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

body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background: linear-gradient(135deg, #74ebd5, #9face6);
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

.calculator {
  background: rgba(255, 255, 255, 0.15);
  backdrop-filter: blur(12px);
  border-radius: 20px;
  padding: 25px 20px;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
  width: 320px;
}

.screen {
  background: rgba(255, 255, 255, 0.85);
  border-radius: 10px;
  padding: 15px;
  margin-bottom: 20px;
  min-height: 70px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  box-shadow: inset 0 0 5px rgba(0, 0, 0, 0.1);
}

#expression {
  font-size: 18px;
  color: #444;
  text-align: right;
  word-wrap: break-word;
}

#result {
  font-size: 28px;
  font-weight: bold;
  color: #000;
  text-align: right;
  margin-top: 5px;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 15px;
}

button {
  height: 60px;
  font-size: 22px;
  border: none;
  border-radius: 12px;
  cursor: pointer;
  transition: 0.2s ease;
  background-color: #ffffff40;
  color: #222;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
}

button:hover {
  background-color: #ffffff60;
  transform: translateY(-2px);
}

button:active {
  transform: scale(0.97);
}

.operator {
  background-color: #fcbf49;
  color: white;
}

.clear {
  background-color: #ff6b6b;
  color: white;
}

.equal {
  background-color: #4caf50;
  color: white;
  grid-column: span 2;
}