/* ===========================================
   CDTSC Theme - Layout v2
   Header / Hero / Quick Links / Footer / Grid
   Optimized for premium academic feel
   =========================================== */

/* ---- Container ---- */
.cdtsc-container { width: 100%; max-width: 1200px; margin: 0 auto; padding: 0 var(--space-6); }
.cdtsc-container-wide { max-width: 1400px; margin: 0 auto; padding: 0 var(--space-6); }
.cdtsc-container-narrow { max-width: 800px; margin: 0 auto; padding: 0 var(--space-4); }

/* ---- Grid ---- */
.cdtsc-grid { display: grid; gap: var(--space-6); }
.cdtsc-grid-2 { grid-template-columns: repeat(2, 1fr); }
.cdtsc-grid-3 { grid-template-columns: repeat(3, 1fr); }
.cdtsc-grid-4 { grid-template-columns: repeat(4, 1fr); }

/* ---- Flex Helpers ---- */
.cdtsc-flex { display: flex; gap: var(--space-4); }
.cdtsc-flex-center { display: flex; align-items: center; justify-content: center; }
.cdtsc-flex-between { display: flex; align-items: center; justify-content: space-between; }
.cdtsc-flex-wrap { flex-wrap: wrap; }

/* ---- Section ---- */
.cdtsc-section { padding: var(--space-20) 0; }
.cdtsc-section-sm { padding: var(--space-4) 0; }
.cdtsc-section-light { background: var(--color-gray-50); }
.cdtsc-section-alt { background: var(--color-gray-75); }

.cdtsc-section-title { text-align: center; margin-bottom: var(--space-12); }
.cdtsc-section-title h2 {
    font-size: var(--text-3xl);
    font-weight: var(--fw-extrabold);
    color: var(--color-gray-900);
    margin-bottom: var(--space-3);
    letter-spacing: -0.02em;
    position: relative;
    display: inline-block;
}
.cdtsc-section-title h2::after {
    content: '';
    display: block;
    width: 48px;
    height: 3px;
    margin: var(--space-3) auto 0;
    background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
    border-radius: var(--radius-full);
}
.cdtsc-section-title p {
    font-size: var(--text-lg);
    color: var(--color-gray-500);
    max-width: 560px;
    margin: 0 auto;
    line-height: var(--leading-relaxed);
}

.cdtsc-section-link { text-align: center; margin-top: var(--space-12); }
.cdtsc-section-link a {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-6);
    font-weight: var(--fw-semibold);
    font-size: var(--text-sm);
    color: var(--color-primary);
    background: var(--color-white);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-full);
    transition: all var(--transition-base);
}
.cdtsc-section-link a:hover {
    color: var(--color-white);
    background: var(--color-primary);
    border-color: var(--color-primary);
    gap: var(--space-3);
    box-shadow: var(--shadow-md);
}
.cdtsc-section-link a::after { content: '\2192'; transition: transform var(--transition-base); }
.cdtsc-section-link a:hover::after { transform: translateX(2px); }

/* ============================================
   Header
   ============================================ */

.cdtsc-header {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: saturate(180%) blur(12px);
    -webkit-backdrop-filter: saturate(180%) blur(12px);
    border-bottom: 1px solid var(--color-gray-200);
    position: sticky;
    top: 0;
    z-index: 100;
    transition: box-shadow var(--transition-base);
}
.cdtsc-header.is-scrolled {
    box-shadow: var(--shadow-md);
}

.cdtsc-header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 120px;
    gap: var(--space-4);
}

/* Logo */
.cdtsc-logo { flex-shrink: 0; display: flex; align-items: center; }
.cdtsc-logo a { display: block; line-height: 0; }
.cdtsc-logo-img {
    height: 115px;
    width: auto;
    max-width: 600px;
    object-fit: contain;
    transition: opacity var(--transition-fast);
}
.cdtsc-logo a:hover .cdtsc-logo-img { opacity: 0.85; }

