* {
  box-sizing: border-box;
}
html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  font-family: Inter, system-ui, Arial, sans-serif;
  background: linear-gradient(135deg, #ffe9b3, #ec8a11);

  display: flex;
  align-items: center;
  justify-content: center;
}

#calculator {
  background: white;
  padding: 20px;
  border-radius: 14px;
  box-shadow: 0 8px 25px rgba(0,0,0,0.08);
  width: 320px;
}

#display {
  background: linear-gradient(180deg, #fff7f0, #fffdfa);
  padding: 15px;
  font-size: 1.5rem;
  border-radius: 8px;
  text-align: right;
  margin-bottom: 15px;
  border: 1px solid rgba(0,0,0,0.05);
  color: #5a3b00;
}

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

button {
  padding: 15px;
  font-size: 1.2rem;
  border: none;
  border-radius: 10px;
  background: linear-gradient(180deg, #fff, #f8f8f8);
  box-shadow: 0 4px 8px rgba(0,0,0,0.05);
  cursor: pointer;
  transition: all 0.08s ease-in-out;
}

button:active {
  transform: translateY(2px);
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

button.operator {
  background: #ffecd1;
  color: #8b4513;
  font-weight: bold;
}

button.equal {
  background: #fcd34d;
  font-weight: bold;
}

button.clear {
  background: #f87171;
  color: white;
  font-weight: bold;
}