/* Overall layout */
body {
  background: #f3f6fa;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  font-family: Arial, sans-serif;
}

/* Calculator box */
.calculator {
  background-color: #2196f3;
  border-radius: 25px;
  box-shadow: 0px 6px 15px rgba(0, 0, 0, 0.3);
  padding: 20px;
  width: 260px;
}

/* Display screen */
.display {
  background-color: #e3f2fd;
  border-radius: 10px;
  margin-bottom: 15px;
  padding: 10px;
  text-align: right;
}

.display input {
  width: 100%;
  border: none;
  background: transparent;
  font-size: 2em;
  color: black;
  text-align: right;
  outline: none;
}

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

/* Basic button style */
button {
  background-color: #1976d2;
  color: white;
  border: none;
  font-size: 1.3em;
  border-radius: 10px;
  height: 60px;
  cursor: pointer;
  transition: 0.2s;
}

/* Hover effect */
button:hover {
  background-color: #1565c0;
}

/* Operator buttons (+ - * /) */
button.operator {
  background-color: #0d47a1;
}

/* Clear button */
button.clear {
  background-color: #e53935;
}

button.clear:hover {
  background-color: #c62828;
}

/* Equal button */
button.equal {
  background-color: #43a047;
}

button.equal:hover {
  background-color: #2e7d32;
}

/* Press effect */
button:active {
  transform: scale(0.95);
}