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

body {
  text-align: center;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  transition: background-color 0.15s ease;
}

h1 {
  color: white;
  font-size: 3.5rem;
  margin-bottom: 0.5rem;
  text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
  letter-spacing: 2px;
  font-weight: 700;
  animation: slideDown 0.6s ease;
}

h2 {
  color: rgba(255, 255, 255, 0.9);
  font-size: 1.3rem;
  margin-bottom: 3rem;
  font-weight: 300;
  letter-spacing: 1px;
  animation: fadeIn 0.8s ease;
}

.btn-container {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 1.5rem;
  margin-bottom: 2rem;
  animation: scaleIn 0.6s ease 0.2s backwards;
}

.line-one, .line-two {
  display: flex;
  gap: 2rem;
  justify-content: center;
}

.btn {
  height: 140px;
  width: 140px;
  border: none;
  border-radius: 15px;
  margin: 0.5rem;
  cursor: pointer;
  font-size: 1.5rem;
  font-weight: bold;
  color: rgba(255, 255, 255, 0.8);
  transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
  position: relative;
  overflow: hidden;
}

.btn:hover {
  transform: translateY(-5px) scale(1.05);
  box-shadow: 0 12px 35px rgba(0, 0, 0, 0.3);
}

.btn:active {
  transform: translateY(-2px) scale(1.02);
}


.yellow {
  background: linear-gradient(135deg, #f99b45 0%, #ff8c42 100%);
}

.red {
  background: linear-gradient(135deg, #d95980 0%, #ff6b6b 100%);
}

.purple {
  background: linear-gradient(135deg, #819ff9 0%, #6c5ce7 100%);
}

.green {
  background: linear-gradient(135deg, #63aac0 0%, #00d2fc 100%);
}


.flash {
  animation: buttonFlash 0.3s ease !important;
}

@keyframes buttonFlash {
  0% {
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
    transform: scale(1);
  }
  50% {
    box-shadow: 0 0 50px rgba(255, 255, 255, 0.8), 
                0 8px 25px rgba(0, 0, 0, 0.2);
    transform: scale(1.08);
  }
  100% {
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
    transform: scale(1);
  }
}

.userflash {
  animation: userClick 0.25s ease !important;
}

@keyframes userClick {
  0% {
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
    filter: brightness(1);
  }
  50% {
    box-shadow: inset 0 0 20px rgba(0, 0, 0, 0.3),
                0 0 30px rgba(255, 255, 255, 0.9);
    filter: brightness(1.3);
  }
  100% {
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
    filter: brightness(1);
  }
}


h2 b {
  color: #ffd700;
  font-size: 1.6rem;
  font-weight: 700;
}


body.game-over {
  background: linear-gradient(135deg, #ff6b6b 0%, #ee5a6f 100%);
  animation: shake 0.3s ease;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-10px); }
  75% { transform: translateX(10px); }
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

@keyframes scaleIn {
  from {
    opacity: 0;
    transform: scale(0.8);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}


@media (max-width: 768px) {
  h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
  }

  h2 {
    font-size: 1.1rem;
    margin-bottom: 2rem;
  }

  .btn {
    height: 110px;
    width: 110px;
    font-size: 1.2rem;
  }

  .line-one, .line-two {
    gap: 1rem;
  }

  .btn-container {
    gap: 1rem;
  }
}

@media (max-width: 480px) {
  h1 {
    font-size: 2rem;
  }

  h2 {
    font-size: 1rem;
  }

  .btn {
    height: 90px;
    width: 90px;
    font-size: 1rem;
  }

  .line-one, .line-two {
    gap: 0.8rem;
  }

  .btn-container {
    gap: 0.8rem;
  }
}