.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 44px;
  z-index: 999;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0 12px;
  box-sizing: border-box;
}

.header-nav-center {
  display: flex;
  justify-content: center;
  gap: 22px;
  align-items: center;
}

.nav-item {
  color: rgba(255,255,255,0.7);
  font-size: 16px;
  position: relative;
  cursor: pointer;
  white-space: nowrap;
}
.nav-item.active {
  color: #fff;
  font-weight: 500;
}
.nav-item.active::after {
  content: '';
  position: absolute;
  bottom: -6px;
  left: 50%;
  transform: translateX(-50%);
  width: 20px;
  height: 2px;
  background: #fff;
  border-radius: 1px;
}