body {
  margin: 0;
  padding: 0;
  background: #1e1e2f;
  font-family: 'Segoe UI', sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.calculator {
  width: 100%;
  max-width: 400px;
  background: #1e1e2f;
  border-radius: 20px;
  padding: 20px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
}

.display {
  background: #2c2c5a;
  color: white;
  font-size: 2em;
  padding: 20px;
  border-radius: 15px;
  margin-bottom: 20px;
  text-align: right;
  overflow-x: auto;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 10px;
}

.btn {
  font-size: 1.2em;
  border: none;
  cursor: pointer;
  transition: background 0.2s;
  height: 60px;
}

.btn.number,
.btn.clear,
.btn.equals,
.btn.backspace {
  border-radius: 30px;
  background: #3b3b55;
  color: white;
  font-size: 1.8em;
  display: flex;
  justify-content: center;
  align-items: center;
}

.btn.operator {
  background: orange;
  color: white;
  border-radius: 50%;
  width: 60px;
  height: 60px;
  margin: 0 auto;
  font-size: 1.8em;
  display: flex;
  justify-content: center;
  align-items: center;
  
}

.btn.clear {
  background: red;
}

.btn.equals {
  background: #bfbfbf;
  color: black;
}

.btn.backspace {
  background: #3b3b55;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  position: relative;
}

.backspace-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    display: flex;
}

.backspace-icon svg {
  width: 38px;
  height: 38px;
  fill: white;
}

.history {
  margin-top: 15px;
  font-size: 0.9em;
  color: #ccc;
  max-height: 100px;
  overflow-y: auto;
  padding: 10px;
  border-top: 1px solid #444;
}

.btn:hover {
  opacity: 0.85;
}