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


body {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #6a0dad, #2c003e);
  color: #fff;
}


.calc-wrap {
  width: 100%;
  max-width: 360px;
  padding: 20px;
}


.calculator {
  background: #1e1e2f;
  padding: 20px;
  border-radius: 14px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
}


#display {
  width: 100%;
  height: 60px;
  font-size: 1.5rem;
  margin-bottom: 14px;
  border-radius: 10px;
  padding: 10px;
  text-align: center;
  background: #2a2a40;
  border: 2px solid #6a0dad;
  color: #fff;
  box-sizing: border-box;
}


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


button {
  padding: 14px;
  font-size: 1.1rem;
  border-radius: 8px;
  border: 2px solid #2a2a40;
  background: #3d3d5c;
  color: #fff;
  cursor: pointer;
  transition: 0.15s;
}

button:hover {
  transform: translateY(-3px);
  background: #6a0dad;
}


.equals {
  grid-row: span 2;
  background: #6a0dad;
  border-color: #6a0dad;
}

.zero {
  grid-column: span 2;
}