/**
 * Navigation Styles - 重构版
 * 
 * 显示逻辑状态机：
 * ┌─────────────────────────────────────────────────────────────────────┐
 * │                        移动端导航状态                                │
 * ├─────────────────────────────────────────────────────────────────────┤
 * │                                                                     │
 * │  [状态1: 默认/顶部]                                                  │
 * │  ├── 条件: 页面未滚动 && 菜单未打开                                   │
 * │  ├── 导航栏: 透明背景                                                │
 * │  ├── Logo: 浅色版本                                                  │
 * │  ├── 汉堡按钮: 白色                                                  │
 * │  └── 语言按钮: 白色边框                                              │
 * │                                                                     │
 * │  [状态2: 滚动后]                                                     │
 * │  ├── 条件: 页面已滚动 && 菜单未打开                                   │
 * │  ├── 导航栏: 白色背景 + 模糊 + 阴影                                   │
 * │  ├── Logo: 深色版本                                                  │
 * │  ├── 汉堡按钮: 深色                                                  │
 * │  └── 语言按钮: 深色边框                                              │
 * │                                                                     │
 * │  [状态3: 菜单打开]                                                   │
 * │  ├── 条件: 菜单已打开 (无论是否滚动)                                  │
 * │  ├── 导航栏: 透明背景 (覆盖在菜单上方)                                │
 * │  ├── Logo: 浅色版本 (因为菜单是深色背景)                              │
 * │  ├── 关闭按钮(X): 白色                                               │
 * │  └── 语言按钮: 白色边框                                              │
 * │                                                                     │
 * └─────────────────────────────────────────────────────────────────────┘
 * 
 * Z-Index层级：
 * - 导航栏 (.nav): 1000
 * - 移动菜单 (.mobile-menu): 900
 * - 菜单打开时导航栏 (.nav.menu-open): 1000 (保持在菜单上方)
 * 
 * @package Saifeng
 * @since 2.4.0
 */

/* ===== CSS变量定义 ===== */
:root {
    --nav-height: 80px;
    --nav-height-mobile: 70px;
    --nav-height-small: 60px;
    --nav-transition: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
    --menu-transition: 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ===== 基础导航样式 ===== */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    padding: 0 80px;
    height: var(--nav-height);
    display: flex;
    align-items: center;
    justify-content: space-between;
    transition: background var(--nav-transition),
                box-shadow var(--nav-transition),
                backdrop-filter var(--nav-transition);
    
    /* 状态1: 默认透明 */
    background: transparent;
    backdrop-filter: none;
    box-shadow: none;
}

/* ===== 状态2: 滚动后 - 白色背景 ===== */
.nav.scrolled {
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(20px);
    box-shadow: 0 2px 40px rgba(30, 80, 230, 0.1);
}

/* ===== 状态3: 菜单打开 - 强制透明 ===== */
.nav.menu-open {
    background: transparent !important;
    backdrop-filter: none !important;
    box-shadow: none !important;
}

/* ===== LOGO容器 ===== */
.nav-logo {
    display: flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
    position: relative;
    z-index: 1;
}

/* 所有Logo图片的基础样式 */
.nav-logo img {
    height: auto;
    display: block;
    transition: opacity var(--nav-transition);
}

/* ===== LOGO显示逻辑 - 桌面端 ===== */
@media (min-width: 769px) {
    /* 隐藏所有移动端logo */
    .nav-logo .logo-mobile,
    .nav-logo .logo-mobile-light,
    .nav-logo .logo-mobile-dark {
        display: none !important;
    }
    
    /* 状态1: 默认 - 显示浅色logo */
    .nav-logo .logo-light { display: block; }
    .nav-logo .logo-dark { display: none; }
    
    /* 状态2: 滚动后 - 显示深色logo */
    .nav.scrolled .nav-logo .logo-light { display: none; }
    .nav.scrolled .nav-logo .logo-dark { display: block; }
    
    /* Solid模式(非首页等) - 显示深色logo */
    .nav.solid .nav-logo .logo-light { display: none; }
    .nav.solid .nav-logo .logo-dark { display: block; }
}

/* ===== LOGO显示逻辑 - 移动端 ===== */
@media (max-width: 768px) {
    /* 隐藏所有桌面端logo */
    .nav-logo .logo-desktop,
    .nav-logo .logo-light.logo-desktop,
    .nav-logo .logo-dark.logo-desktop {
        display: none !important;
    }
    
