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

#calculator {
  width: 100%;
  height: 100%;
  max-width: 800px;
  max-height: 800px;
  margin: auto;
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  background-color: #ffffff;
}

#display {
  width: 100%;
  height: 40px;
  margin-bottom: 10px;
  text-align: right;
  padding: 5px;
  font-size: 18px;
  border: 1px solid #ccc;
  border-radius: 3px;
  box-shadow: inset 0 0 5px rgba(0, 0, 0, 0.1);
}

#buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 5px;
  width: 100%;
}

button {
  padding: 2vh;
  font-size: 2vh;
  border: none;
  border-radius: 3px;
  background-color: #e0e0e0;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
  cursor: pointer;
  transition: background-color 0.3s ease;
}

button:hover {
  background-color: #d5d5d5;
}

button:active {
  background-color: #ccc;
  box-shadow: inset 0 2px 5px rgba(0, 0, 0, 0.2);
}

.calculator-content {
  max-width: 800px;
  width: 100%;
  padding: 16px;
  background: #2d3748;
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-height: 600px;
}

.calculator-display {
  background: #000000;
  color: #00ff00;
  padding: 12px;
  text-align: right;
  font-family: 'Courier New', monospace;
  font-size: 18px;
  border: 1px solid #4a5568;
  border-radius: 4px;
  min-height: 40px;
  display: flex;
  align-items: center;
  justify-content: flex-end;
}

.calculator-buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
}

.calculator-button {
  height: 40px;
  background: #4a5568;
  border: 1px solid #2d3748;
  color: #e2e8f0;
  border-radius: 4px;
  cursor: pointer;
  font-size: 14px;
  font-weight: bold;
  transition: all 0.2s ease;
}

.calculator-button:hover {
  background: #2b6cb0;
}

.calculator-button:active {
  transform: scale(0.95);
}

.calculator-button.operator {
  background: #3182ce;
}

.calculator-button.equals {
  background: #10b981;
}