* {
  box-sizing: border-box;
}
body {
  font-family: 'Segoe UI', sans-serif;
  margin: 0;
  background-color: #f5f5f5;
}
/* ==== Navbar ==== */
.navbar {
  background-color: #24292e;
  padding: 12px 0;
}
.navbar .container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  gap: 30px;
  flex-wrap: wrap;
  justify-content: center;
}
.navbar a {
  color: #ffffff;
  text-decoration: none;
  font-size: 16px;
}
.navbar a:hover {
  color: #1abc9c;
}
/* ==== Main Content ==== */
.main-container {
  max-width: 1200px;
  margin: 30px auto;
  background: #fff;
  padding: 30px;
  border-radius: 10px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}
.product-top {
  display: flex;
  gap: 40px;
  flex-wrap: wrap;
}
.product-image {
  flex: 1 1 400px;
  text-align: center;
}
.product-image img {
  max-width: 100%;
  border: 1px solid #ddd;
  border-radius: 6px;
}
.product-info {
  flex: 1 1 600px;
}
.product-info h1 {
  font-size: 26px;
  margin-bottom: 10px;
  color: #222;
}
.product-info .sku {
  font-size: 14px;
  color: #999;
  margin-bottom: 15px;
}
.product-price {
  font-size: 28px;
  color: #e91e63;
  margin: 20px 0;
}
.product-meta {
  font-size: 14px;
  color: #888;
}
.action-buttons {
  margin-top: 25px;
}
.btn {
  display: inline-block;
  background: #e91e63;
  color: #fff;
  padding: 12px 30px;
  font-size: 16px;
  border: none;
  border-radius: 4px;
  margin-right: 15px;
  cursor: pointer;
}
.btn:hover {
  background: #d81b60;
}
.product-detail {
  margin-top: 50px;
}
.product-detail h2 {
  font-size: 22px;
  padding: 10px 0;
  border-bottom: 2px solid #eee;
  color: #333;
}
.product-description {
  font-size: 16px;
  line-height: 1.8;
  color: #444;
  margin-top: 20px;
  white-space: pre-wrap;
}
/* ==== Donation Section ==== */
.donation {
  text-align: center;
  margin: 60px auto 40px;
  padding: 30px 20px;
  background-color: #fefefe;
  border-top: 1px solid #eee;
}
.donation p {
  font-size: 18px;
  color: #4b5563;
  margin-bottom: 1rem;
}
.donation a {
  display: inline-block;
  background-color: #ff69b4;
  color: white;
  padding: 12px 24px;
  font-size: 16px;
  border-radius: 6px;
  text-decoration: none;
  transition: background-color 0.3s ease;
}
.donation a:hover {
  background-color: #e255a0;
}
/* ==== Back Link ==== */
.back-link {
  text-align: center;
  margin: 40px 0 20px;
}
.back-link a {
  color: #007bff;
  text-decoration: none;
  font-weight: bold;
}
.back-link a:hover {
  text-decoration: underline;
}
/* ==== Responsive (Mobile) ==== */
@media (max-width: 768px) {
  .product-top {
    flex-direction: column;
    align-items: center;
  }
  .product-info {
    text-align: center;
  }
  .product-info h1 {
    font-size: 22px;
  }
  .product-price {
    font-size: 24px;
  }
  .btn {
    padding: 12px 20px;
    font-size: 15px;
    margin: 10px 5px;
  }
  .donation p {
    font-size: 16px;
  }
  .donation a {
    width: 90%;
    max-width: 300px;
    font-size: 15px;
  }
  /* 手机端导航横向排列，自动换行，间距与样式优化 */
  .navbar .container {
    flex-direction: row;
    justify-content: center;
    flex-wrap: wrap;
    gap: 12px;
    padding: 10px 10px;
  }
  .navbar a {
    font-size: 15px;
    padding: 8px 12px;
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 4px;
    background-color: rgba(255,255,255,0.05);
    transition: background-color 0.3s ease;
  }
  .navbar a:hover {
    background-color: rgba(255,255,255,0.15);
  }
}