:root {
  --bg: #1b1b1b;
  --panel-bg: #232323;
  --accent: #799b3e;
  --accent-light: #9bc25a;
  --text: #e6e6e6;
  --border: #3a3a3a;
  --danger: #c0392b;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Segoe UI", Arial, sans-serif;
}

.app-header {
  padding: 12px 20px;
  border-bottom: 1px solid var(--border);
}

.app-header h1 {
  margin: 0;
  font-size: 18px;
  font-weight: 600;
  color: var(--accent-light);
}

.app-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  grid-template-rows: auto auto auto;
  gap: 16px;
  padding: 16px 20px;
}

.panel {
  background: var(--panel-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px;
}

.panel h2 {
  margin: 0 0 8px 0;
  font-size: 14px;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.panel-controls {
  grid-column: 1 / span 2;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.panel-top-controls {
  grid-column: 1 / span 2;
  display: flex;
  flex-direction: row;
  gap: 16px;
  flex-wrap: wrap;
  background: none;
  border: none;
  padding: 0;
}

.panel-top-controls .control-group {
  flex: 1 1 260px;
  background: var(--panel-bg);
}

.canvas-wrap {
  position: relative;
  display: inline-block;
}

canvas {
  max-width: 100%;
  height: auto;
  background: #111;
  border-radius: 4px;
  display: block;
}

#frameCanvas {
  cursor: crosshair;
  touch-action: none; /* let JS handle drags instead of the browser scrolling/zooming */
}

#spectrumCanvas {
  cursor: crosshair;
  touch-action: none; /* dragging on the plot inspects values instead of scrolling the page */
}

.roi-legend {
  margin-top: 8px;
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  font-size: 12px;
  color: #bdbdbd;
}

.legend-item {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.legend-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  display: inline-block;
}

.legend-dot-vertical {
  background: #f2d024;
}

.legend-dot-horizontal {
  background: #4fc3f7;
}

.frame-hint {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: #888;
  font-size: 13px;
  text-align: center;
  pointer-events: none;
  width: 80%;
}

.chart-actions {
  margin-top: 8px;
  display: flex;
  justify-content: flex-end;
}

.control-row {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.control-row label {
  font-size: 13px;
  color: #bdbdbd;
}

button, select, input[type="number"] {
  background: #2c2c2c;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 6px 12px;
  font-size: 13px;
}

input[type="number"] {
  width: 80px;
}

button {
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s;
}

button:hover:not(:disabled) {
  background: var(--accent);
  border-color: var(--accent);
  color: #111;
}

button:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.control-group {
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 10px 12px 12px;
  margin: 0;
}

.control-group legend {
  padding: 0 6px;
  font-size: 12px;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.status-row {
  justify-content: flex-end;
}

.status-msg {
  font-size: 12px;
  color: var(--accent-light);
  margin-left: auto;
}

@media (max-width: 900px) {
  .app-grid {
    grid-template-columns: 1fr;
  }
  .panel-controls,
  .panel-top-controls {
    grid-column: 1;
  }
  .panel-top-controls {
    flex-direction: column;
  }
  .panel-top-controls .control-group {
    /* the 260px flex-basis above is meant as a min-width for the row
       layout on desktop; in column mode it would otherwise be read as a
       min-height, stretching each box with empty space */
    flex: none;
  }
}