/* ============================================
   Navigation - 导航栏样式
   ============================================ */

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  z-index: 1000;
  transition: all var(--transition-base);
  background: transparent;
}

/* 滚动后的导航栏 */
.nav.scrolled {
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-primary);
  box-shadow: 0 4px 24px rgba(15, 23, 42, 0.08);
}

.nav__container {
  max-width: var(--container-max);
  height: 100%;
  margin: 0 auto;
  padding: 0 var(--container-padding);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* ===== Logo ===== */
.nav__logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  text-decoration: none;
  z-index: 1001;
}

.nav__logo-icon {
  width: auto;
  height: 36px;
  object-fit: contain;
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.nav__logo-text {
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: 0.02em;
}

.nav__logo-text span {
  color: var(--color-primary);
}

/* ===== 导航菜单 ===== */
.nav__menu {
  display: flex;
  align-items: center;
  gap: var(--space-8);
}

.nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-6);
}

.nav__link {
  position: relative;
  font-size: var(--text-base);
  color: var(--text-secondary);
  text-decoration: none;
  padding: var(--space-2) 0;
  transition: color var(--transition-fast);
}

.nav__link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 0;
  height: 2px;
  background: var(--gradient-primary);
  border-radius: var(--radius-full);
  transition: width var(--transition-base);
}

.nav__link:hover {
  color: var(--text-primary);
}

.nav__link:hover::after {
  width: 100%;
}

.nav__link.nav-active {
  color: var(--color-primary);
}

.nav__link.nav-active::after {
  width: 100%;
}

/* ===== CTA 按钮 ===== */
.nav__cta {
  padding: var(--space-2) var(--space-5);
  font-size: var(--text-sm);
  font-weight: 600;
  background: var(--gradient-primary);
  color: var(--text-inverse);
  border-radius: var(--radius-md);
  text-decoration: none;
  transition: all var(--transition-base);
  box-shadow: 0 2px 12px rgba(37, 99, 235, 0.25);
}

.nav__cta:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 20px rgba(37, 99, 235, 0.35);
  color: var(--text-inverse);
}

/* ===== 汉堡菜单按钮 ===== */
.nav__toggle {
  display: none;
  flex-direction: column;
  justify-content: space-between;
  width: 28px;
  height: 22px;
  background: transparent;
  cursor: pointer;
  z-index: 1001;
}

.nav__toggle span {
  display: block;
  width: 100%;
  height: 2px;
  background: var(--text-primary);
  border-radius: var(--radius-full);
  transition: all var(--transition-base);
  transform-origin: center;
}

.nav__toggle.active span:nth-child(1) {
  transform: translateY(10px) rotate(45deg);
  background: var(--color-primary);
}

.nav__toggle.active span:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}

.nav__toggle.active span:nth-child(3) {
  transform: translateY(-10px) rotate(-45deg);
  background: var(--color-primary);
}

/* ===== 移动端遮罩 ===== */
.nav__overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(255, 255, 255, 0.97);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  z-index: 999;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-base);
}

.nav__overlay.active {
  opacity: 1;
  visibility: visible;
}

.nav__overlay-menu {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  gap: var(--space-6);
}

.nav__overlay-menu .nav__link {
  font-size: var(--text-2xl);
  color: var(--text-primary);
  padding: var(--space-2) 0;
}

.nav__overlay-menu .nav__link.nav-active {
  color: var(--color-primary);
}

.nav__overlay-menu .nav__cta {
  margin-top: var(--space-4);
  padding: var(--space-3) var(--space-8);
  font-size: var(--text-base);
}

/* ===== 响应式 ===== */
@media (max-width: 768px) {
  .nav {
    height: var(--nav-height-mobile);
  }

  .nav__menu {
    display: none;
  }

  .nav__toggle {
    display: flex;
  }

  .nav__overlay {
    display: block;
  }

  .nav__logo-text {
    font-size: var(--text-base);
  }
}