    /* 状态1: 默认 - 显示浅色移动端logo */
    .nav-logo .logo-mobile-light { display: block; }
    .nav-logo .logo-mobile-dark { display: none; }
    
    /* 状态2: 滚动后 - 显示深色移动端logo */
    .nav.scrolled .nav-logo .logo-mobile-light { display: none; }
    .nav.scrolled .nav-logo .logo-mobile-dark { display: block; }
    
    /* 状态3: 菜单打开 - 强制显示浅色logo (因为菜单是深色背景) */
    .nav.menu-open .nav-logo .logo-mobile-light { display: block !important; }
    .nav.menu-open .nav-logo .logo-mobile-dark { display: none !important; }
    
    /* Solid模式 - 显示深色移动端logo */
    .nav.solid .nav-logo .logo-mobile-light { display: none; }
    .nav.solid .nav-logo .logo-mobile-dark { display: block; }
    
    /* Solid + 菜单打开 - 仍然显示浅色logo */
    .nav.solid.menu-open .nav-logo .logo-mobile-light { display: block !important; }
    .nav.solid.menu-open .nav-logo .logo-mobile-dark { display: none !important; }
}

/* 文字Logo备用方案 */
.nav-logo-icon {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, #1e50e6, #25bdff);
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 16px;
    font-weight: bold;
    flex-shrink: 0;
}

.nav-logo-text {
    font-family: 'Oswald', sans-serif;
    font-size: 24px;
    font-weight: 700;
    color: var(--white);
    letter-spacing: 0.1em;
    transition: color var(--nav-transition);
}

.nav.scrolled .nav-logo-text,
.nav.solid .nav-logo-text {
    color: var(--dark-blue);
}

.nav.menu-open .nav-logo-text {
    color: var(--white) !important;
}

/* ===== 导航菜单 (桌面端) ===== */
.nav-menu {
    display: flex;
    align-items: center;
    gap: 40px;
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav-menu > li {
    position: relative;
}

.nav-link {
    font-size: 13px;
    font-weight: 500;
    color: var(--white);
    text-decoration: none;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    transition: color 0.3s ease;
    position: relative;
    display: flex;
    align-items: center;
    gap: 6px;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient-bright);
    transition: width 0.3s ease;
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

/* 滚动后/Solid模式 - 链接变深色 */
.nav.scrolled .nav-link,
.nav.solid .nav-link {
    color: var(--gray-800);
}

.nav.scrolled .nav-link:hover,
.nav.solid .nav-link:hover {
    color: var(--electric-blue);
}

/* ===== 下拉菜单 (桌面端) ===== */
.nav-link .dropdown-arrow {
    width: 10px;
    height: 10px;
    stroke: currentColor;
    stroke-width: 2;
    fill: none;
    transition: transform 0.3s ease;
}

.nav-menu > li:hover .dropdown-arrow,
.nav-menu > li.keyboard-open .dropdown-arrow {
    transform: rotate(180deg);
}

.nav-menu .sub-menu {
    position: absolute;
    top: calc(100% + 10px);
    left: 50%;
    transform: translateX(-50%) translateY(10px);
    min-width: 160px;
    background: var(--white);
    border-radius: 8px;
    padding: 8px;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.12);
    z-index: 1001;
    list-style: none;
    margin: 0;
}

/* 悬停桥接区域 */
.nav-menu .sub-menu::before {
    content: '';
    position: absolute;
    top: -15px;
    left: 0;
    right: 0;
    height: 15px;
}

.nav-menu > li:hover > .sub-menu,
.nav-menu > li.keyboard-open > .sub-menu {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}

.nav-menu .sub-menu .sub-menu-link {
    display: block;
    padding: 10px 16px;
    font-size: 14px;
    font-weight: 400;
    color: var(--gray-700);
    text-decoration: none;
    transition: all 0.2s ease;
    border-radius: 4px;
    white-space: nowrap;
}

.nav-menu .sub-menu .sub-menu-link:hover,
.nav-menu .sub-menu .sub-menu-link.active {
    color: var(--electric-blue);
    background: var(--gray-50);
}

/* ===== 导航操作区 ===== */
.nav-actions {
    display: flex;
    align-items: center;
    gap: 16px;
}

/* ===== CTA按钮 ===== */
.nav-cta {
    padding: 12px 28px;
    background: transparent;
    border: 1px solid rgba(255, 255, 255, 0.4);
    color: var(--white);
    font-size: 13px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    border-radius: 4px;
}