/* Navigation */
.cdtsc-nav {
    display: flex;
    align-items: center;
    gap: var(--space-1);
    list-style: none;
    margin: 0;
    padding: 0;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
}
.cdtsc-nav::-webkit-scrollbar { display: none; }
.cdtsc-nav li { list-style: none; margin: 0; padding: 0; flex-shrink: 0; }
.cdtsc-nav a {
    display: block;
    padding: var(--space-2) var(--space-4);
    color: var(--color-gray-600);
    font-size: var(--text-sm);
    font-weight: var(--fw-medium);
    border-radius: var(--radius-md);
    transition: all var(--transition-spring);
    white-space: nowrap;
    line-height: 1.5;
    position: relative;
}
.cdtsc-nav a::after {
    content: '';
    position: absolute;
    bottom: 2px;
    left: 50%;
    transform: translateX(-50%) scaleX(0);
    width: 55%;
    height: 2px;
    background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
    border-radius: var(--radius-full);
    transition: transform var(--transition-base);
}
.cdtsc-nav a:hover {
    color: var(--color-primary);
    background: var(--color-primary-50);
    transform: scale(1.1);
    box-shadow: var(--shadow-sm);
}
.cdtsc-nav a:hover::after {
    transform: translateX(-50%) scaleX(1);
}
.cdtsc-nav .current-menu-item a,
.cdtsc-nav .current a {
    color: var(--color-primary);
    background: var(--color-primary-50);
    font-weight: var(--fw-semibold);
    box-shadow: var(--shadow-xs);
}

/* Mobile toggle */
.cdtsc-mobile-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--space-2);
    border-radius: var(--radius-md);
}
.cdtsc-mobile-toggle:hover { background: var(--color-gray-100); }
.cdtsc-mobile-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--color-gray-700);
    margin: 5px 0;
    border-radius: 1px;
    transition: all var(--transition-base);
}
.cdtsc-mobile-toggle.is-active span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}
.cdtsc-mobile-toggle.is-active span:nth-child(2) {
    opacity: 0;
}
.cdtsc-mobile-toggle.is-active span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* Header actions */
.cdtsc-header-actions {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    flex-shrink: 0;
}
.cdtsc-lang-switch {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    font-size: var(--text-sm);
}
.cdtsc-lang-switch a {
    color: var(--color-gray-500);
    padding: var(--space-1) var(--space-2);
    border-radius: var(--radius-sm);
    font-weight: var(--fw-medium);
    font-size: var(--text-xs);
    transition: all var(--transition-fast);
}
.cdtsc-lang-switch a:hover { color: var(--color-primary); background: var(--color-primary-50); }
.cdtsc-lang-switch .current-lang a { color: var(--color-primary); font-weight: var(--fw-semibold); }

.cdtsc-header-btn {
    padding: var(--space-2) var(--space-4) !important;
    font-size: var(--text-sm) !important;
    font-weight: var(--fw-medium) !important;
    line-height: 1.4 !important;
    white-space: nowrap;
}

/* ============================================
   Hero
   ============================================ */

.cdtsc-hero {
    background: linear-gradient(170deg, #030f1f 0%, #051d3d 30%, #072d5c 60%, #094888 100%);
    color: var(--color-white);
    padding: var(--space-20) 0 var(--space-16);
    text-align: center;
    position: relative;
    overflow: hidden;
}

/* Ambient glow orbs */
.cdtsc-hero::before {
    content: '';
    position: absolute;
    top: -30%;
    right: -15%;
    width: 70%;
    height: 160%;
    background: radial-gradient(ellipse at center, rgba(14, 165, 233, 0.15) 0%, transparent 70%);
    pointer-events: none;
    animation: heroGlow 8s ease-in-out infinite alternate;
}
.cdtsc-hero::after {
    content: '';
    position: absolute;
    bottom: -20%;
    left: -10%;
    width: 50%;
    height: 100%;
    background: radial-gradient(ellipse at center, rgba(99, 102, 241, 0.08) 0%, transparent 70%);
    pointer-events: none;
    animation: heroGlow 10s ease-in-out 2s infinite alternate;
}
@keyframes heroGlow {
    0%   { opacity: 0.6; transform: scale(1); }
    100% { opacity: 1; transform: scale(1.08); }
}

