/* ============================================
   公共颜色变量
   ============================================ */
:root {
  --color-primary: #2B5797;
  --color-primary-text: #FFFFFF;
}

/* ============================================
   全局重置 & 基础字体
   ============================================ */
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei",
               "Helvetica Neue", Arial, sans-serif;
  color: #333;
  line-height: 1.6;
  background: #fff;
}
a { text-decoration: none; color: inherit; }
ul { list-style: none; }

/* ============================================
   导航栏 (Header)
   ============================================ */
.site-header {
  background: #fff;
  border-bottom: 1px solid #eee;
  transition: box-shadow 0.3s ease, background-color 0.3s ease;
}
/* 滚动/聚焦时可加阴影（静态站预留） */
.site-header:hover {
  box-shadow: 0 2px 12px rgba(43, 87, 151, 0.06);
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 18px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

/* ---------- 品牌区 Hover ---------- */
.brand {
  transition: transform 0.3s ease;
  cursor: pointer;
}
.brand:hover {
  transform: translateY(-1px);
}
.brand .brand-name {
  font-size: 22px;
  font-weight: 700;
  color: var(--color-primary);
  letter-spacing: 0.5px;
  transition: color 0.3s ease, letter-spacing 0.3s ease;
}
.brand:hover .brand-name {
  letter-spacing: 1px;
}
.brand .brand-slogan {
  font-size: 14px;
  color: #666;
  margin-top: 2px;
  transition: color 0.3s ease;
}
.brand:hover .brand-slogan {
  color: #888;
}

/* ---------- 导航链接 Hover ---------- */
.nav-links {
  display: flex;
  gap: 42px;
}
.nav-links a {
  font-size: 17px;
  font-weight: 500;
  color: #444;
  position: relative;
  padding: 4px 2px;
  cursor: pointer;
  /* 基础过渡 */
  transition: color 0.3s ease,
              transform 0.25s ease,
              background-color 0.3s ease;
}
/* 下划线 —— 默认隐藏 */
.nav-links a::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 50%;
  width: 0;
  height: 2px;
  background: var(--color-primary);
  transition: width 0.35s cubic-bezier(0.4, 0, 0.2, 1),
              left 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}
/* Hover 态：颜色 + 下划线从中心展开 + 轻微上移 */
.nav-links a:hover {
  color: var(--color-primary);
  transform: translateY(-2px);
}
.nav-links a:hover::after {
  width: 100%;
  left: 0;
}
/* Active 态（当前页） */
.nav-links a.active {
  color: var(--color-primary);
}
.nav-links a.active::after {
  width: 100%;
  left: 0;
}

/* ============================================
   页脚 (Footer)
   ============================================ */
.site-footer {
  background: #1a1a1a;
  padding: 36px 24px;
  text-align: center;
  color: #aaa;
  font-size: 14px;
  line-height: 1.9;
  position: relative;
  overflow: hidden;
}
/* 页脚顶部渐变装饰线 */
.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg,
    transparent 0%,
    var(--color-primary) 20%,
    #4a7bc7 50%,
    var(--color-primary) 80%,
    transparent 100%);
  background-size: 200% 100%;
  animation: footerGlow 8s linear infinite;
}
@keyframes footerGlow {
  0%   { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

.site-footer .copyright {
  color: #ccc;
  margin-bottom: 4px;
  display: inline-block;
  transition: color 0.3s ease, transform 0.3s ease;
  cursor: default;
}
.site-footer:hover .copyright {
  color: #fff;
  transform: translateY(-1px);
}

.site-footer .icp {
  color: #888;
  font-size: 13px;
  transition: color 0.3s ease, letter-spacing 0.3s ease;
}
.site-footer:hover .icp {
  color: #aaa;
  letter-spacing: 1px;
}
.site-footer .icp .icp-icon {
  margin-right: 4px;
  display: inline-block;
  width: 12px;
  height: 12px;
}

/* ============================================
   公共响应式（导航相关）
   ============================================ */
@media (max-width: 768px) {
  .nav-container { flex-direction: column; gap: 12px; }
  .nav-links { gap: 20px; }
  /* 移动端减少 hover 位移，避免拥挤 */
  .nav-links a:hover { transform: none; }
}