:root {
    /* Color System - Premium & Commercial (Optimized) */
    --sm-black: #1B1B1B;      /* Primary Text / Headings */
    --sm-dark-gray: #333333;  /* Body Text */
    --sm-gray-text: #888888;  /* Secondary Text */
    --sm-light-gray: #D3D4D4; /* Meta Text */
    --sm-border: #E5E5E5;     /* Borders */
    --sm-bg-light: #F7F8FA;   /* Section Background */
    --sm-white: #FFFFFF;      
    
    --sm-yellow: #FCBB1A;     /* Brand Color - Warmer, Premium */
    --sm-yellow-hover: #E0A615;
    
    /* Spacing & Layout */
    --sm-container-width: 1200px;
    --sm-header-height: 80px;
    --sm-section-padding: 100px;
    
    /* Typography */
    /* English/Numbers: Barlow Condensed (Similar to Akrobat), Fallback to Oswald/Arial */
    /* Chinese: Noto Sans SC (Source Han Sans), Fallback to PingFang */
    --font-main: "Barlow Condensed", "Oswald", "Helvetica Neue", Helvetica, Arial, "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    --font-cn: "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

/* 
   ==========================================================================
   Global Reset & Base Styles
   ========================================================================== 
*/
body {
    font-family: var(--font-main);
    color: var(--sm-dark-gray);
    background-color: var(--sm-white);
    font-size: 16px;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

a {
    color: var(--sm-black);
    text-decoration: none;
    transition: color 0.3s ease;
}

a:hover {
    color: var(--sm-yellow-hover);
}

/* Typography Levels */
h1, h2, h3, h4, h5, h6, .h1, .h2, .h3, .h4, .h5, .h6 {
    color: var(--sm-black);
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1rem;
}

.display-1 { font-size: 64px; font-weight: 700; } /* Hero Title */
.display-2 { font-size: 56px; font-weight: 700; }
.display-3 { font-size: 48px; font-weight: 700; } /* Page Title */
.display-4 { font-size: 36px; font-weight: 700; } /* Section Title */
.display-5 { font-size: 28px; font-weight: 700; }
.display-6 { font-size: 24px; font-weight: 600; } /* Card Title */

p.lead {
    font-size: 18px;
    font-weight: 400;
    color: var(--sm-gray-text);
    line-height: 1.6;
}

.text-muted { color: var(--sm-gray-text) !important; }
.text-brand { color: var(--sm-yellow) !important; }

/* Global Border Radius Reset (Square/Sharp) */
.btn, .card, .form-control, .modal-content, .dropdown-menu, .nav-pills .nav-link, .badge {
    border-radius: 0 !important;
}

.rounded-0 { border-radius: 0 !important; }
.rounded-circle { border-radius: 50% !important; } /* Keep avatars round */

/* 
   ==========================================================================
   Layout & Sections
   ========================================================================== 
*/
section {
    padding: var(--sm-section-padding) 0;
}

@media (max-width: 768px) {
    :root {
        --sm-section-padding: 60px;
    }
    .display-1 { font-size: 48px; }
    .display-3 { font-size: 36px; }
    .display-4 { font-size: 28px; }
}