.nav-cta:hover {
    background: var(--white);
    color: var(--dark-blue);
    border-color: var(--white);
}

/* 滚动后CTA样式 */
.nav.scrolled .nav-cta,
.nav.solid .nav-cta {
    background: var(--electric-blue);
    color: var(--white);
    border-color: var(--electric-blue);
}

.nav.scrolled .nav-cta:hover,
.nav.solid .nav-cta:hover {
    background: #1a44c4;
    border-color: #1a44c4;
}

/* CTA样式变体 - Outline */
.nav.scrolled[data-cta-style-scrolled="outline"] .nav-cta,
.nav.solid[data-cta-style="outline"] .nav-cta {
    background: transparent;
    border: 2px solid var(--electric-blue);
    color: var(--electric-blue);
}

.nav.scrolled[data-cta-style-scrolled="outline"] .nav-cta:hover,
.nav.solid[data-cta-style="outline"] .nav-cta:hover {
    background: var(--electric-blue);
    color: var(--white);
}

/* CTA样式变体 - Gradient */
.nav[data-cta-style="gradient"] .nav-cta,
.nav.scrolled[data-cta-style-scrolled="gradient"] .nav-cta {
    background: linear-gradient(135deg, var(--electric-blue), var(--cyan-glow));
    border: none;
    color: var(--white);
}

/* ===== 语言切换器 ===== */
.lang-switcher {
    position: relative;
}

.lang-btn {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.3s ease;
}

.lang-btn svg {
    width: 18px;
    height: 18px;
    stroke: var(--white);
    stroke-width: 1.5;
    fill: none;
    transition: stroke 0.3s ease;
}

.lang-btn:hover {
    background: rgba(255, 255, 255, 0.2);
}

/* 滚动后语言按钮 */
.nav.scrolled .lang-btn,
.nav.solid .lang-btn {
    background: var(--gray-100);
    border-color: var(--gray-200);
}

.nav.scrolled .lang-btn svg,
.nav.solid .lang-btn svg {
    stroke: var(--gray-600);
}

.nav.scrolled .lang-btn:hover,
.nav.solid .lang-btn:hover {
    background: var(--electric-blue);
    border-color: var(--electric-blue);
}

.nav.scrolled .lang-btn:hover svg,
.nav.solid .lang-btn:hover svg {
    stroke: var(--white);
}

/* 菜单打开时语言按钮 - 恢复白色样式 */
.nav.menu-open .lang-btn {
    background: rgba(255, 255, 255, 0.1) !important;
    border-color: rgba(255, 255, 255, 0.2) !important;
}

.nav.menu-open .lang-btn svg {
    stroke: var(--white) !important;
}

/* 语言下拉菜单 */
.lang-dropdown {
    position: absolute;
    top: calc(100% + 10px);
    right: 0;
    min-width: 140px;
    background: var(--white);
    border-radius: 10px;
    padding: 8px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all 0.3s ease;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.15);
    z-index: 100;
}

.lang-switcher:hover .lang-dropdown,
.lang-switcher.active .lang-dropdown {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.lang-option {
    display: block;
    padding: 10px 14px;
    font-size: 13px;
    color: var(--gray-600);
    border-radius: 6px;
    text-decoration: none;
    transition: all 0.2s ease;
    cursor: pointer;
}

.lang-option:hover {
    background: var(--gray-100);
    color: var(--gray-800);
}

.lang-option.active {
    color: var(--electric-blue);
    font-weight: 500;
}

/* 未安装插件时的提示 */
.lang-option-notice {
    display: block;
    padding: 12px 14px;
    font-size: 12px;
    color: var(--gray-500);
    text-align: center;
    white-space: nowrap;
}

/* ===== 汉堡菜单按钮 ===== */
.nav-mobile-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    padding: 8px;
    background: none;
    border: none;
    position: relative;
    z-index: 1;
}

.nav-mobile-toggle span {
    width: 24px;
    height: 2px;
    background: var(--white);
    transition: all 0.3s ease;
    display: block;
}

/* 滚动后汉堡按钮变深色 */
.nav.scrolled .nav-mobile-toggle span,
.nav.solid .nav-mobile-toggle span {
    background: var(--dark-blue);
}

