:root {
    /* Dark Theme Palette */
    --bg-main: #0a0a0a;
    --bg-card: #161616;
    --bg-card-hover: #1f1f1f;
    --text-main: #ffffff;
    --text-muted: #a1a1aa;
    
    /* Neon Accents */
    --accent-primary: #3b82f6; /* Blue */
    --accent-secondary: #8b5cf6; /* Purple */
    --accent-glow: rgba(59, 130, 246, 0.5);
    
    /* UI Elements */
    --nav-glass: rgba(10, 10, 10, 0.7);
    --border-color: rgba(255, 255, 255, 0.1);
    --radius-lg: 16px;
    --radius-md: 12px;
    
    --transition-smooth: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background-color: var(--bg-main);
    color: var(--text-main);
    line-height: 1.6;
    overflow-x: hidden;
    /* Custom Cursor only on desktop */
}

@media (min-width: 992px) {
    body {
        /* Default Cursor: Cyan Hollow "V" */
        cursor: url("data:image/svg+xml,%3Csvg width='32' height='32' viewBox='0 0 32 32' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M0 0L11 30L15 15L30 11L0 0Z' fill='%2300FFFF' fill-opacity='0.2' stroke='%2300FFFF' stroke-width='2' stroke-linejoin='round'/%3E%3Cpath d='M0 0L7 19L10 10L19 7L0 0Z' fill='%2300FFFF'/%3E%3C/svg%3E") 0 0, auto;
    }
    
    /* Hover Cursor: Red Target "V" */
    a, button, .video-card, .hero__cta, .contact__card, .certificate-download {
        cursor: url("data:image/svg+xml,%3Csvg width='32' height='32' viewBox='0 0 32 32' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M0 0L11 30L15 15L30 11L0 0Z' fill='%23FF0044' fill-opacity='0.2' stroke='%23FF0044' stroke-width='2' stroke-linejoin='round'/%3E%3Cpath d='M0 0L7 19L10 10L19 7L0 0Z' fill='%23FF0044'/%3E%3C/svg%3E") 0 0, pointer;
    }
}

/* --- Navbar --- */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    background: var(--nav-glass);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
    transition: transform 0.3s ease;
}

.navbar--hidden {
    transform: translateY(-100%);
}

.navbar__container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.navbar__logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--text-main);
    text-decoration: none;
    letter-spacing: -0.05em;
}

.navbar__menu {
    display: flex;
    gap: 2rem;
    list-style: none;
    align-items: center;
}

.navbar__menu a {
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 500;
    transition: color 0.2s;
}

.navbar__menu a:hover {
    color: var(--text-main);
}

.navbar__btn {
    padding: 8px 20px;
    background: rgba(255,255,255,0.1);
    border-radius: 99px;
    color: var(--text-main) !important;
    border: 1px solid transparent;
    transition: var(--transition-smooth) !important;
}

.navbar__btn:hover {
    background: var(--text-main);
    color: var(--bg-main) !important;
}

/* --- Hero Section --- */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    overflow: hidden;
    padding: 0 1.5rem;
}

.hero__bg {
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at center, #1a237e 0%, #000000 50%);
    opacity: 0.4;
    animation: rotateBg 20s linear infinite;
    z-index: 0;
}

@keyframes rotateBg {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.hero__content {
    position: relative;
    z-index: 2;
    max-width: 800px;
}

.hero__title {
    font-size: clamp(3rem, 8vw, 5.5rem);
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 1.5rem;
    letter-spacing: -0.02em;
}

.accent {
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.cursor {
    font-weight: 100;
    color: var(--accent-primary);
    animation: blink 1s infinite;
}

@keyframes blink { 50% { opacity: 0; } }

.hero__subtitle {
    font-size: clamp(1.1rem, 2vw, 1.4rem);
    color: var(--text-muted);
    margin-bottom: 3rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero__actions {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    align-items: center;
}

.hero__cta {
    padding: 14px 36px;
    background: var(--accent-primary);
    color: white;
    border-radius: 99px;
    font-weight: 600;
    text-decoration: none;
    box-shadow: 0 0 20px var(--accent-glow);
    transition: var(--transition-smooth);
}

.hero__cta:hover {
    transform: translateY(-2px);
    box-shadow: 0 0 40px var(--accent-glow);
}

.hero__link {
    color: var(--text-main);
    text-decoration: none;
    font-weight: 500;
    border-bottom: 1px solid rgba(255,255,255,0.3);
    padding-bottom: 2px;
}