/* Mobile 优化：iPhone16 393×852 */
@media (max-width: 480px) {
    :root { --sm-section-padding: 48px; }
    body { font-size: 16px; }
    .nav-link { margin: 0 8px; padding: 14px 0 !important; min-height: 44px; min-width: 44px; display: inline-flex; align-items: center; justify-content: center; }
    .navbar-brand img { height: 28px; }
    .btn { min-height: 44px; min-width: 44px; padding: 12px 16px; font-size: 16px; }
    .btn-lg { padding: 14px 24px; font-size: 16px; }
    .btn-sm { min-height: 40px; }
    .form-control { min-height: 44px; font-size: 16px; }
    .pagination .page-link { min-width: 44px; min-height: 44px; }
    .display-1 { font-size: 40px; }
    .display-3 { font-size: 28px; }
    .display-4 { font-size: 24px; }
    p.lead { font-size: 16px; }
    .container { padding-left: 16px; padding-right: 16px; }
    .card-body { padding: 24px; }
    .v2-page-header { padding-top: 120px; padding-bottom: 60px; }
    .hero-section { height: auto; min-height: 0; padding-top: 120px; padding-bottom: 32px; }
    .hero-bg-video { opacity: 0.45; }
    .hero-content .display-1 { font-size: 34px; }
    .hero-content .btn { width: 100%; max-width: 240px; }
    .hero-section .col-md-3 { flex: 0 0 50%; max-width: 50%; margin-bottom: 12px; }
    .service-image { height: 200px; }
    .product-illus { height: 200px; }
    .service-item { border: none !important; }
    #strategy .service-image,
    #measurement .service-image,
    #design .service-image { margin-top: 16px; }
    #research .bg-light[style*="background-image"],
    #organization .bg-light[style*="background-image"] { margin-top: 16px; }
    .footer-v2 { padding: 48px 0 24px; }
    .footer-v2, .copyright, .text-white-50 { font-size: 14px !important; }
    .footer-link { min-height: 44px; line-height: 44px; }
    .p-5 { padding: 1rem !important; }
    .mb-5 { margin-bottom: 1.5rem !important; }
    .pb-5 { padding-bottom: 1.5rem !important; }
    .btn-contact { display: none; }
}

/* Container Override */
@media (min-width: 1400px) {
    .container { max-width: var(--sm-container-width); }
}

/* 
   ==========================================================================
   Components
   ========================================================================== 
*/

/* Buttons */
.btn {
    padding: 12px 36px;
    font-weight: 600;
    font-size: 16px;
    letter-spacing: 0.5px;
    transition: all 0.3s ease;
    border-width: 1px;
}

.btn-lg {
    padding: 16px 48px;
    font-size: 18px;
}

.btn-sm {
    padding: 8px 24px;
    font-size: 14px;
}

.btn-brand {
    background-color: var(--sm-yellow);
    border-color: var(--sm-yellow);
    color: var(--sm-black);
}

.btn-brand:hover {
    background-color: var(--sm-yellow-hover);
    border-color: var(--sm-yellow-hover);
    color: var(--sm-black);
}

.btn-dark {
    background-color: var(--sm-black);
    border-color: var(--sm-black);
    color: #fff;
}

.btn-dark:hover {
    background-color: #000;
    border-color: #000;
}

.btn-outline-dark {
    border-color: var(--sm-black);
    color: var(--sm-black);
    background: transparent;
}

.btn-outline-dark:hover {
    background-color: var(--sm-black);
    color: #fff;
}

.btn-outline-light {
    border-color: #fff;
    color: #fff;
    background: transparent;
}

.btn-outline-light:hover {
    background-color: #fff;
    color: var(--sm-black);
}

/* Cards */
.card {
    border: none;
    background: #fff;
    transition: all 0.3s ease;
}

.card-body {
    padding: 40px;
}

.shadow-sm {
    box-shadow: 0 4px 20px rgba(0,0,0,0.04) !important;
}

.card:hover.shadow-sm {
    box-shadow: 0 10px 30px rgba(0,0,0,0.08) !important;
    transform: translateY(-5px);
}

/* Forms */
.form-control {
    height: 56px;
    border: 1px solid var(--sm-border);
    padding: 0 20px;
    background-color: #fff;
    color: var(--sm-black);
}

.form-control:focus {
    border-color: var(--sm-black);
    box-shadow: none;
    background-color: #fff;
}

/* 
   ==========================================================================
   Navbar (Dual State)
   ========================================================================== 
*/
.navbar {
    padding: 0;
    height: var(--sm-header-height);
    transition: all 0.3s ease;
}

.navbar-brand img {
    height: 32px; /* Slightly smaller for elegance */
    width: auto;
}

