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

body {
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #2c3e50, #8e44ad);
  background-size: cover;
  color: white;
  user-select: none;
  overflow: hidden;
}

.calculator {
  background: rgba(13, 71, 161, 0.8);
  border-radius: 20px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
  overflow: hidden;
  width: 90%;
  max-width: 320px;
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.1);
  margin: 20px;
}

.display {
  background: linear-gradient(145deg, #1e1e1e, #2a2a2a);
  color: #00ff00;
  font-size: 36px;
  font-family: 'Digital-7', monospace;
  padding: 20px;
  text-align: right;
  border: 2px solid rgba(255, 255, 255, 0.1);
  border-radius: 10px;
  margin: 20px;
  box-shadow: inset 0 4px 8px rgba(0, 0, 0, 0.5), inset 0 -4px 8px rgba(255, 255, 255, 0.1);
  overflow: hidden;
  white-space: nowrap;
  position: relative;
}

.display input {
  background: transparent;
  border: none;
  color: #00ff00;
  font-size: 36px;
  font-family: 'Digital-7', monospace;
  width: 100%;
  text-align: right;
  outline: none;
  caret-color: #00ff00;
  animation: slideIn 0.3s ease-in-out;
}

@keyframes slideIn {
  0% {
      transform: translateX(10px);
      opacity: 0.5;
  }
  100% {
      transform: translateX(0);
      opacity: 1;
  }
}

.animate {
  display: inline-block;
  animation: slideIn 0.3s ease-in-out;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-gap: 10px;
  padding: 20px;
}

.button {
  background: linear-gradient(145deg, #4a4a4a, #3a3a3a);
  color: #fff;
  font-size: 24px;
  font-family: 'Arial', sans-serif;
  border: none;
  border-radius: 10px;
  padding: 15px;
  cursor: pointer;
  transition: all 0.3s ease;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3), inset 0 -2px 4px rgba(255, 255, 255, 0.1);
  position: relative;
  overflow: hidden;
}

.button::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(145deg, rgba(255, 255, 255, 0.1), rgba(255, 255, 255, 0));
  border-radius: 10px;
  z-index: 1;
}

.button:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.4), inset 0 -2px 4px rgba(255, 255, 255, 0.1);
}

.button:active {
  transform: translateY(0);
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.3), inset 0 2px 4px rgba(0, 0, 0, 0.2);
}

.button:focus {
  outline: none;
}

.button[onclick="calculateResult()"] {
  background: linear-gradient(145deg, #ff6f61, #ff3b3f);
  grid-column: span 2;
}

.button[onclick="calculateResult()"]:hover {
  background: linear-gradient(145deg, #ff3b3f, #ff6f61);
}

.button[onclick="clearDisplay()"],
.button[onclick="backspace()"] {
  background: linear-gradient(145deg, #6c5ce7, #a29bfe);
}

.button[onclick="clearDisplay()"]:hover,
.button[onclick="backspace()"]:hover {
  background: linear-gradient(145deg, #a29bfe, #6c5ce7);
}

.button.zero {
  grid-column: span 2;
  background: linear-gradient(145deg, #5ce763, #82c714);
}

.button:nth-child(3),
.button:nth-child(4),
.button:nth-child(8),
.button:nth-child(12),
.button:nth-child(16) {
  background: linear-gradient(45deg, yellow, orange);
  color: black;
  font-weight: bold;
  border: none;
  box-shadow: 2px 2px 5px rgba(0, 0, 0, 0.2);
  transition: all 0.3s ease;
}

.button:nth-child(3):hover,
.button:nth-child(4):hover,
.button:nth-child(8):hover,
.button:nth-child(12):hover,
.button:nth-child(16):hover {
  background: linear-gradient(45deg, orange, yellow);
  transform: scale(1.1);
}

@media (max-width: 480px) {
  .calculator {
    width: 100%;
    border-radius: 0;
    margin: 0;
  }

  .display {
    font-size: 28px;
    padding: 15px;
    margin: 10px;
  }

  .buttons {
    grid-gap: 5px;
    padding: 10px;
  }

  .button {
    font-size: 20px;
    padding: 10px;
  }
}