* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  background: #111827;
  color: #f9fafb;
  min-height: 100vh;
}

.container {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
}

.card {
  width: 100%;
  max-width: 980px;
  background: #1f2937;
  border: 1px solid #374151;
  border-radius: 16px;
  padding: 28px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
}

h1 {
  margin: 0 0 8px;
  font-size: 2rem;
}

.subtitle {
  margin: 0 0 24px;
  color: #cbd5e1;
}

.controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 16px;
  margin-bottom: 24px;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

label {
  font-size: 0.95rem;
  color: #d1d5db;
}

select,
button,
input[type="range"] {
  height: 44px;
  border-radius: 10px;
  border: 1px solid #4b5563;
  font-size: 1rem;
}

select {
  padding: 0 12px;
  background: #111827;
  color: #f9fafb;
}

input[type="range"] {
  appearance: none;
  background: #111827;
  padding: 0 10px;
  cursor: pointer;
}

input[type="range"]::-webkit-slider-runnable-track {
  height: 8px;
  background: #374151;
  border-radius: 999px;
}

input[type="range"]::-webkit-slider-thumb {
  appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: #60a5fa;
  margin-top: -5px;
  border: none;
}

input[type="range"]::-moz-range-track {
  height: 8px;
  background: #374151;
  border-radius: 999px;
}

input[type="range"]::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: #60a5fa;
  border: none;
}

button {
  padding: 0 16px;
  background: #2563eb;
  color: white;
  cursor: pointer;
  font-weight: 600;
}

button:hover {
  background: #1d4ed8;
}

.button-wrap {
  justify-content: end;
}

.status {
  min-height: 24px;
  margin-bottom: 16px;
  color: #fca5a5;
}

.result {
  border-top: 1px solid #374151;
  padding-top: 20px;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 18px;
}

.section-card {
  background: rgba(17, 24, 39, 0.55);
  border: 1px solid #374151;
  border-radius: 14px;
  padding: 18px;
}

.section-card h2 {
  margin: 0 0 16px;
  font-size: 1.15rem;
}

.chorus-card {
  border-color: #4f46e5;
  box-shadow: inset 0 0 0 1px rgba(99, 102, 241, 0.15);
}

.result-block + .result-block {
  margin-top: 18px;
}

.label {
  display: block;
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: #93c5fd;
  margin-bottom: 6px;
}

.value {
  font-size: 1.05rem;
  line-height: 1.5;
}

.chords {
  font-size: 1.35rem;
  font-weight: 700;
  color: #fbbf24;
}

.hidden {
  display: none;
}

#playBtn,
#playSongBtn {
  background: #059669;
}

#playBtn:hover,
#playSongBtn:hover {
  background: #047857;
}

#stopBtn {
  background: #dc2626;
}

#stopBtn:hover {
  background: #b91c1c;
}

#loopBtn {
  background: #7c3aed;
}

#loopBtn:hover {
  background: #6d28d9;
}

#regenChorusBtn {
  background: #0f766e;
}

#regenChorusBtn:hover {
  background: #115e59;
}