:root {
    /* ------ 纯白北欧核心配色 (Clean Nordic Palette) ------ */
    --text-dark: #1d1d1f;       /* 主要文字 (Apple 级柔和深黑) */
    --text-gray: #86868b;       /* 次要描述信息 (高级中灰) */
    --text-light: #d2d2d7;      /* 极浅边线或辅助字 */
    --primary-color: #0071e3;   /* 极简科技蓝 */
    --primary-hover: #005bb5;   /* 悬停深蓝 */
    --accent-color: #06c;       /* 交互亮点 */

    /* 背景体系: 纯白与极浅冷暖灰构建无边框层级 */
    --bg-body: #ffffff;         /* 纯白主视窗 */
    --bg-warm: #fbfbfd;         /* 板块/卡片浅灰背景 */
    --bg-light: #f5f5f7;        /* 胶囊按钮、标签背景 */
    --bg-card-hover: #f0f0f3;

    /* 边框与圆角 (北欧大圆角无边框设计) */
    --border-color: #e5e5ea;
    --border-light: #f0f0f2;
    --border-radius-xl: 24px;
    --border-radius-lg: 18px;
    --border-radius-md: 12px;
    --border-radius-sm: 8px;

    /* 柔和弥散阴影 */
    --shadow-subtle: 0 4px 20px rgba(0, 0, 0, 0.03);
    --shadow-float: 0 10px 30px rgba(0, 0, 0, 0.06);
    --shadow-pop: 0 20px 50px rgba(0, 0, 0, 0.08);

    /* 布局宽度 */
    --container-max: 1280px;
}

/* 全局重置与排版 */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Inter", "SF Pro Text", "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-body);
    color: var(--text-dark);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

a {
    text-decoration: none;
    color: inherit;
    transition: all 0.25s ease;
}

img {
    max-width: 100%;
    display: block;
}

/* 容器通用类 */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 28px;
}

/* 1. 顶部纯白磨砂玻璃导航栏 (Solid Frameless Navbar) */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 76px;
    background: rgba(255, 255, 255, 0.92);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(0, 0, 0, 0.04);
    z-index: 1000;
    display: flex;
    align-items: center;
}

.navbar .nav-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
}

/* 端正大气的品牌 Logo */
.brand-logo {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
}

.brand-logo-icon {
    width: 36px;
    height: 36px;
    border-radius: 9px;
    display: block;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.12);
    transition: transform 0.25s cubic-bezier(0.165, 0.84, 0.44, 1), box-shadow 0.25s ease;
    flex-shrink: 0;
}

.brand-logo:hover .brand-logo-icon {
    transform: scale(1.06);
    box-shadow: 0 4px 14px rgba(0, 210, 255, 0.25);
}

.brand-text-group {
    display: flex;
    flex-direction: column;
    line-height: 1.15;
}

.brand-company {
    font-size: 1.05rem;
    font-weight: 700;
    letter-spacing: 0.8px;
    color: #1d1d1f;
}

.brand-subtext {
    font-size: 0.65rem;
    font-weight: 600;
    letter-spacing: 1.2px;
    color: #86868b;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 36px;
}

.nav-link {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-dark);
    position: relative;
    padding: 8px 0;
    display: inline-flex;
    align-items: center;
    gap: 4px;
}

.nav-link:hover, .nav-link.active {
    color: var(--primary-color);
}

/* 下拉菜单 (Dropdown) */
.nav-item-dropdown {
    position: relative;
    display: inline-flex;
    align-items: center;
}

.dropdown-chevron {
    display: inline-block;
    font-size: 1.1rem;
    line-height: 1;
    transform: rotate(90deg);
    transition: transform 0.25s ease;
    margin-left: 2px;
}

.nav-item-dropdown:hover .dropdown-chevron {
    transform: rotate(270deg);
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%) translateY(10px);
    min-width: 190px;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-radius: 14px;
    box-shadow: 0 12px 36px rgba(0, 0, 0, 0.09);
    border: 1px solid rgba(0, 0, 0, 0.04);
    padding: 8px;
    opacity: 0;
    visibility: hidden;
    transition: all 0.25s cubic-bezier(0.165, 0.84, 0.44, 1);
    pointer-events: none;
    z-index: 10001;
}