/* 菜单打开时 - X形状 + 白色 */
.nav.menu-open .nav-mobile-toggle span {
    background: var(--white) !important;
}

.nav-mobile-toggle.active span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.nav-mobile-toggle.active span:nth-child(2) {
    opacity: 0;
}

.nav-mobile-toggle.active span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}


/* ============================================================
   移动端全屏覆盖菜单
   ============================================================ */
.mobile-menu {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh;
    height: 100dvh; /* 动态视口高度，解决移动端地址栏问题 */
    background: linear-gradient(135deg, var(--dark-blue) 0%, var(--darker-blue) 100%);
    z-index: 900; /* 低于导航栏，让导航栏显示在上面 */
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: var(--nav-height-mobile) 20px 40px;
    box-sizing: border-box;
    
    /* 初始隐藏状态 */
    opacity: 0;
    visibility: hidden;
    transform: translateY(-100%);
    transition: opacity var(--menu-transition),
                visibility var(--menu-transition),
                transform var(--menu-transition);
}

/* 菜单打开状态 */
.mobile-menu.active {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

/* ===== 移动端菜单列表 ===== */
.mobile-nav-list {
    list-style: none;
    text-align: center;
    margin: 0;
    padding: 0;
    width: 100%;
    max-width: 400px;
}

.mobile-nav-list > li {
    position: relative;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.mobile-nav-list > li:last-child {
    border-bottom: none;
}

/* 一级菜单链接 */
.mobile-nav-link {
    display: block;
    font-size: 20px;
    font-weight: 400;
    color: var(--white);
    letter-spacing: 0.05em;
    padding: 18px 0;
    text-decoration: none;
    transition: color 0.3s ease, transform 0.3s ease;
    
    /* 入场动画初始状态 */
    opacity: 0;
    transform: translateY(20px);
}

.mobile-menu.active .mobile-nav-link {
    opacity: 1;
    transform: translateY(0);
}

/* 入场动画延迟 */
.mobile-menu.active .mobile-nav-list > li:nth-child(1) .mobile-nav-link { transition-delay: 0.1s; }
.mobile-menu.active .mobile-nav-list > li:nth-child(2) .mobile-nav-link { transition-delay: 0.15s; }
.mobile-menu.active .mobile-nav-list > li:nth-child(3) .mobile-nav-link { transition-delay: 0.2s; }
.mobile-menu.active .mobile-nav-list > li:nth-child(4) .mobile-nav-link { transition-delay: 0.25s; }
.mobile-menu.active .mobile-nav-list > li:nth-child(5) .mobile-nav-link { transition-delay: 0.3s; }
.mobile-menu.active .mobile-nav-list > li:nth-child(6) .mobile-nav-link { transition-delay: 0.35s; }
.mobile-menu.active .mobile-nav-list > li:nth-child(7) .mobile-nav-link { transition-delay: 0.4s; }
.mobile-menu.active .mobile-nav-list > li:nth-child(8) .mobile-nav-link { transition-delay: 0.45s; }

.mobile-nav-link:hover,
.mobile-nav-link:active {
    color: var(--cyan-glow);
}

/* ===== 移动端二级菜单 ===== */
.mobile-has-dropdown {
    position: relative;
}

/* 有子菜单的一级链接 - 使用flex布局 */
.mobile-has-dropdown > .mobile-nav-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

/* 下拉切换按钮 */
.mobile-dropdown-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 10px;
    cursor: pointer;
    color: var(--white);
    transition: transform 0.3s ease;
}

.mobile-dropdown-toggle svg {
    width: 14px;
    height: 14px;
    stroke: currentColor;
    stroke-width: 2;
    fill: none;
}

.mobile-has-dropdown.open .mobile-dropdown-toggle {
    transform: rotate(180deg);
}

/* 二级菜单容器 */
.mobile-sub-menu {
    list-style: none;
    margin: 0;
    padding: 0;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 8px;
    overflow: hidden;
    
    /* 折叠状态 */
    max-height: 0;
    opacity: 0;
    transition: max-height 0.4s ease, opacity 0.3s ease;
}

.mobile-has-dropdown.open .mobile-sub-menu {
    max-height: 500px;
    opacity: 1;
}

/* 二级菜单链接 */
.mobile-sub-link {
    display: block;
    font-size: 16px;
    font-weight: 300;
    color: rgba(255, 255, 255, 0.8);
    padding: 14px 24px;
    text-decoration: none;
    transition: all 0.3s ease;
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.mobile-sub-link:last-child {
    border-bottom: none;
}

