body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background: #111;
  color: white;
  font-family: "Segoe UI", sans-serif;
  flex-direction: column;
}

h1{
    color: #9c4dcc;
    align-items: center;
    padding-top: 10px;
    text-align: center;
}

p {
  color: #ccc;
  margin-top: 5px;
  margin-bottom: 20px;
  text-align: center;
  font-size: 1rem;
}

.calculator {
  background: #222;
  border-radius: 20px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.3);
  padding: 20px;
  width: 300px;
}

.display {
  background: #333;
  padding: 20px;
  text-align: right;
  font-size: 2rem;
  border-radius: 10px;
  margin-bottom: 15px;
  overflow-x: auto;
}

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

.btn {
  background: #444;
  border: none;
  padding: 15px;
  font-size: 1.2rem;
  border-radius: 10px;
  cursor: pointer;
  transition: background 0.2s;
}

.btn:hover {
  background: #555;
}
.btn.active {
  background: #777;
  box-shadow: 0 0 10px #aaa;
  transform: scale(0.97);
}
.container {
  display: flex;
  gap: 30px;
  align-items: flex-start;
}

.key-info {
  background: #1b1b1b;
  border-radius: 15px;
  padding: 15px 20px;
  color: #ddd;
  width: 200px;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.3);
}

.key-info h2 {
  margin-top: 0;
  color: #9c4dcc;
  text-align: center;
  font-size: 1.2rem;
}

.key-info ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.key-info li {
  margin-bottom: 8px;
  font-size: 0.95rem;
}

.key-info b {
  color: #fff;
}
.zero {
  grid-column: span 2;
}
/* Responsive Design */
@media (max-width: 700px) {
  .container {
    flex-direction: column;
    align-items: center;
  }

  .key-info {
    width: 90%;
    margin-top: 20px;
  }

  .calculator {
    width: 90%;
  }
}