body {
  font-family: 'Helvetica Neue', sans-serif;
  background: #f5f8fa;
  padding: 30px;
}

.invoice-container {
  background: #fff;
  max-width: 800px;
  margin: auto;
  padding: 30px;
  border-radius: 10px;
  box-shadow: 0 0 15px rgba(0,0,0,0.08);
}

input {
  width: 100%;
  padding: 10px;
  margin: 10px 0;
  border-radius: 6px;
  border: 1px solid #ccc;
}

.item-row {
  display: flex;
  gap: 10px;
}

.item-row input {
  flex: 1;
}

button {
  padding: 10px 20px;
  background: #007bff;
  color: #fff;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  margin-top: 15px;
}

.output {
  margin-top: 30px;
  background: #eef4fc;
  padding: 20px;
  border-left: 5px solid #007bff;
  white-space: pre-wrap;
  font-family: monospace;
}