/* Decorative shapes */
.cdtsc-hero-shape {
    position: absolute;
    border-radius: 50%;
    pointer-events: none;
    opacity: 0.06;
}
.cdtsc-hero-shape-1 {
    width: 400px; height: 400px;
    background: var(--color-accent);
    top: -100px; right: -80px;
}
.cdtsc-hero-shape-2 {
    width: 250px; height: 250px;
    background: #6366f1;
    bottom: -60px; left: -50px;
}
.cdtsc-hero-shape-3 {
    width: 150px; height: 150px;
    background: var(--color-accent);
    top: 50%; left: 15%;
    opacity: 0.04;
}

.cdtsc-hero .cdtsc-container { position: relative; z-index: 1; }

/* Hero text override — ensure white on dark bg */
.cdtsc-hero h1,
.cdtsc-hero h2,
.cdtsc-hero h3,
.cdtsc-hero h4,
.cdtsc-hero p,
.cdtsc-hero li {
    color: #ffffff !important;
}
.cdtsc-hero h1 { font-size: var(--text-4xl); font-weight: var(--fw-extrabold); margin-bottom: var(--space-4); }
.cdtsc-hero p { color: rgba(255, 255, 255, 0.85) !important; font-size: var(--text-lg); }

/* Hero Logo */
.cdtsc-hero-logo { margin-bottom: var(--space-6); }
.cdtsc-hero-logo-img {
    height: 140px;
    width: auto;
    margin: 0 auto;
    filter: drop-shadow(0 4px 24px rgba(14, 165, 233, 0.25));
    transition: transform var(--transition-slow);
}
.cdtsc-hero-logo-img:hover { transform: scale(1.03); }

/* Hero Subtitle */
.cdtsc-hero-subtitle {
    font-size: var(--text-xl);
    font-weight: var(--fw-normal);
    color: rgba(255, 255, 255, 0.75);
    max-width: 600px;
    margin: 0 auto var(--space-8);
    line-height: var(--leading-relaxed);
    letter-spacing: 0.01em;
}

/* Hero CTA */
.cdtsc-hero-actions {
    display: flex;
    gap: var(--space-4);
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: var(--space-12);
}
.cdtsc-btn-outline-white {
    color: var(--color-white);
    border-color: rgba(255, 255, 255, 0.3);
    background: rgba(255, 255, 255, 0.06);
    backdrop-filter: blur(4px);
}
.cdtsc-btn-outline-white:hover {
    border-color: rgba(255, 255, 255, 0.7);
    background: rgba(255, 255, 255, 0.14);
    color: var(--color-white);
    box-shadow: 0 0 20px rgba(14, 165, 233, 0.2);
}

/* Hero Stats */
.cdtsc-hero-stats {
    display: flex;
    justify-content: center;
    gap: var(--space-16);
    padding-top: var(--space-8);
    border-top: 1px solid rgba(255, 255, 255, 0.08);
}
.cdtsc-hero-stat { text-align: center; }
.cdtsc-hero-stat-number {
    font-size: var(--text-5xl);
    font-weight: var(--fw-extrabold);
    color: var(--color-white);
    line-height: 1;
    margin-bottom: var(--space-2);
    background: linear-gradient(180deg, #ffffff 0%, rgba(255,255,255,0.7) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}
.cdtsc-hero-stat-label {
    font-size: var(--text-xs);
    color: rgba(255, 255, 255, 0.5);
    font-weight: var(--fw-medium);
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

/* ============================================
   Quick Links
   ============================================ */

.cdtsc-quick-links {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--space-5);
    margin-top: calc(-1 * var(--space-6));
    position: relative;
    z-index: 2;
}
.cdtsc-quick-link {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-4);
    padding: var(--space-8) var(--space-4);
    background: var(--color-white);
    border: 1px solid var(--color-gray-100);
    border-radius: var(--radius-2xl);
    text-align: center;
    text-decoration: none;
    color: var(--color-gray-800);
    transition: all var(--transition-spring);
    box-shadow: var(--shadow-sm);
    position: relative;
    overflow: hidden;
}
.cdtsc-quick-link::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
    opacity: 0;
    transition: opacity var(--transition-base);
}
.cdtsc-quick-link:hover {
    border-color: var(--color-primary-200);
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
    color: var(--color-primary);
    text-decoration: none;
}
.cdtsc-quick-link:hover::before { opacity: 1; }

