:root {
  --primary: #1a73e8;
  --secondary: #fbbc04;
  --background: #ffffff;
  --text-color: #222;
  --grid-line: rgba(0, 0, 0, 0.1);
  --tooltip-bg: rgba(0, 0, 0, 0.85);
  --tooltip-text: #fff;
  --legend-height: 12px;
  --font-base: system-ui, sans-serif;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --border-radius: 4px;
  --transition-fast: 0.2s ease-in-out;
}

/* ==============================
   Heatmap Grid
   ============================== */
.heatmap-area {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(8px, 1fr));
  gap: 1px;
  background-color: var(--grid-line);
  border: 1px solid var(--grid-line);
  width: 100%;
  height: auto;
  aspect-ratio: 2 / 1;
  position: relative;
}

.heatmap-area div {
  background: var(--secondary);
  transition: background-color var(--transition-fast);
}

.heatmap-area div:hover {
  outline: 1px solid var(--primary);
  cursor: pointer;
}

/* ==============================
   Heatmap Style
   ============================== */
.heatmap-style {
  font-family: var(--font-base);
  color: var(--text-color);
  background: var(--background);
  padding: var(--spacing-md);
}

.heatmap-style .intensity-low {
  background-color: #dceefb;
}

.heatmap-style .intensity-medium {
  background-color: #71c1f0;
}

.heatmap-style .intensity-high {
  background-color: #1a73e8;
}

/* ==============================
   Legend and Tooltip
   ============================== */
.heatmap-legend {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: var(--spacing-md);
  font-size: 0.875rem;
}

.heatmap-legend__scale {
  flex: 1;
  height: var(--legend-height);
  background: linear-gradient(to right, #dceefb, #71c1f0, #1a73e8);
  border-radius: var(--border-radius);
}

.heatmap-legend__labels {
  display: flex;
  justify-content: space-between;
  width: 100%;
  margin-top: var(--spacing-sm);
  font-size: 0.75rem;
}

.tooltip {
  position: absolute;
  background-color: var(--tooltip-bg);
  color: var(--tooltip-text);
  padding: var(--spacing-sm);
  border-radius: var(--border-radius);
  font-size: 0.75rem;
  pointer-events: none;
  opacity: 0;
  transition: opacity var(--transition-fast);
  z-index: 10;
}

.tooltip[aria-hidden="false"] {
  opacity: 1;
}

/* ==============================
   Responsive Adjustments
   ============================== */
@media (min-width: 640px) {
  .heatmap-area {
    grid-template-columns: repeat(auto-fill, minmax(10px, 1fr));
  }
  .heatmap-legend {
    font-size: 1rem;
  }
}

@media (min-width: 1024px) {
  .heatmap-area {
    grid-template-columns: repeat(auto-fill, minmax(12px, 1fr));
  }
}

/* ==============================
   Footer (falls vorhanden)
   ============================== */
footer {
  text-align: center;
  font-size: 0.75rem;
  padding: var(--spacing-md);
  color: var(--text-color);
  border-top: 1px solid var(--grid-line);
}

footer small {
  display: block;
  margin-top: var(--spacing-sm);
  content: "© 2026 Donau2Space.de";
}