/* --- General Sections --- */
.section-padding {
    padding: 6rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.section-title {
    font-size: clamp(2rem, 4vw, 3rem);
    margin-bottom: 1rem;
    background: linear-gradient(to right, #fff, #666);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.section-header {
    text-align: center;
    margin-bottom: 5rem;
}

.section-header p {
    color: var(--text-muted);
    font-size: 1.2rem;
}

/* --- About Cards --- */
.about__cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.info-card {
    background: var(--bg-card);
    padding: 2.5rem;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    position: relative;
    overflow: hidden;
    transition: var(--transition-smooth);
}

.info-card h3 {
    margin-bottom: 1.5rem;
    font-size: 1.5rem;
}

.info-card ul li {
    list-style: none;
    color: var(--text-muted);
    margin-bottom: 0.8rem;
    padding-left: 1.2rem;
    position: relative;
}

.info-card ul li::before {
    content: "•";
    color: var(--accent-primary);
    position: absolute;
    left: 0;
    font-weight: bold;
}

.highlight {
    color: var(--accent-primary);
    font-weight: 600;
}

/* --- Video Grid --- */
.video__list {
    display: flex;
    flex-direction: column;
    gap: 6rem;
}

.video__group-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 2rem;
}

.group-tag {
    font-size: 3rem;
    font-weight: 900;
    color: rgba(255,255,255,0.05);
    line-height: 1;
}

.video__group-title {
    font-size: 1.5rem;
    color: var(--text-main);
}

.video__grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.video-card {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    overflow: hidden;
    border: 1px solid var(--border-color);
    transition: var(--transition-smooth);
    transform-style: preserve-3d; /* For tilt */
}

.video-card:hover {
    border-color: rgba(255,255,255,0.2);
    box-shadow: 0 20px 40px rgba(0,0,0,0.3);
}

.video-card__thumb {
    position: relative;
    aspect-ratio: 16/9;
    background: #000;
}

.video-card__thumb iframe {
    width: 100%;
    height: 100%;
    pointer-events: auto; /* Enable Bilibili controls */
}

.video-card__badge {
    position: absolute;
    top: 10px;
    right: 10px;
    background: rgba(0,0,0,0.6);
    backdrop-filter: blur(4px);
    padding: 4px 10px;
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-main);
    border: 1px solid rgba(255,255,255,0.1);
}

.video-card__body {
    padding: 1.5rem;
}

.video-card__body h3 {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
    color: var(--text-main);
}

.video-card__body p {
    color: var(--text-muted);
    font-size: 0.9rem;
}

/* --- Contact --- */
.contact__container {
    display: flex;
    flex-wrap: wrap;
    gap: 1.5rem;
    justify-content: center;
    margin-top: 3rem;
}

.contact__card {
    background: var(--bg-card);
    padding: 1.5rem 2.5rem;
    border-radius: var(--radius-lg);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 1rem;
    border: 1px solid var(--border-color);
    transition: var(--transition-smooth);
}

.contact__card:hover {
    background: var(--bg-card-hover);
    transform: translateY(-5px);
    border-color: var(--accent-primary);
}

.contact__card .icon {
    font-size: 2rem;
}

.contact__card .detail {
    display: flex;
    flex-direction: column;
}

.contact__card .label {
    font-size: 0.8rem;
    color: var(--text-muted);
    text-transform: uppercase;
}

.contact__card .value {
    color: var(--text-main);
    font-weight: 600;
}

/* --- Footer --- */
.footer {
    text-align: center;
    padding: 3rem;
    border-top: 1px solid var(--border-color);
    color: #444;
    font-size: 0.9rem;
}

/* --- Utilities & Animation Classes --- */
.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.8s cubic-bezier(0.5, 0, 0, 1);
}

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

/* Certificate Specific */
.certificate-viewer {
    background: #222;
    height: 300px;
    border-radius: 8px;
    margin: 1rem 0;
    overflow: hidden;
}

.certificate-download {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    padding: 12px;
    background: rgba(255,255,255,0.05);
    color: var(--text-main);
    text-decoration: none;
    border-radius: 8px;
    font-size: 0.9rem;
    gap: 8px;
    transition: 0.3s;
}

.certificate-download:hover {
    background: var(--accent-primary);
}

/* Responsive */
@media (max-width: 768px) {
    .navbar__menu { display: none; } /* Simple hide for mobile, or add hamburger logic */
    .hero__title { font-size: 2.5rem; }
}

#click-canvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 9999;
}