.cdtsc-quick-link-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 56px; height: 56px;
    border-radius: var(--radius-xl);
    background: linear-gradient(135deg, var(--color-primary-50), var(--color-accent-50));
    transition: all var(--transition-spring);
}
.cdtsc-quick-link:hover .cdtsc-quick-link-icon {
    background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
    transform: scale(1.05);
    box-shadow: var(--shadow-primary);
}
.cdtsc-quick-link-icon svg {
    width: 26px; height: 26px;
    color: var(--color-primary);
    transition: all var(--transition-base);
}
.cdtsc-quick-link:hover .cdtsc-quick-link-icon svg {
    color: var(--color-white);
}
.cdtsc-quick-link-label {
    font-size: var(--text-sm);
    font-weight: var(--fw-semibold);
    transition: all var(--transition-base);
}

/* ============================================
   Footer
   ============================================ */

.cdtsc-footer {
    background: var(--color-gray-900);
    color: var(--color-gray-400);
    padding: var(--space-20) 0 var(--space-8);
}
.cdtsc-footer a { transition: all var(--transition-fast); }

.cdtsc-footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: var(--space-12);
    margin-bottom: var(--space-12);
}
.cdtsc-footer-brand img {
    display: block;
    height: 56px;
    width: auto;
    margin: 0 0 var(--space-4) 0;
    opacity: 0.85;
    transition: opacity var(--transition-fast);
}
.cdtsc-footer-brand img:hover { opacity: 1; }
.cdtsc-footer-brand-text {
    display: flex;
    flex-direction: column;
    gap: var(--space-1);
    margin-bottom: var(--space-4);
}
.cdtsc-footer-brand-en {
    font-size: var(--text-2xl);
    font-weight: var(--fw-extrabold);
    color: var(--color-white);
    line-height: var(--leading-tight);
    letter-spacing: 0.03em;
}
.cdtsc-footer-brand-zh {
    font-size: var(--text-xl);
    font-weight: var(--fw-bold);
    color: rgba(255, 255, 255, 0.85);
    line-height: var(--leading-tight);
    letter-spacing: 0.06em;
}
.cdtsc-footer-brand p { color: var(--color-gray-500); font-size: var(--text-sm); line-height: var(--leading-relaxed); max-width: 400px; }
.cdtsc-footer h4 {
    color: var(--color-white);
    font-size: var(--text-xs);
    font-weight: var(--fw-semibold);
    margin-bottom: var(--space-5);
    text-transform: uppercase;
    letter-spacing: 0.08em;
}
.cdtsc-footer ul { list-style: none; padding: 0; margin: 0; }
.cdtsc-footer ul li { margin-bottom: var(--space-3); }
.cdtsc-footer ul li a { color: var(--color-gray-500); font-size: var(--text-sm); transition: all var(--transition-fast); }
.cdtsc-footer ul li a:hover { color: var(--color-white); padding-left: var(--space-1); }

.cdtsc-footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.06);
    padding-top: var(--space-8);
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: var(--text-sm);
    color: var(--color-gray-600);
    flex-wrap: wrap;
    gap: var(--space-4);
}
.cdtsc-footer-bottom-links { display: flex; gap: var(--space-6); }
.cdtsc-footer-bottom-links a { color: var(--color-gray-600); font-size: var(--text-sm); }
.cdtsc-footer-bottom-links a:hover { color: var(--color-white); }

/* ============================================
   Sidebar (inner pages)
   ============================================ */

.cdtsc-content-with-sidebar {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: var(--space-10);
    align-items: start;
}
.cdtsc-sidebar { position: sticky; top: 88px; }

/* ---- Standard Project Cards - Show/Hide ---- */
.cdtsc-standard-hidden {
    display: none;
    opacity: 0;
    transform: translateY(12px);
    transition: opacity 0.4s ease, transform 0.4s ease;
}
.cdtsc-standard-hidden.is-visible {
    display: flex;
    opacity: 1;
    transform: translateY(0);
}
#cdtsc-toggle-standards {
    cursor: pointer;
    font-size: var(--text-sm);
    transition: all var(--transition-base);
}

