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

body {
  font-family: 'Trebuchet MS', sans-serif;
  background-color: #f1f1f1;
}

.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: 250px;
  height: 100vh;
  background-color: #333;
  color: #fff;
  padding: 20px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start;
}

.sidebar h2 {
  font-size: 24px;
  margin-bottom: 20px;
}

.difficulty {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start;
  margin-bottom: 20px;
}

.difficulty-btn {
  background-color: #fff;
  color: #333;
  border: none;
  padding: 10px 20px;
  border-radius: 5px;
  margin-bottom: 10px;
  cursor: pointer;
  font-weight: bold;
  transition: background-color 0.3s ease-in-out, color 0.3s ease-in-out;
}

.difficulty-btn:hover {
  background-color: #333;
  color: #fff;
}

.sidebar-hidden {
  transform: translateX(-100%);
}

.game-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100vh;
}

.select {
  font-size: 120px;
  margin-bottom: 20px;
}

.points, .time {
  font-size: 24px;
  margin-bottom: 20px;
}

.popup {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background-color: rgba(0, 0, 0, 0.8);
  color: #fff;
  padding: 20px;
  border-radius: 5px;
  z-index: 9999;
  opacity: 0;
  transition: opacity 0.3s ease-in-out;
}

.popup.show {
  opacity: 1;
}

.popup-content {
  text-align: center;
}

.popup-text {
  margin: 0;
  font-size: 24px;
}

.popup-replay {
  display: inline-block;
  background-color: #fff;
  color: #333;
  border: none;
  padding: 10px 20px;
  border-radius: 5px;
  margin-top: 20px;
  cursor: pointer;
  font-weight: bold;
  text-decoration: none;
  transition: background-color 0.3s ease-in-out, color 0.3s ease-in-out;
}

.popup-replay:hover {
  background-color: #333;
  color: #fff;
}