* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Segoe UI", sans-serif;
}

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

.calculator {
  width: 320px;
  padding: 20px;
  border-radius: 20px;
  backdrop-filter: blur(15px);
  background: rgba(255, 255, 255, 0.15);
  box-shadow: 0 25px 45px rgba(0,0,0,0.3);
}

#display {
  width: 100%;
  height: 65px;
  border: none;
  border-radius: 12px;
  margin-bottom: 15px;
  font-size: 26px;
  padding: 10px;
  text-align: right;
  background: rgba(255,255,255,0.25);
  color: #fff;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
}

button {
  height: 55px;
  border: none;
  border-radius: 12px;
  font-size: 18px;
  color: #fff;
  background: rgba(255,255,255,0.2);
  cursor: pointer;
  transition: 0.2s ease;
}

button:hover {
  background: rgba(255,255,255,0.35);
  transform: scale(1.05);
}

.operator {
  background: #4f46e5;
}

.clear {
  background: #dc2626;
}

.equal {
  grid-column: span 2;
  background: #16a34a;
}