* {
  box-sizing: border-box;
}

body {
  font-family: "Microsoft JhengHei", sans-serif;
  max-width: 800px;
  margin: 0 auto;
  padding: 1rem;
}

header {
  position: relative;
}

header h1 {
  text-align: center;
  color: #333;
}

#authArea {
  position: absolute;
  top: 0;
  right: 0;
}

#authArea .user-email {
  color: #666;
  font-size: 0.9rem;
  margin-right: 0.5rem;
}

#authArea .logout-btn {
  padding: 0.3rem 0.6rem;
  background: #888;
  color: white;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  font-size: 0.85rem;
}

#authArea .logout-btn:hover {
  background: #555;
}

.login-msg {
  margin-top: 0.5rem;
  font-size: 0.9rem;
}

.login-msg.success {
  color: #27ae60;
}

.login-msg.error {
  color: #c0392b;
}

#mainContent {
  display: none;
}

#mainContent.visible {
  display: block;
}

#loginSection {
  display: none;
}

#loginSection.visible {
  display: block;
}

.form-section,
.list-section {
  background: #f9f9f9;
  padding: 1.5rem;
  margin: 1rem 0;
  border-radius: 8px;
}

h2 {
  margin-top: 0;
  color: #555;
}

form label {
  display: block;
  margin: 0.5rem 0;
}

form input {
  margin-left: 0.5rem;
  padding: 0.4rem;
}

form button {
  margin-top: 0.5rem;
  padding: 0.5rem 1rem;
  background: #4a90d9;
  color: white;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}

form button:hover {
  background: #357abd;
}

#productList {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.product-card {
  background: white;
  padding: 1rem;
  border-radius: 6px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
  min-width: 180px;
}

.product-card .name {
  font-weight: bold;
  margin-bottom: 0.3rem;
}

.product-card .price,
.product-card .quantity {
  color: #666;
  font-size: 0.9rem;
}

.product-card button {
  margin-top: 0.5rem;
  padding: 0.3rem 0.6rem;
  font-size: 0.85rem;
  background: #e74c3c;
  color: white;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}

.product-card button:hover {
  background: #c0392b;
}

.loading {
  color: #888;
}

.error {
  color: #c0392b;
}