/* 垫片防止鼠标划出闪烁 */
.nav-item-dropdown::after {
    content: '';
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    height: 16px;
}

.nav-item-dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateX(-50%) translateY(4px);
}

.dropdown-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    padding: 10px 16px;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-dark);
    border-radius: 8px;
    transition: background 0.15s, color 0.15s;
    white-space: nowrap;
}

.dropdown-item:hover {
    background: var(--bg-light);
    color: var(--primary-color);
}

.dropdown-item-count {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-gray);
    background: var(--bg-light);
    padding: 2px 8px;
    border-radius: 10px;
    transition: all 0.15s ease;
}

.dropdown-item:hover .dropdown-item-count {
    background: #e8f2ff;
    color: var(--primary-color);
}

.dropdown-sep {
    height: 1px;
    background: var(--border-light);
    margin: 4px 8px;
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 16px;
}

.btn-rfq {
    background: var(--text-dark);
    color: #ffffff !important;
    padding: 9px 22px;
    border-radius: 20px;
    font-size: 0.88rem;
    font-weight: 600;
    transition: transform 0.2s, background 0.2s;
    display: inline-flex;
    align-items: center;
}

.btn-rfq:hover {
    background: #000000;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.mobile-menu-btn {
    display: none;
    font-size: 1.6rem;
    cursor: pointer;
    background: none;
    border: none;
    color: var(--text-dark);
    padding: 4px;
}

/* 2. 页面主体上部留白 */
.page-offset {
    padding-top: 96px;
}

/* 3. 灯箱 Lightbox */
.lightbox-overlay {
    position: fixed;
    top: 0; left: 0; width: 100%; height: 100%;
    background: rgba(255, 255, 255, 0.96);
    backdrop-filter: blur(15px);
    z-index: 9999;
    display: flex;
    justify-content: center;
    align-items: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
}

.lightbox-overlay.active {
    opacity: 1;
    pointer-events: auto;
}

.lightbox-img {
    max-width: 88vw;
    max-height: 88vh;
    object-fit: contain;
    border-radius: 16px;
    box-shadow: var(--shadow-pop);
    transform: scale(0.96);
    transition: transform 0.3s cubic-bezier(0.165, 0.84, 0.44, 1);
}

.lightbox-overlay.active .lightbox-img {
    transform: scale(1);
}

.lightbox-close {
    position: absolute;
    top: 24px;
    right: 32px;
    color: var(--text-dark);
    font-size: 2.2rem;
    cursor: pointer;
    line-height: 1;
    transition: transform 0.2s;
}

.lightbox-close:hover {
    transform: rotate(90deg);
}

/* 4. 页脚 Footer */
.site-footer {
    background: var(--bg-warm);
    padding: 70px 0 40px;
    margin-top: 80px;
    border-top: 1px solid var(--border-light);
}

.footer-grid {
    display: grid;
    grid-template-columns: 1.8fr 1.2fr 1.2fr 1.2fr;
    gap: 40px;
    margin-bottom: 50px;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 10px;
}

.footer-links a {
    color: var(--text-gray);
    font-size: 0.92rem;
}

.footer-links a:hover {
    color: var(--text-dark);
}

/* 移动端响应式 */
@media (max-width: 850px) {
    .nav-links {
        position: fixed;
        top: 76px;
        left: 0;
        width: 100%;
        background: rgba(255, 255, 255, 0.98);
        backdrop-filter: blur(20px);
        -webkit-backdrop-filter: blur(20px);
        flex-direction: column;
        padding: 24px 32px;
        gap: 16px;
        align-items: flex-start;
        box-shadow: 0 12px 30px rgba(0, 0, 0, 0.08);
        display: none;
    }
    .nav-links.active {
        display: flex;
    }
    .mobile-menu-btn {
        display: block;
    }
    .nav-item-dropdown {
        flex-direction: column;
        align-items: flex-start;
        width: 100%;
    }
    .dropdown-menu {
        position: static;
        transform: none;
        box-shadow: none;
        border: none;
        opacity: 1;
        visibility: visible;
        pointer-events: auto;
        padding-left: 16px;
        background: transparent;
        min-width: unset;
        width: 100%;
        display: flex;
        flex-direction: column;
        gap: 6px;
    }
    .dropdown-chevron {
        display: none;
    }
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }
}