.nav-link {
    font-weight: 500;
    font-size: 15px;
    margin: 0 18px;
    padding: 28px 0 !important; /* Center vertically in 80px header */
    position: relative;
    letter-spacing: 0.5px;
}

/* Transparent State */
.navbar-transparent {
    background-color: transparent;
    border-bottom: 1px solid rgba(255,255,255,0.1);
}

.navbar-transparent .nav-link {
    color: rgba(255,255,255,0.9);
}

.navbar-transparent .nav-link:hover,
.navbar-transparent .nav-link.active {
    color: #fff;
}

/* Scrolled State */
.navbar-scrolled {
    background-color: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(20px);
    box-shadow: 0 1px 0 rgba(0,0,0,0.05);
}

.navbar-scrolled .nav-link {
    color: var(--sm-black);
}

.navbar-scrolled .nav-link:hover,
.navbar-scrolled .nav-link.active {
    color: var(--sm-yellow-hover); /* Use brand color for active state in light mode */
}

/* Active Indicator Line */
.nav-link::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: 20px;
    left: 0;
    background-color: var(--sm-yellow);
    transition: width 0.3s ease;
}

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

/* Logo Filter */
.logo-white { filter: brightness(0) invert(1); }
.navbar-scrolled .logo-white { filter: none; }
.navbar-transparent .btn-contact { color: #fff; }
.navbar-transparent .btn-contact:hover { color: #fff; }
.navbar-scrolled .btn-contact { color: var(--sm-black); }

.navbar-custom .navbar-toggler { border-color: rgba(255,255,255,0.6); }
.navbar-scrolled .navbar-toggler { border-color: rgba(0,0,0,0.3); }
.navbar-custom .navbar-toggler-icon {
    width: 1.25em;
    height: 1.25em;
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba(255, 255, 255, 0.85)' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e");
}
.navbar-scrolled .navbar-toggler-icon {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba(0, 0, 0, 0.85)' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e");
}

/* 
   ==========================================================================
   Hero Section
   ========================================================================== 
*/
.hero-section {
    height: 100vh;
    min-height: 600px;
    background-color: #000;
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.hero-bg-video {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    z-index: 0;
    opacity: 0.6; /* Darken slightly more for text readability */
}

.hero-content {
    position: relative;
    z-index: 2;
    text-align: center;
    color: #fff;
    max-width: 900px;
    padding: 0 20px;
}

/* 
   ==========================================================================
   Page Headers (For Subpages)
   ========================================================================== 
*/
.v2-page-header {
    padding-top: 180px; /* Account for fixed navbar */
    padding-bottom: 100px;
    background-color: #111;
}

.v2-page-header.has-banner {
    padding-bottom: 0;
    overflow: hidden;
}

.v2-page-header.has-banner > .w-100 {
    display: block;
    margin: 0;
}

/* 
   ==========================================================================
   Utilities & Helpers
   ========================================================================== 
*/
.bg-light { background-color: var(--sm-bg-light) !important; }
.bg-black { background-color: #000 !important; }

.ls-1 { letter-spacing: 1px; }
.ls-2 { letter-spacing: 2px; }

.fw-900 { font-weight: 700; } /* Re-map 900 to 700 for restraint */

/* Case Detail Content Width */
.v2-case-content .container {
    max-width: 1280px;
}

.v2-case-content .article-content {
    max-width: 100%;
    margin: 0 auto;
}

.v2-case-content .article-content img,
.v2-case-content .article-content video,
.v2-case-content .article-content iframe,
.v2-case-content .article-content table {
    max-width: 100%;
    height: auto;
}

/* Service imagery: enforce consistent 16:9 horizontal framing */
.service-image {
    width: 100%;
    height: 400px;
    object-fit: cover;
}

@media (max-width: 768px) {
    .service-image {
        height: 240px;
    }
}

.product-illus {
    height: 350px;
    background-color: transparent;
    background-size: contain;
    background-position: center;
    background-repeat: no-repeat;
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    border: none;
    box-shadow: none;
}

