.main-nav {
  width: 100%;
}

.main-header {
  background-color: #1890ff;
  color: #fff;
  padding: 15px 0;
  text-align: center;
}

.main-header h1 {
  margin: 0;
  font-size: 1.8rem;
  font-weight: 500;
}

.nav-tabs {
  display: flex;
  background-color: #fff;
  border-bottom: 1px solid #e8e8e8;
  padding: 0 20px;
}

.nav-tab {
  padding: 12px 20px;
  color: #666;
  text-decoration: none;
  font-size: 14px;
  font-weight: 500;
  position: relative;
  transition: all 0.3s;
}

.nav-tab:hover {
  color: #1890ff;
}

.nav-tab.active {
  color: #1890ff;
  font-weight: 600;
}

.nav-tab.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: #1890ff;
}