:root {
  --color-bg: #f8f9fa;
  --color-primary: #3a6ea5;
  --color-accent: #4caf50;
  --color-text: #212529;
  --color-card-bg: #ffffff;
  --color-border: #dee2e6;
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 2rem;
  --font-base: 16px;
  --font-family: system-ui, sans-serif;
  --radius-base: 6px;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 2px 6px rgba(0, 0, 0, 0.1);
  --breakpoint-md: 640px;
  --breakpoint-lg: 1024px;
}

html, body {
  margin: 0;
  padding: 0;
  font-size: var(--font-base);
  font-family: var(--font-family);
  background-color: var(--color-bg);
  color: var(--color-text);
  height: 100%;
}

/* ==============================
   App Layout
   ============================== */

.app-header {
  background-color: var(--color-primary);
  color: #fff;
  padding: var(--spacing-md);
  text-align: center;
  font-weight: 600;
}

.filter-panel {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  padding: var(--spacing-md);
  background-color: var(--color-card-bg);
  border-bottom: 1px solid var(--color-border);
  justify-content: center;
}

.results-chart {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: var(--spacing-lg) var(--spacing-md);
}

.stats-summary {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-md);
  justify-content: center;
  padding: var(--spacing-md);
}

.app-footer {
  text-align: center;
  padding: var(--spacing-sm);
  font-size: 0.875rem;
  color: var(--color-text);
  border-top: 1px solid var(--color-border);
  margin-top: var(--spacing-lg);
}

/* ==============================
   Chart Container
   ============================== */

.chart-container {
  width: 100%;
  max-width: 900px;
  background-color: var(--color-card-bg);
  border-radius: var(--radius-base);
  box-shadow: var(--shadow-md);
  padding: var(--spacing-md);
  margin: auto;
  box-sizing: border-box;
}

.chart-container canvas {
  width: 100%;
  height: auto;
}

/* ==============================
   Summary Cards
   ============================== */

.summary-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: var(--spacing-md);
  width: 100%;
  max-width: 900px;
  margin: auto;
}

.summary-cards .card {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-left: 6px solid var(--color-accent);
  border-radius: var(--radius-base);
  padding: var(--spacing-md);
  box-shadow: var(--shadow-sm);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.summary-cards .card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.summary-cards .card__title {
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
  color: var(--color-primary);
}

.summary-cards .card__value {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-text);
}

/* ==============================
   Responsive Design
   ============================== */

@media (min-width: var(--breakpoint-md)) {
  .filter-panel {
    justify-content: flex-start;
  }
  .results-chart {
    padding: var(--spacing-lg) var(--spacing-lg);
  }
}

@media (min-width: var(--breakpoint-lg)) {
  .summary-cards {
    grid-template-columns: repeat(4, 1fr);
  }
}

/* ==============================
   Footer Copyright
   ============================== */

.app-footer::after {
  display: block;
  content: "© 2026 Donau2Space.de";
  margin-top: var(--spacing-xs);
  font-size: 0.75rem;
  color: var(--color-text);
}