/* ========== 基础重置 & 全局样式 ========== */
:root {
  --primary-color: #333;
  --secondary-color: #666;
  --light-color: #f9f9f9;
  --white-color: #fff;
  --black-color: #1a1a1a;
  --shadow-sm: 0 1px 5px rgba(0,0,0,0.02);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.06);
  --shadow-lg: 0 20px 40px rgba(0,0,0,0.15);
  --transition-base: all 0.3s ease;
  --transition-slow: all 0.6s cubic-bezier(0.25, 0.8, 0.25, 1);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  -webkit-tap-highlight-color: transparent;
  outline: none;
}

ul, li {
  list-style: none;
}

a {
  text-decoration: none;
  color: inherit;
}

img {
  display: block;
  max-width: 100%;
  height: auto;
}

body {
  font-family: "Microsoft Yahei", "PingFang SC", sans-serif;
  color: var(--primary-color);
  background-color: var(--white-color);
  overflow-x: hidden;
  font-size: 16px;
  line-height: 1.6;
  scroll-behavior: smooth;
}

/* ========== 标题通用样式 ========== */
.section-sub {
  font-size: clamp(0.8rem, 1.5vw, 1rem);
  margin-bottom: clamp(0.5rem, 1vw, 1rem);
  margin-top: 0 !important;
  text-transform: uppercase;
  color: #999;
  letter-spacing: 2px;
}

.sec-title {
  font-size: clamp(1.4rem, 3vw, 2rem);
  margin-bottom: clamp(1.5rem, 3vw, 3rem);
  color: var(--primary-color);
  margin-top: 0.5rem !important;
}

/* ========== 布局通用样式 ========== */
.section {
  padding: 80px 1rem 2rem !important;
  max-width: 1200px;
  margin: 0 auto;
}

/* ========== 无障碍优化 ========== */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.001s !important;
    transition-duration: 0.001s !important;
  }
}

/* ========== 骨架屏加载样式 ========== */
.skeleton {
  background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
  background-size: 200% 100%;
  animation: skeleton-loading 1.5s infinite;
}
@keyframes skeleton-loading {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

/* ========== 全局动画基础 ========== */
.fade-in {
  animation: fadeIn 0.8s ease forwards;
  opacity: 0;
}
@keyframes fadeIn {
  to { opacity: 1; }
}

.fade-up {
  animation: fadeUp 0.8s ease forwards;
  opacity: 0;
  transform: translateY(30px);
}
@keyframes fadeUp {
  to { opacity: 1; transform: translateY(0); }
}