.mobile-sub-link:hover,
.mobile-sub-link:active,
.mobile-sub-link.active {
    color: var(--cyan-glow);
    background: rgba(255, 255, 255, 0.05);
}

/* 二级菜单项入场动画 */
.mobile-sub-menu li {
    opacity: 0;
    transform: translateY(-10px);
    transition: opacity 0.3s ease, transform 0.3s ease;
}

.mobile-has-dropdown.open .mobile-sub-menu li {
    opacity: 1;
    transform: translateY(0);
}

.mobile-has-dropdown.open .mobile-sub-menu li:nth-child(1) { transition-delay: 0.05s; }
.mobile-has-dropdown.open .mobile-sub-menu li:nth-child(2) { transition-delay: 0.1s; }
.mobile-has-dropdown.open .mobile-sub-menu li:nth-child(3) { transition-delay: 0.15s; }
.mobile-has-dropdown.open .mobile-sub-menu li:nth-child(4) { transition-delay: 0.2s; }
.mobile-has-dropdown.open .mobile-sub-menu li:nth-child(5) { transition-delay: 0.25s; }


/* ============================================================
   响应式布局
   ============================================================ */

/* 平板及以下 - 隐藏桌面菜单，显示汉堡按钮 */
@media (max-width: 992px) {
    .nav-menu {
        display: none;
    }
    
    .nav-cta {
        display: none;
    }
    
    .nav-mobile-toggle {
        display: flex;
    }
}

/* 中等屏幕 */
@media (max-width: 1200px) {
    .nav {
        padding: 0 40px;
    }
    
    .nav-menu {
        gap: 30px;
    }
}

/* 平板 */
@media (max-width: 768px) {
    .nav {
        padding: 0 20px;
        height: var(--nav-height-mobile);
    }
    
    .lang-btn {
        width: 36px;
        height: 36px;
    }
    
    .mobile-menu {
        padding-top: var(--nav-height-mobile);
    }
    
    .mobile-nav-link {
        font-size: 18px;
        padding: 16px 0;
    }
    
    .mobile-sub-link {
        font-size: 15px;
        padding: 12px 20px;
    }
}

/* 手机 */
@media (max-width: 480px) {
    .nav {
        padding: 0 16px;
        height: var(--nav-height-small);
    }
    
    .mobile-menu {
        padding-top: var(--nav-height-small);
    }
    
    .mobile-nav-link {
        font-size: 17px;
        padding: 14px 0;
    }
    
    .mobile-sub-link {
        font-size: 14px;
        padding: 12px 16px;
    }
}


/* ============================================================
   Solid模式 (非首页等不需要透明背景的页面)
   ============================================================ */
.nav.solid {
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(20px);
    box-shadow: 0 2px 40px rgba(30, 80, 230, 0.08);
}


/* ============================================================
   安全区域适配 (iPhone刘海屏等)
   ============================================================ */
@supports (padding-top: env(safe-area-inset-top)) {
    .nav {
        padding-top: env(safe-area-inset-top);
    }
    
    .mobile-menu {
        padding-top: calc(var(--nav-height-mobile) + env(safe-area-inset-top));
        padding-bottom: env(safe-area-inset-bottom);
    }
}


/* ============================================================
   无障碍访问
   ============================================================ */

/* 焦点样式 - 仅保留必要的无障碍样式 */
.nav-cta:focus-visible,
.lang-btn:focus-visible {
    outline: 2px solid var(--electric-blue);
    outline-offset: 2px;
}

/* 导航链接焦点样式 - 使用focus-visible确保键盘导航可见 */
.nav-link:focus-visible,
.mobile-nav-link:focus-visible,
.mobile-sub-link:focus-visible {
    outline: 2px solid var(--electric-blue);
    outline-offset: 2px;
}

/* 鼠标点击不显示焦点轮廓 */
.nav-link:focus:not(:focus-visible),
.mobile-nav-link:focus:not(:focus-visible),
.mobile-sub-link:focus:not(:focus-visible) {
    outline: none;
}

/* 减少动画 (用户偏好) */
@media (prefers-reduced-motion: reduce) {
    .nav,
    .nav-logo img,
    .mobile-menu,
    .mobile-nav-link,
    .mobile-sub-menu,
    .mobile-sub-menu li {
        transition: none;
    }
}