:root {
    --primary-deep: #0f172a;   /* Deep Tech Dark Navy */
    --primary-blue: #2563eb;   /* Rich Flat Royal Blue */
    --primary-light: #eff6ff;  /* Clean Ice Blue Light Tint */
    --accent-cyan: #06b6d4;    /* Vibrant Cyan for highlights */
    --text-dark: #1e293b;      /* Slate 800 for solid headings */
    --text-muted: #64748b;     /* Slate 500 for crisp body copy */
    --border-color: #e2e8f0;   /* Light gray borders for flat separation */
    --transition: all 0.25s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    -webkit-font-smoothing: antialiased;
}

body {
    background-color: #ffffff;
    color: var(--text-dark);
    overflow-x: hidden;
    line-height: 1.6;
}

/* Container helper */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* ------------------ NAVIGATION (Randomized Elegant Design) ------------------ */
nav {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: #ffffff;
    border-bottom: 2px solid var(--border-color);
    z-index: 1000;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 80px;
}

.logo-area {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    color: var(--primary-deep);
    font-weight: 700;
    font-size: 1.4rem;
    letter-spacing: -0.5px;
}

.logo-icon {
    width: 32px;
    height: 32px;
    background: var(--primary-blue);
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
}

/* Creative Non-standard Nav Layout */
.nav-links {
    display: flex;
    gap: 3rem;
    list-style: none;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    font-size: 0.95rem;
    transition: var(--transition);
}

.nav-links a:hover {
    color: var(--primary-blue);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.btn-text {
    text-decoration: none;
    color: var(--text-muted);
    font-weight: 500;
    font-size: 0.95rem;
    transition: var(--transition);
}

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

.btn-flat-nav {
    padding: 0.6rem 1.3rem;
    background: var(--primary-blue);
    color: white;
    text-decoration: none;
    font-weight: 500;
    font-size: 0.9rem;
    border-radius: 4px;
    transition: var(--transition);
}

.btn-flat-nav:hover {
    background: #1d4ed8;
}

/* Menu Toggle (Mobile Only) */
.menu-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    color: var(--text-dark);
}

/* Mobile Overlay Menu */
.mobile-menu {
    position: fixed;
    top: 80px;
    left: 0;
    width: 100%;
    height: calc(100vh - 80px);
    background: #ffffff;
    z-index: 999;
    display: flex;
    flex-direction: column;
    padding: 2rem;
    gap: 2rem;
    transform: translateX(100%);
    transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    border-top: 1px solid var(--border-color);
}

.mobile-menu.active {
    transform: translateX(0);
}

.mobile-menu a {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--text-dark);
    text-decoration: none;
}

/* ------------------ HERO SECTION ------------------ */
.hero {
    padding-top: 160px;
    padding-bottom: 80px;
    background: var(--primary-light);
    border-bottom: 2px solid var(--border-color);
}

.hero-grid {
    display: grid;
    grid-template-columns: 1.1fr 0.9fr;
    gap: 4rem;
    align-items: center;
}

.hero-content h1 {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.15;
    color: var(--primary-deep);
    margin-bottom: 1.5rem;
    letter-spacing: -1.5px;
}

.hero-content h1 span {
    color: var(--primary-blue);
}

.hero-content p {
    font-size: 1.2rem;
    color: var(--text-muted);
    margin-bottom: 2.5rem;
    max-width: 540px;
}

.hero-actions {
    display: flex;
    gap: 1rem;
}

.btn-primary {
    padding: 0.9rem 2rem;
    background: var(--primary-blue);
    color: white;
    border: none;
    border-radius: 4px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: var(--transition);
}

.btn-primary:hover {
    background: #1d4ed8;
}

.btn-secondary {
    padding: 0.9rem 2rem;
    background: #ffffff;
    color: var(--text-dark);
    border: 2px solid var(--border-color);
    border-radius: 4px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

.btn-secondary:hover {
    background: var(--primary-light);
    border-color: var(--primary-blue);
}

/* Flat tech graphic container */
.hero-graphic {
    background: #ffffff;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    padding: 2rem;
    box-shadow: 8px 8px 0px 0px rgba(37,99,235,0.1);
}

.graphic-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 1rem;
    margin-bottom: 1.5rem;
}

.graphic-title {
    font-weight: 700;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--primary-blue);
}

.pulse-bar {
    display: flex;
    align-items: flex-end;
    gap: 6px;
    height: 120px;
    margin-top: 1rem;
}

.bar {
    flex: 1;
    background: var(--primary-blue);
    border-radius: 2px 2px 0 0;
    min-height: 20px;
}

.bar.accent {
    background: var(--accent-cyan);
}

/* ------------------ DATA AUDIENCE SCALING (人群量级化) ------------------ */
.section-scale {
    padding: 80px 0;
    border-bottom: 2px solid var(--border-color);
    background: #ffffff;
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.section-tag {
    color: var(--primary-blue);
    font-weight: 700;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 2px;
    margin-bottom: 0.5rem;
    display: block;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--primary-deep);
    letter-spacing: -1px;
}

.scale-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 2rem;
}

.scale-card {
    background: var(--primary-light);
    border: 2px solid var(--border-color);
    padding: 2rem 1.5rem;
    border-radius: 6px;
    text-align: center;
    transition: var(--transition);
}

