header {
  padding-top: 8px;  /* 添加顶部间距 */
  background-color: var(--bg-primary);
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 16px;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}


/* shared-nav.css - 导航栏通用样式 */
.logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-primary);
  text-decoration: none;
}
.header-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
}
nav ul {
  display: flex;
  list-style: none;
  gap: 24px;
}
nav li {
  position: relative;
}
nav > ul > li > a {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border-radius: 6px;
  transition: var(--transition);
  color: var(--text-primary);
  text-decoration: none;
  font-weight: 500;
}
nav a:hover {
  color: var(--accent-color);
  background: var(--bg-tertiary);
}
.dropdown {
  position: relative;
}
.dropdown-content {
  position: absolute;
  top: 100%;
  left: 0;
  width: 240px;
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  box-shadow: var(--dropdown-shadow);
  padding: 12px 0;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: var(--transition);
  z-index: 100;
  display: grid;
  grid-template-columns: 1fr;
  gap: 4px;
}
.dropdown-content a {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 16px;
  color: var(--text-primary);
  transition: var(--transition);
  font-size: 0.95rem;
  border-left: 3px solid transparent;
  text-decoration: none;
}
.dropdown-content a:hover {
  background-color: var(--bg-tertiary);
  color: var(--accent-color);
  border-left: 3px solid var(--accent-color);
}
.dropdown:hover .dropdown-content {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.dropdown-arrow {
  font-size: 0.8rem;
  transition: transform 0.3s ease;
}
.dropdown:hover .dropdown-arrow {
  transform: rotate(180deg);
}
.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--text-secondary);
  font-size: 1.2rem;
  transition: var(--transition);
  padding: 8px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
}
.theme-toggle:hover {
  color: var(--accent-color);
  background: var(--bg-tertiary);
}
@media (max-width: 768px) {
  .header-content {
    flex-direction: column;
    gap: 15px;
  }
  nav ul {
    gap: 10px;
    flex-wrap: wrap;
    justify-content: center;
  }
}