@media (max-width: 768px) {
    .product-illus { height: 260px; }
}

/* Image Zoom Effect */
.transition-zoom {
    transition: transform 0.6s ease;
}
.card:hover .transition-zoom {
    transform: scale(1.05);
}

/* Badges */
.badge {
    padding: 8px 12px;
    font-weight: 500;
    font-size: 12px;
    letter-spacing: 1px;
    text-transform: uppercase;
}

/* Footer */
.footer-v2 {
    background-color: var(--sm-black); /* Ensure dark background */
    color: #fff;
    padding: 80px 0 40px;
    font-size: 14px;
}

.footer-v2 h5 {
    color: #fff;
    font-size: 16px;
    font-weight: 700;
    margin-bottom: 24px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.footer-link {
    display: block;
    color: rgba(255,255,255,0.6);
    margin-bottom: 12px;
    transition: all 0.3s ease;
    text-decoration: none;
}

.footer-link:hover {
    color: var(--sm-yellow);
    transform: translateX(5px);
}

.footer-v2 p {
    color: rgba(255,255,255,0.5);
    line-height: 1.8;
}
.wechat-qr-code { display: none; }
.wechat-hover-container:hover .wechat-qr-code, .wechat-qr-code:hover { display: block !important; }

.copyright {
    margin-top: 60px;
    padding-top: 30px;
    border-top: 1px solid rgba(255,255,255,0.1);
    color: rgba(255,255,255,0.4);
    font-size: 12px;
}
/* Case Filter Bar */
.case-filter {
    min-height: 56px;
    display: flex;
    gap: 12px;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    scroll-snap-type: x mandatory;
}
.case-filter a {
    display: inline-flex;
    align-items: center;
    line-height: 1.2;
    padding: 8px 0;
    scroll-snap-align: start;
}

/* 触控优化：列表横向滑动体验 */
.horizontal-scroll {
    display: flex;
    gap: 12px;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    scroll-snap-type: x mandatory;
}
.horizontal-scroll > * { scroll-snap-align: start; }

/* Navbar Toggler 可点击区域 */
.navbar-toggler { min-width: 44px; min-height: 44px; padding: 8px 12px; }

/* Pagination (Visual Spec) */
.pagination {
    gap: 8px;
}
.pagination .page-link {
    padding: 8px 14px;
    border: 1px solid var(--sm-border);
    color: var(--sm-black);
    background-color: #fff;
}
.pagination .page-link:hover {
    border-color: var(--sm-black);
    color: var(--sm-black);
}
.pagination .page-item.active .page-link {
    background-color: var(--sm-black);
    border-color: var(--sm-black);
    color: #fff !important;
}
.pagination .page-item.disabled .page-link {
    color: var(--sm-gray-text);
    background-color: #fff;
    border-color: var(--sm-border);
    pointer-events: none;
}
.navbar-toggler[aria-expanded="true"] .navbar-toggler-icon {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba(255, 255, 255, 0.95)' stroke-linecap='round' stroke-width='2' d='M7 7 L23 23 M23 7 L7 23'/%3e%3c/svg%3e");
}
.navbar-scrolled .navbar-toggler[aria-expanded="true"] .navbar-toggler-icon {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba(0, 0, 0, 0.95)' stroke-linecap='round' stroke-width='2' d='M7 7 L23 23 M23 7 L7 23'/%3e%3c/svg%3e");
}

@media (max-width: 992px) {
    .offcanvas { background: rgba(0,0,0,0.94); backdrop-filter: blur(8px); }
    .offcanvas-header { border-bottom: 1px solid rgba(255,255,255,0.1); }
    .offcanvas .nav-link { color: #fff; font-size: 18px; padding: 12px 0 !important; margin: 0; }
    .offcanvas .nav-link:hover { color: var(--sm-yellow); }
    .offcanvas .btn-outline-light { border-color: rgba(255,255,255,0.5); }
}

