/* --- Reset & Base --- */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    /* Color Tokens (HSL) - Knowledge Infrastructure Theme */
    --bg-dark: #1C1C1E;                     /* Charcoal */
    --bg-nav: rgba(28, 28, 30, 0.85);
    --bg-surface: #28282A;                  /* Slightly lighter charcoal */
    --bg-surface-glass: rgba(40, 40, 42, 0.7);
    --border-color: rgba(245, 240, 235, 0.1);
    --border-glow: rgba(217, 119, 6, 0.2);
    
    --primary: #D97706;                     /* Amber Orange */
    --primary-glow: rgba(217, 119, 6, 0.4);
    --secondary: #D97706;                   /* Fog Blue */
    --secondary-glow: rgba(107, 123, 141, 0.35);
    
    --text-primary: #F5F0EB;                /* Warm White / Beige */
    --text-secondary: #B0B3B8;              /* Soft Gray */
    --text-muted: #7E8287;
    
    /* Typography */
    --font-heading: "Microsoft YaHei", "微软雅黑", "Noto Sans SC", sans-serif;
    --font-body: "Microsoft YaHei", "微软雅黑", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    
    /* Layout Constants */
    --nav-height: 80px;
    --container-width: 1200px;
    
    /* System Shadows & Borders */
    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --transition-smooth: all 0.35s cubic-bezier(0.25, 0.8, 0.25, 1);
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: var(--nav-height);
}

body {
    background-color: var(--bg-dark);
    color: var(--text-primary);
    font-family: var(--font-body);
    font-size: 16px;
    line-height: 1.6;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

/* --- Typographical System --- */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 700;
    line-height: 1.25;
    color: var(--text-primary);
}

h1 {
    font-size: clamp(2rem, 4vw, 2.6rem);
    letter-spacing: -0.015em;
}

h2 {
    font-size: clamp(1.6rem, 3.2vw, 2rem);
    letter-spacing: -0.01em;
}

h3 {
    font-size: clamp(1.25rem, 2.4vw, 1.5rem);
}

p {
    color: var(--text-secondary);
    font-weight: 400;
}

a {
    color: var(--primary);
    text-decoration: none;
    transition: var(--transition-smooth);
}

a:hover {
    color: var(--text-primary);
}

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

/* --- Layout Utility --- */
.container {
    width: 100%;
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 24px;
}

.section-padding {
    padding: 20px 0;
}

@media (max-width: 768px) {
    .section-padding {
        padding: 60px 0;
    }
}

.text-center {
    text-align: center;
}

.flex-center {
    display: flex;
    justify-content: center;
    align-items: center;
}

/* --- Premium Buttons & Interactivity --- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 28px;
    font-family: var(--font-heading);
    font-size: 15px;
    font-weight: 600;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition-smooth);
    border: 1px solid transparent;
    position: relative;
    overflow: hidden;
}

.btn-primary {
    background-color: var(--primary);
    color: #1C1C1E;
    box-shadow: 0 4px 20px var(--primary-glow);
}

.btn-primary:hover {
    background-color: #F59E0B; /* Lighter Amber for hover */
    box-shadow: 0 6px 24px var(--primary-glow);
    transform: translateY(-2px);
    color: #1C1C1E;
}

.btn-secondary {
    background-color: transparent;
    border: 1px solid var(--primary);
    color: var(--primary);
}

.btn-secondary:hover {
    background-color: var(--primary-glow);
    transform: translateY(-2px);
    color: var(--primary);
}

.btn-accent {
    background-color: var(--secondary);
    color: #F5F0EB;
    box-shadow: 0 4px 20px var(--secondary-glow);
}

.btn-accent:hover {
    background-color: #8C9BAB; /* Lighter fog blue for hover */
    box-shadow: 0 6px 24px var(--secondary-glow);
    transform: translateY(-2px);
    color: #F5F0EB;
}

.btn-link {
    padding: 0;
    background: transparent;
    border: none;
    color: var(--primary);
    font-weight: 600;
    cursor: pointer;
    font-family: var(--font-heading);
    display: inline-flex;
    align-items: center;
    gap: 6px;
}

.btn-link::after {
    content: '→';
    transition: var(--transition-smooth);
}

.btn-link:hover::after {
    transform: translateX(4px);
}

/* Glassmorphism Cards */
.card {
    background: var(--bg-surface-glass);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    padding: 32px;
    transition: var(--transition-smooth);
}

.card:hover {
    border-color: var(--primary-glow);
    box-shadow: 0 10px 30px rgba(217, 119, 6, 0.08);
    transform: translateY(-4px);
}

