@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;600&display=swap');

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Inter', sans-serif;
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background: linear-gradient(135deg, #dbe6f6, #c8c7ff);
}

.calculator {
  background: rgba(255, 255, 255, 0.15);
  backdrop-filter: blur(20px);
  border-radius: 25px;
  padding: 25px;
  box-shadow: 0 20px 40px rgba(0,0,0,0.2), 0 0 50px rgba(255,255,255,0.1);
  width: 320px;
}

#display {
  width: 100%;
  height: 60px;
  font-size: 1.8rem;
  text-align: right;
  margin-bottom: 20px;
  border-radius: 15px;
  border: none;
  padding: 0 15px;
  background: rgba(255,255,255,0.25);
  box-shadow: inset 0 4px 8px rgba(0,0,0,0.1);
  color: #333;
}

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

button {
  padding: 22px;
  font-size: 1.3rem;
  border-radius: 15px;
  border: none;
  cursor: pointer;
  background: linear-gradient(135deg, #6a11cb, #2575fc);
  color: white;
  transition: transform 0.15s ease, background 0.3s ease, box-shadow 0.3s ease;
  box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

button:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(0,0,0,0.2);
  background: linear-gradient(135deg, #2575fc, #6a11cb);
}

button:active {
  transform: translateY(1px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

button.equal {
  background: linear-gradient(135deg, #ff512f, #dd2476);
  grid-row: span 2;
}

button.equal:hover {
  background: linear-gradient(135deg, #dd2476, #ff512f);
}

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

button:focus {
  outline: none;
}

/* Responsive adjustments */
@media (max-width: 360px) {
  .calculator {
    width: 90%;
    padding: 20px;
  }

  #display {
    font-size: 1.5rem;
    height: 50px;
  }

  button {
    padding: 18px;
    font-size: 1.1rem;
  }
}