body {
  font-family: sans-serif;
  margin: 0;
  padding: 0;
  background: #f7f7f7;
}
header {
  background: #4a90e2;
  color: #fff;
  padding: 16px;
  text-align: center;
  font-size: 20px;
}
.container {
  padding: 16px;
  max-width: 480px;
  margin: auto;
}
.card {
  background: #fff;
  padding: 16px;
  margin-bottom: 12px;
  border-radius: 10px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.08);
}
input, button {
  width: 100%;
  padding: 12px;
  margin-top: 8px;
  font-size: 16px;
  border-radius: 8px;
  border: 1px solid #ccc;
  box-sizing: border-box;
}
button {
  background: #4a90e2;
  color: #fff;
  border: none;
  margin-top: 12px;
}
.expense-item {
  display: flex;
  flex-direction: column;
  margin-bottom: 8px;
  font-size: 16px;
}
.payer-select {
  display: flex;
  gap: 12px;
  margin-top: 8px;
}
.result-box {
  font-size: 18px;
  font-weight: bold;
  color: #333;
}