/* --- Form Elements --- */
.form-group {
    margin-bottom: 24px;
}

.form-group label {
    display: block;
    font-family: var(--font-heading);
    font-size: 14px;
    font-weight: 500;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.form-control {
    width: 100%;
    padding: 14px 16px;
    background-color: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-family: var(--font-body);
    font-size: 15px;
    transition: var(--transition-smooth);
}

.form-control:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 10px rgba(217, 119, 6, 0.15);
}

.form-control::placeholder {
    color: var(--text-muted);
}

select.form-control {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%23f3f4f6' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 16px center;
    background-size: 18px;
    padding-right: 40px;
}

/* --- Global Navbar --- */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: var(--nav-height);
    background-color: transparent;
    border-bottom: 1px solid transparent;
    z-index: 1000;
    transition: var(--transition-smooth);
}

.navbar.scrolled {
    background-color: var(--bg-nav);
    border-bottom: 1px solid var(--border-color);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
}

.navbar .container {
    height: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-family: var(--font-heading);
    font-size: 24px;
    font-weight: 800;
    letter-spacing: -0.01em;
    color: var(--text-primary);
}

.logo img {
    height: 60px;
    width: auto;
    display: block;
    object-fit: contain;
}

.logo-glow {
    color: var(--primary);
    text-shadow: 0 0 10px var(--primary-glow);
}

.nav-links {
    display: flex;
    gap: 12px;
    list-style: none;
}

.nav-links a {
    color: var(--text-secondary);
    font-family: var(--font-heading);
    font-weight: 500;
    font-size: 14px;
    position: relative;
    padding: 6px 0;
}

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

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary);
    transition: var(--transition-smooth);
}

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

.nav-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

/* Mobile Nav Toggle */
.hamburger {
    display: none;
    flex-direction: column;
    justify-content: space-between;
    width: 24px;
    height: 18px;
    background: transparent;
    border: none;
    cursor: pointer;
    z-index: 1100;
}

.hamburger span {
    width: 100%;
    height: 2px;
    background-color: var(--text-primary);
    transition: var(--transition-smooth);
}

/* Mobile Nav Drawer */
@media (max-width: 992px) {
    .nav-links {
        position: fixed;
        top: 0;
        right: -100%;
        width: 300px;
        height: 100vh;
        background-color: var(--bg-surface);
        flex-direction: column;
        justify-content: flex-start;
        align-items: center;
        gap: 20px;
        padding: 100px 24px 40px 24px;
        overflow-y: auto;
        z-index: 1050;
        transition: var(--transition-smooth);
        border-left: 1px solid var(--border-color);
        box-shadow: -10px 0 30px rgba(0, 0, 0, 0.5);
    }
    
    .nav-links.active {
        right: 0;
    }
    
    .nav-actions {
        display: none; /* In mobile drawer instead */
    }
    
    .hamburger {
        display: flex;
    }
    
    .hamburger.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .hamburger.active span:nth-child(2) {
        opacity: 0;
    }
    
    .hamburger.active span:nth-child(3) {
        transform: rotate(-45deg) translate(6px, -7px);
    }
}

/* --- Global Footer --- */
.footer {
    background-color: var(--bg-surface);
    border-top: 1px solid var(--border-color);
    padding: 80px 0 30px 0;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 2fr;
    gap: 48px;
    margin-bottom: 60px;
}

@media (max-width: 992px) {
    .footer-grid {
        grid-template-columns: 1fr 1fr;
        gap: 32px;
    }
}

@media (max-width: 576px) {
    .footer-grid {
        grid-template-columns: 1fr;
    }
}

.footer-col h4 {
    font-size: 16px;
    margin-bottom: 24px;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--text-primary);
}

.footer-col p {
    font-size: 14px;
    margin-bottom: 20px;
}

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

.footer-links li {
    margin-bottom: 12px;
}

.footer-links a {
    color: var(--text-secondary);
    font-size: 14px;
}

.footer-links a:hover {
    color: var(--primary);
    padding-left: 4px;
}

.social-links {
    display: flex;
    gap: 16px;
    margin-top: 20px;
}

.social-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background-color: var(--bg-dark);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    transition: var(--transition-smooth);
}

.social-icon:hover {
    background-color: var(--primary);
    color: #1C1C1E;
    transform: translateY(-2px);
}

.newsletter-form {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.newsletter-form .form-control {
    font-size: 14px;
    padding: 10px 14px;
    width: 100%;
    box-sizing: border-box;
}

