color: rgba(20,18,14,0.55);
  pointer-events:none;
}
.key--black .key__label{ color: rgba(243,236,219,0.55); }