/* Reset */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* Background */
body {
  font-family: 'Segoe UI', sans-serif;
  background: linear-gradient(135deg, #1abc9c, #16a085, #2ecc71);
  background-size: 400% 400%;
  animation: gradientBG 12s ease infinite;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

/* Container */
.game-container {
  width: 90%;
  max-width: 900px;
  background: #ffffffee;
  border-radius: 20px;
  padding: 30px;
  box-shadow: 0px 8px 25px rgba(0, 0, 0, 0.25);
  text-align: center;
}

/* Header */
header h1 {
  color: #2c3e50;
  margin-bottom: 15px;
}

.progress-bar {
  width: 100%;
  height: 15px;
  background: #dfe6e9;
  border-radius: 10px;
  overflow: hidden;
  margin-bottom: 20px;
}

#progress {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, #3498db, #9b59b6);
  transition: width 0.5s ease-in-out;
}

/* Flashcard */
.flashcard {
  font-size: 70px;
  font-weight: bold;
  padding: 80px 20px;
  background: #3498db;
  color: white;
  border-radius: 20px;
  margin: 20px 0;
  cursor: pointer;
  box-shadow: 0px 5px 15px rgba(0,0,0,0.2);
  transition: transform 0.3s, background 0.3s;
}

.flashcard:hover {
  background: #2ecc71;
  transform: scale(1.05);
}

/* Controls */
.controls {
  margin: 20px 0;
}

.controls button {
  background: #9b59b6;
  color: white;
  font-size: 18px;
  padding: 12px 30px;
  margin: 10px;
  border: none;
  border-radius: 12px;
  cursor: pointer;
  transition: 0.3s;
}

.controls button:hover {
  background: #8e44ad;
}

/* Footer */
footer p {
  font-size: 18px;
  color: #2c3e50;
  font-weight: bold;
}

/* Background Animation */
@keyframes gradientBG {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}