.spectral-section {
  margin-top: 2rem;
  padding: 32px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 12px;
}

.spectral-header h3 { color: var(--teal-dark); font-size: 1.75rem; margin-bottom: 0.5rem; }
.spectral-subtitle { color: var(--ink-soft); font-size: 1rem; margin-bottom: 1.5rem; }

/* Controls & Buttons */
.spectral-controls {
  display: flex;
  flex-direction: column;
  gap: 24px;
  margin-bottom: 32px;
  padding: 24px;
  background: var(--white);
  border-radius: 8px;
  border: 1px solid var(--line);
}

.spec-ctrl-row { display: flex; align-items: center; gap: 16px; flex-wrap: wrap; }
.spec-btn {
  background: var(--teal); color: var(--white); font-family: inherit; font-size: 0.9rem; font-weight: 800; letter-spacing: 0.04em; text-transform: uppercase;
  padding: 12px 24px; border-radius: 8px; border: none; cursor: pointer; box-shadow: 0 4px 12px rgba(4, 124, 118, 0.2); transition: transform 0.15s, background 0.15s;
}
.spec-btn:hover:not(:disabled) { background: var(--teal-dark); transform: translateY(-1px); }
.spec-btn:disabled { background: var(--mist); color: var(--ink-soft); box-shadow: none; cursor: not-allowed; }
.spec-status { font-family: 'DM Mono', monospace; color: var(--teal); font-weight: 600; font-size: 0.85rem; }

/* Sliders */
.spec-sliders { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 24px; }
.spec-slider-group { display: flex; flex-direction: column; gap: 12px; }
.spec-slider-group label { color: var(--ink); font-size: 0.95rem; display: flex; justify-content: space-between; align-items: center; }
.spec-ctrl-val { color: var(--teal); background: var(--mist); padding: 4px 8px; border-radius: 4px; font-size: 0.85rem; }
.spec-slider-group input[type="range"] { width: 100%; height: 6px; background: var(--mist); border-radius: 3px; outline: none; border: none; }
.spec-slider-group input[type="range"]::-webkit-slider-thumb { -webkit-appearance: none; width: 20px; height: 20px; border-radius: 50%; background: var(--teal); cursor: pointer; transition: transform 0.1s; }
.spec-slider-group input[type="range"]::-webkit-slider-thumb:hover { transform: scale(1.15); }

/* ── Custom dual-handle range slider ───────────────────── */
.dual-range-slider {
  position: relative;
  width: 100%;
  height: 36px;
  display: flex;
  align-items: center;
  user-select: none;
  -webkit-user-select: none;
  touch-action: none;
}

.drs-track {
  position: absolute;
  left: 0; right: 0;
  height: 5px;
  border-radius: 3px;
  background: var(--mist);
  cursor: pointer;
}

.drs-fill {
  position: absolute;
  top: 0; height: 100%;
  border-radius: 3px;
  background: var(--teal);
  pointer-events: none;
}

.drs-handle {
  position: absolute;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--white);
  border: 2px solid var(--teal);
  box-shadow: 0 1px 4px rgba(0,0,0,0.25);
  cursor: grab;
  z-index: 2;
  transition: box-shadow 0.15s, transform 0.1s;
  outline: none;
}

.drs-handle:hover {
  box-shadow: 0 0 0 6px rgba(4,124,118,0.18), 0 1px 4px rgba(0,0,0,0.25);
}

.drs-handle:focus-visible {
  box-shadow: 0 0 0 6px rgba(4,124,118,0.35), 0 1px 4px rgba(0,0,0,0.25);
}

.drs-handle--active {
  cursor: grabbing;
  transform: translate(-50%, -50%) scale(1.18);
  box-shadow: 0 0 0 7px rgba(4,124,118,0.22), 0 2px 6px rgba(0,0,0,0.3);
  z-index: 3;
}

.drs-handle-label {
  position: absolute;
  bottom: calc(100% + 7px);
  left: 50%;
  transform: translateX(-50%);
  font-size: 10px;
  font-weight: 600;
  font-family: 'DM Mono', monospace;
  color: var(--white);
  background: var(--teal-dark);
  border-radius: 4px;
  padding: 2px 6px;
  white-space: nowrap;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.15s;
}

.drs-handle:hover .drs-handle-label,
.drs-handle:focus-visible .drs-handle-label,
.drs-handle--active .drs-handle-label {
  opacity: 1;
}

/* 2x2 Heatmap Grid Layout */
.spectral-grid { 
  display: grid; 
  grid-template-columns: repeat(2, 1fr); 
  gap: 24px; 
}

/* Fallback breakpoint to 1 column for smaller viewports */
@media (max-width: 800px) {
  .spectral-grid { grid-template-columns: 1fr; }
}

.spec-panel { background: var(--white); border: 1px solid var(--line); border-radius: 12px; padding: 16px; box-shadow: 0 8px 24px rgba(20, 32, 31, 0.06); display: flex; flex-direction: column; gap: 12px; }
.spec-panel-label { font-size: 0.85rem; font-weight: 800; color: var(--ink-soft); text-transform: uppercase; letter-spacing: 0.05em; }

/* Canvas Layout Wrapper */
.spec-canvas-wrap { 
  display: flex; 
  gap: 12px; 
  background: var(--ink); 
  padding: 12px; 
  border-radius: 8px; 
  align-items: stretch; /* Stretches colorbars and ticks to match heatmap height automatically */
}

.spec-canvas-wrap canvas:first-child { 
  flex: 1; 
  border-radius: 4px; 
  image-rendering: pixelated; 
  width: 100%; 
  height: auto;       /* Tells browser to compute correct height based on canvas aspect ratio */
  display: block;     /* Eliminates default inline baseline spacing gaps underneath canvas */
}

.colorbar-canvas { 
  width: 20px !important; 
  height: auto; 
  display: block; 
  border-radius: 4px; 
}

/* Side Aligned Colorbar Axis Ticks */
.spec-axis-hz { 
  display: flex; 
  flex-direction: column; 
  justify-content: space-between; 
  font-family: 'DM Mono', monospace; 
  font-size: 0.75rem; 
  color: rgba(255, 255, 255, 0.8); 
  font-weight: 600; 
  min-width: 55px; 
  padding-left: 2px;
  text-align: left;
}