/* Mobile 预览强制样式（无需改变窗口尺寸） */
body.mobile-preview-393 { font-size: 16px; }
body.mobile-preview-393 .nav-link { margin: 0 8px; padding: 14px 0 !important; min-height: 44px; min-width: 44px; display: inline-flex; align-items: center; justify-content: center; }
body.mobile-preview-393 .navbar-nav .nav-link,
body.mobile-preview-393 .nav-pills .nav-link { min-height: 44px !important; line-height: 44px !important; padding: 0 16px !important; min-width: 44px; display: inline-flex; align-items: center; justify-content: center; }
body.mobile-preview-393 .navbar-brand img { height: 28px; }
body.mobile-preview-393 .navbar-brand { min-height: 44px; display: inline-flex; align-items: center; }
body.mobile-preview-393 .btn { min-height: 44px; min-width: 44px; padding: 12px 16px; font-size: 16px; }
body.mobile-preview-393 .btn-link { min-height: 44px; padding: 12px 16px; display: inline-flex; align-items: center; justify-content: center; }
body.mobile-preview-393 .btn-lg { padding: 14px 24px; font-size: 16px; }
body.mobile-preview-393 .btn-sm { min-height: 40px; }
body.mobile-preview-393 .form-control { min-height: 44px; font-size: 16px; }
body.mobile-preview-393 .pagination .page-link { min-width: 44px; min-height: 44px; }
body.mobile-preview-393 .container { padding-left: 16px; padding-right: 16px; }
body.mobile-preview-393 .footer-v2 { padding: 48px 0 24px; }
body.mobile-preview-393 .footer-v2, body.mobile-preview-393 .copyright, body.mobile-preview-393 .text-white-50 { font-size: 14px !important; }
body.mobile-preview-393 .footer-link { display: inline-flex; align-items: center; min-height: 44px; line-height: 44px; padding: 10px 0; }
body.mobile-preview-393 .footer-v2 a.text-white.fs-4 { min-width: 44px; min-height: 44px; display: inline-flex; align-items: center; justify-content: center; }
body.mobile-preview-393 .copyright a { min-height: 44px; display: inline-flex; align-items: center; }
body.mobile-preview-393 .case-filter a { min-height: 44px; min-width: 44px; display: inline-flex; align-items: center; justify-content: center; }
body.mobile-preview-393 .hero-section { height: auto; min-height: 0; padding-top: 120px; padding-bottom: 32px; }
body.mobile-preview-393 .hero-content .display-1 { font-size: 34px; }
body.mobile-preview-393 .hero-content .btn { width: 100%; max-width: 240px; }
body.mobile-preview-393 .container { max-width: 393px; margin-left: auto; margin-right: auto; }
body.mobile-preview-393 .hero-section .col-md-3 { flex: 0 0 50%; max-width: 50%; margin-bottom: 12px; }
body.mobile-preview-393 .service-image { height: 200px; }
body.mobile-preview-393 .product-illus { height: 200px; }
body.mobile-preview-393 .service-item { border: none !important; }
body.mobile-preview-393 .d-lg-block { display: none !important; }
body.mobile-preview-393 .d-lg-none { display: block !important; }
body.mobile-preview-393 .services-section .bg-brand a { min-height: 44px; display: inline-flex; align-items: center; }
body.mobile-preview-393 .about-cta { flex-wrap: wrap; }
body.mobile-preview-393 .about-cta { max-width: 360px; margin-left: auto; margin-right: auto; }
body.mobile-preview-393 .about-cta .btn { width: 100%; max-width: 360px; }
body.mobile-preview-393 .home-cta { flex-wrap: wrap; }
body.mobile-preview-393 .home-cta { max-width: 360px; margin-left: auto; margin-right: auto; }
body.mobile-preview-393 .home-cta .btn { width: 100%; max-width: 360px; }

@media (max-width: 576px) {
    .about-cta { flex-wrap: wrap; }
    .about-cta .btn { width: 100%; }
    .home-cta { flex-wrap: wrap; }
    .home-cta .btn { width: 100%; }
}