.newsletter-form .btn {
    padding: 10px 20px;
    align-self: flex-start;
}

.reason-label {
    font-size: 13px;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 2px;
}

.reason-group {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

.reason-option {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    font-size: 12px;
    color: var(--text-secondary);
    background: var(--bg-dark);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    padding: 5px 12px;
    cursor: pointer;
    transition: var(--transition-smooth);
}

.reason-option:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.reason-option input[type="checkbox"] {
    display: none;
}

.reason-option:has(input:checked) {
    background: rgba(217, 119, 6, 0.15);
    border-color: var(--primary);
    color: var(--primary);
}

.reason-hint-inline {
    font-size: 11px;
    font-weight: 400;
    color: var(--text-muted);
}

.footer-bottom {
    border-top: 1px solid var(--border-color);
    padding-top: 30px;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
}

.footer-bottom p {
    font-size: 13px;
    color: var(--text-muted);
}

.footer-legal {
    display: flex;
    gap: 24px;
}

.footer-legal a {
    color: var(--text-muted);
    font-size: 13px;
}

.footer-legal a:hover {
    color: var(--primary);
}

/* --- Interactive Placeholders & UI Elements --- */
.image-placeholder {
    width: 100%;
    height: 100%;
    min-height: 300px;
    background: linear-gradient(135deg, var(--bg-surface), var(--bg-dark));
    border: 1px dashed var(--text-muted);
    border-radius: var(--radius-lg);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    color: var(--text-muted);
    font-family: var(--font-heading);
    font-weight: 500;
    gap: 12px;
}

.image-placeholder svg {
    width: 48px;
    height: 48px;
    stroke: var(--text-muted);
}

.image-placeholder-inner {
    border: 1px solid var(--border-color);
    padding: 16px;
    border-radius: var(--radius-md);
    background: var(--bg-surface-glass);
    text-align: center;
}

/* --- Scroll Animations --- */
.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s ease, transform 0.8s ease;
}

.reveal.active {
    opacity: 1;
    transform: translateY(0);
}

/* --- Header Banner Ticker --- */
.trust-ticker {
    background-color: var(--bg-surface);
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
    padding: 16px 0;
    overflow: hidden;
    white-space: nowrap;
    position: relative;
}

.ticker-track {
    display: inline-flex;
    animation: ticker 25s linear infinite;
    gap: 60px;
    padding-right: 60px;
}

.ticker-item {
    font-family: var(--font-heading);
    font-weight: 600;
    font-size: 14px;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 12px;
    letter-spacing: 0.05em;
    text-transform: uppercase;
}

.ticker-item::before {
    content: '';
    display: block;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background-color: var(--primary);
    box-shadow: 0 0 8px var(--primary);
}

@keyframes ticker {
    0% {
        transform: translate3d(0, 0, 0);
    }
    100% {
        transform: translate3d(-50%, 0, 0);
    }
}

/* --- Global Hero Styles matching Homepage --- */
.hero-tag {
    display: inline-block;
    padding: 6px 14px;
    background-color: rgba(217, 119, 6, 0.08) !important;
    border: 1px solid var(--border-glow) !important;
    color: var(--primary) !important;
    border-radius: 100px;
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 24px;
    font-family: var(--font-heading);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.aicso-hero, .research-hero, .courses-hero, .enterprise-hero, .daily-hero, .news-hero, .about-hero, .download-hero {
    background: radial-gradient(circle at center, rgba(217, 119, 6, 0.04) 0%, transparent 70%) !important;
}

.aicso-hero h1, .research-hero h1, .courses-hero h1, .enterprise-hero h1, .daily-hero h1, .news-hero h1, .about-hero h1, .download-hero h1 {
    background: linear-gradient(90deg, var(--text-primary) 30%, var(--primary) 70%) !important;
    -webkit-background-clip: text !important;
    -webkit-text-fill-color: transparent !important;
    display: block !important;
    width: fit-content !important;
    margin: 0 auto 16px auto !important;
}

/* --- Global Subpage Hero Subtitle Wrapping Control --- */
.aicso-hero p, .research-hero p, .courses-hero p, .enterprise-hero p, .daily-hero p, .news-hero p, .about-hero p, .download-hero p {
    white-space: nowrap !important;
    width: max-content !important;
    max-width: 100% !important;
    margin-left: auto !important;
    margin-right: auto !important;
}

@media (max-width: 992px) {
    .aicso-hero p, .research-hero p, .courses-hero p, .enterprise-hero p, .daily-hero p, .news-hero p, .about-hero p, .download-hero p {
        white-space: normal !important;
        width: auto !important;
    }
}