/* ========== 精准传媒 SEO 头部 - 白底专业风 ========== */
:root {
  --seo-bg: #ffffff;
  --seo-surface: #f4f6f9;
  --seo-primary: #1a5fdc;          /* 专业蓝 */
  --seo-primary-dark: #1349b0;
  --seo-accent: #f0b90b;          /* 金色点缀 */
  --seo-text: #1e293b;
  --seo-text-soft: #64748b;
  --seo-text-light: #94a3b8;
  --seo-border: #e2e8f0;
  --seo-radius: 12px;
  --seo-shadow: 0 4px 16px rgba(0,0,0,0.04);
  --seo-transition: 0.25s ease;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ---- 顶部条 ---- */
.seo-topbar {
  background: #f8fafc;
  border-bottom: 1px solid var(--seo-border);
  font-size: 0.85rem;
  padding: 8px 0;
  color: var(--seo-text-soft);
}
.seo-topbar__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
}
.seo-topbar__brand {
  font-weight: 600;
  color: var(--seo-primary);
  letter-spacing: 0.5px;
}
.seo-topbar__links {
  display: flex;
  gap: 16px;
}
.seo-topbar__links a {
  color: var(--seo-text-soft);
  text-decoration: none;
  transition: color var(--seo-transition);
}
.seo-topbar__links a:hover {
  color: var(--seo-primary);
}

/* ---- Logo + 搜索 ---- */
.seo-main {
  background: var(--seo-bg);
  padding: 24px 0;
  border-bottom: 1px solid var(--seo-border);
}
.seo-main__row {
  display: flex;
  align-items: center;
  gap: 40px;
}
.seo-logo img {
  height: 48px;
  width: auto;
  display: block;
}

.seo-search {
  flex: 1;
  max-width: 500px;
  margin-left: auto;
}
.seo-search__form {
  display: flex;
  background: #f1f5f9;
  border: 1px solid var(--seo-border);
  border-radius: 50px;
  overflow: hidden;
  transition: border-color var(--seo-transition), box-shadow var(--seo-transition);
}
.seo-search__form:focus-within {
  border-color: var(--seo-primary);
  box-shadow: 0 0 0 3px rgba(26,95,220,0.1);
}
.seo-search__input {
  flex: 1;
  height: 44px;
  padding: 0 20px;
  background: transparent;
  border: none;
  outline: none;
  color: var(--seo-text);
  font-size: 0.95rem;
}
.seo-search__input::placeholder {
  color: var(--seo-text-light);
}
.seo-search__btn {
  height: 44px;
  padding: 0 28px;
  background: var(--seo-primary);
  border: none;
  color: #fff;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  letter-spacing: 0.5px;
  transition: background var(--seo-transition);
}
.seo-search__btn:hover {
  background: var(--seo-primary-dark);
}

/* ---- 主导航 ---- */
.seo-nav {
  background: var(--seo-bg);
  border-bottom: 1px solid var(--seo-border);
  position: relative;
}
.seo-nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.seo-burger {
  display: none;
  flex-direction: column;
  gap: 5px;
  width: 44px;
  height: 44px;
  background: transparent;
  border: 1px solid var(--seo-border);
  border-radius: var(--seo-radius);
  cursor: pointer;
  padding: 10px;
}
.seo-burger span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--seo-primary);
  border-radius: 2px;
  transition: var(--seo-transition);
}

.seo-nav__list {
  list-style: none;
  display: flex;
  align-items: center;
  margin: 0;
  padding: 0;
  gap: 6px;
}
.seo-nav__item {
  position: relative;
}
.seo-nav__item a {
  display: block;
  padding: 16px 20px;
  color: var(--seo-text);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.95rem;
  border-radius: var(--seo-radius);
  transition: all var(--seo-transition);
}
.seo-nav__item a:hover {
  color: var(--seo-primary);
  background: #f0f4ff;
}
.seo-nav__item.active > a {
  color: var(--seo-primary);
  font-weight: 600;
  background: transparent;
  box-shadow: inset 0 -3px 0 var(--seo-primary);
}

.seo-nav__arrow {
  display: inline-block;
  width: 12px;
  height: 12px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  margin-left: 4px;
  transition: transform var(--seo-transition);
}
.seo-nav__item--has-sub:hover .seo-nav__arrow {
  transform: rotate(180deg);
}

/* 下拉菜单 */
.seo-dropdown {
  position: absolute;
  top: 100%;
  left: 0;
  background: #fff;
  border: 1px solid var(--seo-border);
  border-radius: var(--seo-radius);
  box-shadow: 0 12px 28px rgba(0,0,0,0.08);
  padding: 8px 0;
  min-width: 170px;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: all var(--seo-transition);
  z-index: 200;
  list-style: none;
}
.seo-nav__item--has-sub:hover .seo-dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.seo-dropdown li a {
  display: block;
  padding: 10px 20px;
  color: var(--seo-text);
  font-size: 0.9rem;
  white-space: nowrap;
}
.seo-dropdown li a:hover {
  background: #f0f4ff;
  color: var(--seo-primary);
}

.seo-nav__sitemap {
  padding: 8px 20px;
  background: #f0f4ff;
  border: 1px solid var(--seo-primary);
  border-radius: 30px;
  color: var(--seo-primary);
  font-size: 0.85rem;
  text-decoration: none;
  font-weight: 500;
  transition: all var(--seo-transition);
}
.seo-nav__sitemap:hover {
  background: var(--seo-primary);
  color: #fff;
}

/* ---- 移动端 ---- */
@media (max-width: 768px) {
  .seo-main__row {
    flex-wrap: wrap;
    gap: 16px;
  }
  .seo-search {
    max-width: 100%;
    width: 100%;
    order: 3;
  }
  .seo-burger {
    display: flex;
  }
  .seo-nav__list {
    display: none;
    flex-direction: column;
    width: 100%;
    background: #fff;
    position: absolute;
    top: 100%;
    left: 0;
    border-top: 1px solid var(--seo-border);
    box-shadow: 0 12px 24px rgba(0,0,0,0.06);
    z-index: 300;
    padding: 10px 0;
  }
  .seo-nav__list.open {
    display: flex;
  }
  .seo-nav__item a {
    padding: 14px 24px;
  }
  .seo-dropdown {
    position: static;
    box-shadow: none;
    border: none;
    padding-left: 20px;
    opacity: 1;
    visibility: visible;
    transform: none;
    display: none;
  }
  .seo-nav__item--has-sub.active .seo-dropdown {
    display: block;
  }
  .seo-nav__sitemap {
    display: none;
  }
}