body {
  justify-content: center;
  align-items: center;
  height: 100vh;
  background-color: #f8f8f8;
}

.calculator {
  width: 500px;
  margin: 0 auto;
  background-color: white;
  padding: 20px;
  border-radius: 10px;
  box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.1);
  text-align: center;
  margin-top: 50px;
}

.header {
  background-color: #d9534f;
  color: white;
  font-size: 18px;
  font-weight: bold;
  padding: 10px;
  border-radius: 5px 5px 0 0;
}

#display {
  width: 100%;
  height: 50px;
  font-size: 24px;
  text-align: right;
  border: none;
  outline: none;
  padding: 5px;
  margin-bottom: 10px;
  border-radius: 5px;
  background: #eee;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 5px;
}

button {
  padding: 10px;
  font-size: 16px;
  border: none;
  background: #f2dede;
  border-radius: 5px;
  cursor: pointer;
}

button:hover {
  background: #e6c3c3;
}

button.active {
  background: #d9534f;
  color: white;
}

.about {
  width: 900px;
  background: #fef6e4;
  padding: 20px;
  border-radius: 8px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
  border: 2px solid white;
  float: left;
  margin-top: 2%;
  margin-left: 20%;
  margin-right: 5%;
}
.about-h {
  text-align: center;
  margin-top: 3%;
  margin-bottom: 3%;
  clear: both;
}

/* Responsive Design */
@media (max-width: 768px) {
  .buttons {
    grid-template-columns: repeat(3, 1fr); /* 3 buttons per row */
  }

  .calculator {
    width: 90%;
    padding: 15px;
    margin-left: 4%;
  }

  .about {
    width: 90%;
    padding: 15px;
    margin-left: 4%;
  }
}

@media (max-width: 480px) {
  .buttons {
    grid-template-columns: repeat(2, 1fr); /* 2 buttons per row */
  }

  .calculator {
    padding: 10px;
  }

  button {
    font-size: 14px;
    padding: 8px;
  }
}