/* ============================================
   Empty State
   ============================================ */

.cdtsc-empty {
    text-align: center;
    padding: var(--space-16) var(--space-4);
}
.cdtsc-empty-icon {
    display: block;
    width: 64px; height: 64px;
    margin: 0 auto var(--space-5);
    color: var(--color-gray-300);
}
.cdtsc-empty p {
    font-size: var(--text-base);
    color: var(--color-gray-400);
}

/* ============================================
   Responsive
   ============================================ */

@media (max-width: 1024px) {
    .cdtsc-grid-4 { grid-template-columns: repeat(2, 1fr); }
    .cdtsc-footer-grid { grid-template-columns: repeat(2, 1fr); }
    .cdtsc-content-with-sidebar { grid-template-columns: 1fr; }
    .cdtsc-sidebar { position: static; }

    .cdtsc-section { padding: var(--space-16) 0; }
    .cdtsc-section-title h2 { font-size: var(--text-2xl); }
    .cdtsc-hero { padding: var(--space-16) 0 var(--space-12); }
    .cdtsc-hero-stats { gap: var(--space-10); }
}

@media (max-width: 768px) {
    .cdtsc-grid-2,
    .cdtsc-grid-3 { grid-template-columns: 1fr; }

    /* Header — mobile */
    .cdtsc-header-inner {
        height: auto;
        min-height: 64px;
        padding: var(--space-3) 0;
        gap: var(--space-2);
        flex-wrap: wrap;
    }
    .cdtsc-header { position: sticky; }
    .cdtsc-logo-img { height: 64px; max-width: 320px; }

    .cdtsc-mobile-toggle {
        display: block;
        position: absolute;
        top: var(--space-3);
        right: var(--space-4);
        z-index: 10;
    }
    .cdtsc-nav {
        display: none;
        flex-direction: column;
        width: 100%;
        order: 10;
        gap: 0;
        padding: var(--space-2) 0;
    }
    .cdtsc-nav.is-open {
        display: flex;
        animation: fadeInUp 0.25s ease;
    }
    .cdtsc-nav a {
        padding: var(--space-3) var(--space-4);
        border-bottom: 1px solid var(--color-gray-100);
        border-radius: 0;
        font-size: var(--text-base);
    }
    .cdtsc-header-actions {
        margin-left: auto;
        margin-right: var(--space-12);
    }

    /* Hero */
    .cdtsc-hero { padding: var(--space-12) 0 var(--space-8); }
    .cdtsc-hero-logo-img { height: 100px; }
    .cdtsc-hero-subtitle { font-size: var(--text-base); padding: 0 var(--space-2); }
    .cdtsc-hero-actions { flex-direction: column; align-items: center; }
    .cdtsc-hero-stats { gap: var(--space-6); flex-wrap: wrap; }
    .cdtsc-hero-stat-number { font-size: var(--text-4xl); }

    /* Quick Links */
    .cdtsc-quick-links {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-3);
        margin-top: calc(-1 * var(--space-4));
    }
    .cdtsc-quick-link { padding: var(--space-5) var(--space-3); border-radius: var(--radius-xl); }
    .cdtsc-quick-link-icon { width: 48px; height: 48px; }

    /* Sections */
    .cdtsc-section { padding: var(--space-12) 0; }
    .cdtsc-section-title { margin-bottom: var(--space-8); }
    .cdtsc-section-title h2 { font-size: var(--text-2xl); }

    /* Footer */
    .cdtsc-footer { padding: var(--space-12) 0 var(--space-6); }
    .cdtsc-footer-grid { grid-template-columns: 1fr; gap: var(--space-8); }
    .cdtsc-footer-bottom { flex-direction: column; gap: var(--space-4); text-align: center; }
    .cdtsc-footer-bottom-links { justify-content: center; }
}

@media (max-width: 480px) {
    .cdtsc-quick-links { gap: var(--space-2); }
    .cdtsc-hero-stats { gap: var(--space-4); }
    .cdtsc-hero-stat-number { font-size: var(--text-3xl); }
    .cdtsc-section { padding: var(--space-10) 0; }
}