body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background: linear-gradient(135deg, #1a1a2e, #16213e, #0f3460);
  background-size: 300% 300%;
  animation: gradientMove 8s infinite;
}

@keyframes gradientMove {
  0% {
    background-position: 0% 50%;
  }
  50% {
    background-position: 100% 50%;
  }
  100% {
    background-position: 0% 50%;
  }
}

.calculator {
  background: #222831;
  border-radius: 16px;
  box-shadow: 0 10px 20px rgba(0, 0, 0, 0.7);
  width: 350px;
  padding: 20px;
}

.calculator .display {
  background: #393e46;
  color: #eeeeee;
  border-radius: 8px;
  padding: 15px;
  text-align: right;
  font-size: 2rem;
  margin-bottom: 20px;
  box-shadow: inset 0 2px 5px rgba(0, 0, 0, 0.3);
}

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

.calculator .button {
  background: #00adb5;
  color: #eeeeee;
  border: none;
  padding: 15px;
  font-size: 1.1rem;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.2s;
}

.calculator .button:hover {
  background: #00969e;
}

.calculator .button.operator {
  background: #393e46;
  color: #00adb5;
}

.calculator .button.operator:hover {
  background: #2c3138;
}

.calculator .button.equals {
  background: #ff5722;
  grid-column: span 4;
}

.calculator .button.equals:hover {
  background: #e64a19;
}

.calculator .button.clear {
  background: #f44336;
}

.calculator .button.clear:hover {
  background: #d32f2f;
}

.calculator .button.advanced {
  background: #4caf50;
}

.calculator .button.advanced:hover {
  background: #388e3c;
}

footer {
  background: #00000000;
  color: #aaa;
  width: 100%;
  text-align: center;
  padding: 1px 0;
  font-size: 0.9rem;
}

footer p {
  margin: 0;
}