/* 页头专用样式 */
.pc-nav { display: block; }
.mobile-nav { display: none; }

/* 4. 导航栏：精密结构重构 */
.site-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: var(--header-h);
    background: var(--bg);
    z-index: 2000;
    transition: height 0.6s var(--ease-dynamic), 
                background 0.6s var(--ease-dynamic),
                border-color 0.6s var(--ease-dynamic);
    border-bottom: 1px solid transparent;
}

.site-header .container {
    height: 100%;
}

.site-header::before {
    content: '';
    position: absolute;
    inset: 0;
    background: var(--bg);
    opacity: 0;
    transition: opacity 0.6s var(--ease-dynamic);
    z-index: -1;
}

.site-header.is-scrolled {
    height: var(--header-h-sm);
    border-bottom-color: var(--border);
}

.site-header.is-scrolled::before {
    opacity: 0.98;
    backdrop-filter: blur(20px);
}

.nav-wrapper {
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: relative;
    padding: 0 10px;
}

/* 徕卡精密取景框边角 - 增强版 */
.nav-wrapper::before,
.nav-wrapper::after {
    content: '';
    position: absolute;
    width: 16px;
    height: 16px;
    border-color: var(--border);
    border-style: solid;
    opacity: 0.4;
    transition: all 0.6s var(--ease-dynamic);
    pointer-events: none;
    z-index: 10;
}

.nav-wrapper::before {
    top: 15px;
    left: -5px;
    border-width: 1.5px 0 0 1.5px;
}

.nav-wrapper::after {
    bottom: 15px;
    right: -5px;
    border-width: 0 1.5px 1.5px 0;
}

.site-header.is-scrolled .nav-wrapper::before { 
    top: 10px; 
    left: 0;
    opacity: 0.8; 
    width: 12px;
    height: 12px;
}

.site-header.is-scrolled .nav-wrapper::after { 
    bottom: 10px; 
    right: 0;
    opacity: 0.8; 
    width: 12px;
    height: 12px;
}

/* Logo：精密品牌核心 */
.logo-link {
    display: flex;
    align-items: center;
    gap: 16px;
}

.logo-circle {
    width: 12px;
    height: 12px;
    background: var(--leica-red);
    border-radius: 50%;
    transition: transform 0.4s var(--ease-dynamic), 
                box-shadow 0.4s var(--ease-dynamic);
    flex-shrink: 0;
    position: relative;
}

/* 红点呼吸感 */
.logo-circle::before {
    content: '';
    position: absolute;
    inset: -4px;
    border: 1px solid var(--leica-red);
    border-radius: 50%;
    opacity: 0;
    transition: all 0.4s var(--ease-dynamic);
}

.logo-link:hover .logo-circle {
    transform: scale(1.2);
    box-shadow: 0 0 15px rgba(212, 0, 0, 0.6);
}

.logo-link:hover .logo-circle::before {
    inset: -6px;
    opacity: 0.3;
}

.logo-text {
    font-size: 16px;
    font-weight: 900;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--fg);
    transition: letter-spacing 0.4s var(--ease-dynamic);
}

.logo-link:hover .logo-text {
    letter-spacing: 0.15em;
    color: var(--accent);
}

/* 导航菜单：精密机械对齐 */
.nav-menu ul {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-menu a {
    font-size: 12px;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    padding: 10px 0;
    position: relative;
    opacity: 0.6;
    transition: opacity 0.3s var(--ease-dynamic),
                color 0.3s var(--ease-dynamic),
                transform 0.3s var(--ease-dynamic);
    display: block;
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 1.5px;
    background: var(--accent);
    transform: scaleX(0);
    transform-origin: right;
    transition: transform 0.4s var(--ease-dynamic);
}

.nav-menu a:hover,
.nav-menu .active a {
    opacity: 1;
    color: var(--fg);
    transform: translateY(-1px);
}

.nav-menu a:hover::after,
.nav-menu .active a::after {
    transform: scaleX(1);
    transform-origin: left;
}

/* 功能按钮：机械按钮感 */
.nav-actions {
    display: flex;
    align-items: center;
    gap: 20px;
}

.btn-icon {
    background: var(--subtle-bg);
    border: 1px solid var(--border);
    color: var(--fg);
    padding: 6px 16px;
    height: 32px;
    font-size: 10px;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    cursor: pointer;
    transition: all 0.4s var(--ease-dynamic);
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 2px;
    position: relative;
    overflow: hidden;
}

.btn-icon::before {
    content: '';
    position: absolute;
    inset: 0;
    background: var(--fg);
    transform: translateY(100%);
    transition: transform 0.4s var(--ease-dynamic);
    z-index: -1;
}

.btn-icon:hover {
    color: var(--bg);
    border-color: var(--fg);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.btn-icon:hover::before {
    transform: translateY(0);
}

/* 移动端菜单切换：快门拨杆感 */
.mobile-toggle {
    display: none;
    width: 32px;
    height: 32px;
    position: relative;
    cursor: pointer;
    z-index: 2100;
}

.mobile-toggle span {
    display: block;
    width: 100%;
    height: 1.5px;
    background: var(--fg);
    position: absolute;
    left: 0;
    transition: all 0.4s var(--ease-dynamic);
}

.mobile-toggle span:nth-child(1) { top: 12px; }
.mobile-toggle span:nth-child(2) { top: 20px; width: 60%; left: 40%; }

.nav-open .mobile-toggle span:nth-child(1) { 
    transform: translateY(4px) rotate(45deg); 
    width: 100%; 
}
.nav-open .mobile-toggle span:nth-child(2) { 
    transform: translateY(-4px) rotate(-45deg); 
    width: 100%; 
    left: 0; 
}

@media (max-width: 992px) {
    .pc-nav { display: none; }
    .mobile-nav { 
        display: block;
        position: fixed;
        top: 0;
        right: -280px;
        width: 280px;
        height: 100vh;
        background: var(--bg);
        z-index: 3000;
        transition: right 0.4s cubic-bezier(0.19, 1, 0.22, 1);
        padding: 80px 30px;
        box-shadow: -10px 0 30px rgba(0,0,0,0.1);
    }
    
    body.nav-open .mobile-nav {
        right: 0;
    }
    
    .mobile-nav ul {
        list-style: none;
        flex-direction: column;
        gap: 24px;
        text-align: center;
        width: 100%;
    }
    
    .mobile-nav li {
        margin-bottom: 20px;
    }
    
    .mobile-nav a {
        font-size: 28px; 
        font-weight: 900; 
        letter-spacing: 0.05em; 
        padding: 15px 0;
        opacity: 0;
        transform: translateY(20px);
        transition: all 0.6s var(--ease-dynamic);
    }

    .nav-open .mobile-nav a {
        opacity: 1;
        transform: translateY(0);
    }

    /* 菜单项逐个进场动画 */
    .nav-open .mobile-nav li:nth-child(1) a { transition-delay: 0.1s; }
    .nav-open .mobile-nav li:nth-child(2) a { transition-delay: 0.2s; }
    .nav-open .mobile-nav li:nth-child(3) a { transition-delay: 0.3s; }
    .nav-open .mobile-nav li:nth-child(4) a { transition-delay: 0.4s; }
    .nav-open .mobile-nav li:nth-child(5) a { transition-delay: 0.5s; }
    
    .mobile-toggle { 
        display: block; 
    }
    
    .nav-actions { 
        gap: 16px;
    }
    
    .btn-icon {
        padding: 0 10px;
        height: 28px;
        font-size: 9px;
    }
}