* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: "Poppins", sans-serif;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  background: linear-gradient(135deg, #667eea, #764ba2);
}

.calculator {
  width: 320px;
  padding: 20px;
  border-radius: 15px;
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(15px);
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.3);
  display: flex;
  flex-direction: column;
}

.display {
  height: 70px;
  background: rgba(0, 0, 0, 0.7);
  color: #fff;
  font-size: 2rem;
  border-radius: 10px;
  margin-bottom: 15px;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  padding: 0 15px;
  overflow-x: auto;
}

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

.btn {
  height: 60px;
  font-size: 1.2rem;
  font-weight: bold;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn.number {
  background: rgba(255, 255, 255, 0.15);
  color: #fff;
}
.btn.number:hover {
  background: rgba(255, 255, 255, 0.3);
}

.btn.operator {
  background: #ff9f43;
  color: #fff;
}
.btn.operator:hover {
  background: #ff793f;
}

.btn.clear {
  background: #ff4757;
  color: #fff;
}
.btn.clear:hover {
  background: #e84118;
}

.btn.equal {
  background: #2ed573;
  color: #fff;
  grid-row: span 2;
}
.btn.equal:hover {
  background: #1eae60;
}

.btn.zero {
  grid-column: span 2;
}