.scale-card:hover {
    border-color: var(--primary-blue);
    background: #ffffff;
    transform: translateY(-4px);
}

.scale-number {
    font-size: 2.8rem;
    font-weight: 900;
    color: var(--primary-blue);
    line-height: 1;
    margin-bottom: 0.5rem;
}

.scale-label {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--primary-deep);
    margin-bottom: 0.5rem;
}

.scale-desc {
    font-size: 0.9rem;
    color: var(--text-muted);
}

/* ------------------ PRODUCT PROFILE (广告产品) ------------------ */
.section-products {
    padding: 80px 0;
    background: #ffffff;
    border-bottom: 2px solid var(--border-color);
}

.product-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2.5rem;
}

.product-card {
    border: 2px solid var(--border-color);
    border-radius: 8px;
    padding: 2.5rem 2rem;
    background: #ffffff;
    display: flex;
    flex-direction: column;
    gap: 1.2rem;
    position: relative;
}

.product-card.featured {
    border-color: var(--primary-blue);
}

.badge-flat {
    position: absolute;
    top: -14px;
    right: 20px;
    background: var(--primary-blue);
    color: white;
    font-size: 0.75rem;
    font-weight: 700;
    padding: 4px 10px;
    border-radius: 4px;
    text-transform: uppercase;
}

.product-icon {
    width: 48px;
    height: 48px;
    background: var(--primary-light);
    color: var(--primary-blue);
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.product-card.featured .product-icon {
    background: var(--primary-blue);
    color: white;
}

.product-title {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--primary-deep);
}

.product-desc {
    font-size: 0.95rem;
    color: var(--text-muted);
    flex-grow: 1;
}

.product-features {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.6rem;
    border-top: 1px solid var(--border-color);
    padding-top: 1.2rem;
}

.product-features li {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
    color: var(--text-dark);
}

.product-features li i {
    color: var(--primary-blue);
    width: 16px;
    height: 16px;
}

/* ------------------ DELIVERY METHODS (投放方式) ------------------ */
.section-delivery {
    padding: 80px 0;
    background: var(--primary-light);
    border-bottom: 2px solid var(--border-color);
}

.delivery-row {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 4rem;
    align-items: center;
    margin-bottom: 5rem;
}

.delivery-row:last-child {
    margin-bottom: 0;
}

.delivery-row.reverse .delivery-content {
    grid-column: 2;
}
.delivery-row.reverse .delivery-visual {
    grid-column: 1;
    grid-row: 1;
}

.delivery-content h3 {
    font-size: 2rem;
    font-weight: 800;
    color: var(--primary-deep);
    margin-bottom: 1rem;
    letter-spacing: -0.5px;
}

.delivery-content p {
    color: var(--text-muted);
    font-size: 1.05rem;
    margin-bottom: 1.5rem;
}

.delivery-visual {
    background: #ffffff;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    padding: 2rem;
}

/* Mock programmatic UI */
.mock-ui-line {
    height: 12px;
    background: var(--border-color);
    border-radius: 4px;
    margin-bottom: 1rem;
    width: 100%;
}
.mock-ui-line.short { width: 60%; }
.mock-ui-line.medium { width: 85%; }
.mock-ui-accent {
    height: 36px;
    background: var(--primary-light);
    border-left: 4px solid var(--primary-blue);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    padding-left: 1rem;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--primary-blue);
}

/* ------------------ FOOTER ------------------ */
footer {
    background: var(--primary-deep);
    color: #ffffff;
    padding: 50px 0;
}

.footer-grid {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 2rem;
}

.footer-logo {
    font-weight: 700;
    font-size: 1.3rem;
    letter-spacing: -0.5px;
}

.footer-links {
    display: flex;
    gap: 2rem;
    list-style: none;
}

.footer-links a {
    color: #94a3b8;
    text-decoration: none;
    font-size: 0.9rem;
    transition: var(--transition);
}

.footer-links a:hover {
    color: #ffffff;
}

.copyright {
    color: #64748b;
    font-size: 0.85rem;
    width: 100%;
    border-top: 1px solid #334155;
    padding-top: 2px;
    margin-top: 2px;
    text-align: center;
}

/* ------------------ RESPONSIVE BREAKPOINTS ------------------ */
@media (max-width: 1024px) {
    .scale-grid { grid-template-columns: repeat(2, 1fr); }
    .product-grid { grid-template-columns: repeat(2, 1fr); }
    .hero-grid { gap: 2rem; }
    .hero-content h1 { font-size: 2.8rem; }
}

@media (max-width: 768px) {
    .nav-links, .nav-actions .btn-text, .nav-actions .btn-flat-nav { display: none; }
    .menu-toggle { display: block; }
    .hero-grid { grid-template-columns: 1fr; }
    .hero-graphic { order: -1; }
    .delivery-row { grid-template-columns: 1fr; gap: 2rem; }
    .delivery-row.reverse .delivery-content { grid-column: 1; }
    .delivery-row.reverse .delivery-visual { grid-column: 1; }
    .product-grid { grid-template-columns: 1fr; }
    .scale-grid { grid-template-columns: 1fr; }
    .hero-content h1 { font-size: 2.4rem; }
}