* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: Arial, sans-serif;
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background-color: #f0f0f0;
}

.calculator-container {
  width: 320px;
  background-color: #2c3e50;
  border-radius: 12px;
  padding: 20px;
  box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
}

.calculator-display {
  background-color: #34495e;
  color: #ecf0f1;
  font-size: 2.5rem;
  text-align: right;
  padding: 20px;
  margin-bottom: 20px;
  border-radius: 8px;
  word-wrap: break-word;
  word-break: break-all;
}

.calculator-buttons {
  display: grid;

  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
}

.btn {
  font-size: 1.5rem;
  padding: 20px;
  border: none;
  border-radius: 8px;
  background-color: #7f8c8d;
  color: white;
  cursor: pointer;
  transition: background-color 0.2s ease, transform 0.1s ease;
}

.btn:hover {
  background-color: #95a5a6;
}

.btn:active {
  transform: scale(0.97);
}

.span-2 {
  grid-column: span 2;
}

.btn-operator {
  background-color: #f39c12;
}

.btn-operator:hover {
  background-color: #f1c40f;
}

.btn-equals {
  background-color: #2ecc71;
}

.btn-equals:hover {
  background-color: #27ae60;
}

.btn-clear,
.btn-delete {
  background-color: #e74c3c;
}

.btn-clear:hover,
.btn-delete:hover {
  background-color: #c0392b;
}