body {
  font-family: Arial, sans-serif;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  height: 100vh;
  color: white;
  background-color: #1b1b1b;
  margin: 0;
}

.calculator-container {
  width: 280px;
  background-color: #e6f9ff;
  padding: 20px;
  border-radius: 10px;
  border: #4a6ea9 solid 6px;
}

.display {
  display: flex;
  width: 95%;
  flex-direction: column;
  justify-content: center;
  height: 60px;
  margin: 0px 10px 10px 0px;
  font-size: 24px;
  padding: 0px 10px;
  text-align: right;
  border: 1px solid #ccc;
  border-radius: 5px;
  color: black;
  background-color: #f4f4f4;
  box-shadow: 1px 1px 2px rgba(0, 0, 0, 0.7);
}

#history {
  margin: 0px;
  padding: 0px;
  font-size: 14px;
  color: rgb(88, 88, 88);
}

#expression {
  margin: 0px;
  padding: 0px;
}

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

button {
  width: 100%;
  height: 60px;
  font-size: 18px;
  padding: 20px;
  margin-bottom: 10px;
  color: white;
  background-color: #4a6ea9;
  border: none;
  border-radius: 5px;
  box-shadow: 2px 2px 3px rgba(0, 0, 0, 0.7);
  cursor: pointer;
  transition: background-color 0.3s ease;
}

button:hover {
  background-color: #3a5d8e;
}

button:active {
  background-color: #2e4c73;
}