/* Base Reset and Typography */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
}

body {
  background-color: #f4f6f8;
  color: #333;
  display: flex;
  justify-content: center;
  padding: 40px 20px;
}

.app-container {
  max-width: 800px;
  width: 100%;
  background: #ffffff;
  padding: 30px;
  border-radius: 12px;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
}

.app-header {
  text-align: center;
  margin-bottom: 25px;
}

.app-header h1 {
  color: #2c3e50;
  margin-bottom: 8px;
}

.app-header p {
  color: #666;
}

/* Status Bar */
.status-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
  font-weight: bold;
  font-size: 1.1rem;
}

.btn {
  background-color: #3498db;
  color: white;
  border: none;
  padding: 8px 16px;
  border-radius: 6px;
  cursor: pointer;
  transition: background 0.2s;
}

.btn:hover {
  background-color: #2980b9;
}

/* Feedback Box */
.feedback-message {
  text-align: center;
  font-weight: bold;
  min-height: 24px;
  margin-bottom: 15px;
}

/* Matching Grid Layout */
.matching-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

.column h2 {
  font-size: 1.1rem;
  color: #7f8c8d;
  margin-bottom: 15px;
  text-align: center;
}

/* Card Styling */
.card {
  background: #fdfdfd;
  border: 2px solid #e2e8f0;
  padding: 15px;
  border-radius: 8px;
  margin-bottom: 12px;
  cursor: pointer;
  text-align: center;
  transition: all 0.2s ease;
  user-select: none;
}

.card:hover {
  border-color: #3498db;
  transform: translateY(-2px);
}

/* Interactivity States */
.card.selected {
  border-color: #3498db;
  background-color: #ebf5fb;
  box-shadow: 0 0 8px rgba(52, 152, 219, 0.3);
}

.card.matched {
  background-color: #e8f8f5;
  border-color: #2ecc71;
  color: #27ae60;
  cursor: default;
  opacity: 0.7;
}

.card.matched:hover {
  transform: none;
}

/* Mobile Responsiveness */
@media (max-width: 600px) {
  .matching-grid {
    grid-template-columns: 1fr;
  }
}