/* Global Styles - Theme: Modern Light */
:root {
    --primary-color: #2563eb; /* Royal Blue */
    --secondary-color: #059669; /* Emerald */
    --bg-color: #f8fafc; /* Slate 50 */
    --card-bg: #ffffff; /* White */
    --text-color: #1e293b; /* Slate 800 */
    --text-muted: #64748b; /* Slate 500 */
    --white: #ffffff;
    --hero-text: #ffffff; /* Specific for Hero section */
    --gradient: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1);
}

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

body {
    font-family: 'Segoe UI', 'Roboto', 'Helvetica Neue', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    overflow-x: hidden;
}

a {
    text-decoration: none;
    color: inherit;
    transition: 0.3s;
}

ul {
    list-style: none;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 40px;
}

.section {
    padding: 80px 0;
}

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-header h2 {
    font-size: 2.5rem;
    margin-bottom: 15px;
    background: var(--gradient);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.section-header .line {
    width: 60px;
    height: 4px;
    background: var(--gradient);
    margin: 0 auto;
    border-radius: 2px;
}

/* Navbar */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    padding: 20px 0;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    z-index: 1000;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    transition: all 0.3s ease;
}

.navbar.scrolled {
    background: rgba(255, 255, 255, 0.98);
    padding: 15px 0;
    box-shadow: var(--shadow-md);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 24px;
}

.logo {
    display: inline-flex;
    align-items: center;
    gap: 14px;
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--primary-color); /* Darker logo for light theme */
    letter-spacing: 1px;
    max-width: 52%;
    line-height: 1.4;
}

.brand-mark {
    width: 48px;
    height: 48px;
    object-fit: contain;
    flex-shrink: 0;
}

.logo span {
    display: block;
}

.nav-links {
    display: flex;
    gap: 22px;
    flex-wrap: wrap;
    justify-content: flex-end;
}

.nav-links a {
    color: var(--text-color);
    font-weight: 500;
    position: relative;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: 0.3s;
}

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

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

.hamburger {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-color);
}

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

.hero-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
}

.hero-bg img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center right;
    transition: opacity 0.3s ease; /* Add transition for smooth image switching */
}

.hero-bg .overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    /* Dark overlay is still needed for text readability on the dark image */
    background: linear-gradient(to bottom, rgba(15, 23, 42, 0.4), rgba(15, 23, 42, 0.1)); 
}

/* Add a white fade at the bottom to blend into the light section */
.hero-bg .overlay::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 150px;
    background: linear-gradient(to bottom, transparent, var(--bg-color));
}

.hero-content {
    width: 100%;
    z-index: 1;
}

.hero-content h1 {
    font-size: 4rem;
    line-height: 1.2;
    margin-bottom: 20px;
    color: var(--hero-text);
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
    max-width: 650px;
}

.hero-content p {
    font-size: 1.5rem;
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: 40px;
    max-width: 600px;
    text-shadow: 0 1px 5px rgba(0, 0, 0, 0.3);
}

.hero-organizers {
    display: inline-flex;
    flex-direction: column;
    gap: 8px;
    max-width: min(920px, 100%);
    margin-bottom: 32px;
    padding-left: 18px;
    border-left: 3px solid rgba(255, 255, 255, 0.5);
}

.hero-organizers p {
    display: flex;
    flex-wrap: wrap;
    align-items: baseline;
    gap: 0.35rem;
    margin: 0;
    font-size: clamp(0.94rem, 0.86rem + 0.22vw, 1rem);
    line-height: 1.7;
    color: rgba(255, 255, 255, 0.96);
    text-shadow: 0 1px 6px rgba(0, 0, 0, 0.18);
}

.hero-organizers strong {
    white-space: nowrap;
    flex: 0 0 auto;
}

.hero-organizers span {
    flex: 1 1 520px;
    min-width: 0;
}

.hero-content .cta-buttons {
    display: flex;
    gap: 20px;
}

.btn {
    display: inline-block;
    padding: 12px 30px;
    border-radius: 30px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin: 0;
}

.btn-primary {
    background: var(--gradient);
    color: var(--white);
    box-shadow: 0 4px 15px rgba(37, 99, 235, 0.3);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(37, 99, 235, 0.4);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.1);
    border: 2px solid var(--white);
    color: var(--white);
    backdrop-filter: blur(5px);
}

.btn-secondary:hover {
    background: var(--white);
    color: var(--primary-color);
}

/* Animations */
.animate-up {
    opacity: 0;
    transform: translateY(30px);
    animation: fadeInUp 0.8s forwards;
}

.delay-1 { animation-delay: 0.2s; }
.delay-2 { animation-delay: 0.4s; }

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Intro Section */
.intro p {
    font-size: 1.2rem;
    max-width: 800px;
    margin: 0 auto;
    color: var(--text-muted);
}

/* Tracks Section */
.tracks-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.track-card {
    background: var(--card-bg);
    padding: 40px;
    border-radius: 15px;
    border: 1px solid rgba(0, 0, 0, 0.05);
    box-shadow: var(--shadow-sm);
    transition: 0.3s;
    position: relative;
    overflow: hidden;
}

.track-card:hover {
    transform: translateY(-10px);
    border-color: var(--primary-color);
    box-shadow: var(--shadow-lg);
}

.track-card .icon {
    font-size: 3rem;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.track-card h3 {
    font-size: 1.5rem;
    margin-bottom: 15px;
    color: var(--text-color);
}

.track-card p {
    color: var(--text-muted);
    margin-bottom: 25px;
}

.btn-text {
    color: var(--primary-color);
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 5px;
}

.btn-text:hover {
    gap: 10px;
}

/* Rewards Section */
.rewards-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 50px;
}

.reward-box {
    text-align: center;
    padding: 40px;
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.05), rgba(5, 150, 105, 0.05));
    border-radius: 20px;
    border: 1px solid rgba(37, 99, 235, 0.1);
}

.reward-box .number {
    display: block;
    font-size: 4rem;
    font-weight: 800;
    background: var(--gradient);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    line-height: 1;
    margin-bottom: 10px;
}

.reward-box .label {
    font-size: 1.2rem;
    color: var(--text-color);
    text-transform: uppercase;
    letter-spacing: 2px;
    font-weight: 600;
}

.reward-features {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 30px;
    width: 100%;
}

.feature {
    flex: 1;
    min-width: 250px;
    text-align: center;
    padding: 30px;
    background: var(--card-bg);
    border-radius: 15px;
    box-shadow: var(--shadow-sm);
    border: 1px solid rgba(0,0,0,0.05);
}

.feature i {
    font-size: 2.5rem;
    color: var(--secondary-color);
    margin-bottom: 20px;
}

.feature h4 {
    font-size: 1.2rem;
    color: var(--text-color);
    margin-bottom: 10px;
}

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

/* Schedule Section */
.timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}

.timeline::after {
    content: '';
    position: absolute;
    width: 2px;
    background: rgba(0, 0, 0, 0.1);
    top: 0;
    bottom: 0;
    left: 50%;
    margin-left: -1px;
}

.timeline-item {
    padding: 10px 40px;
    position: relative;
    background-color: inherit;
    width: 50%;
}

.timeline-item::after {
    content: '';
    position: absolute;
    width: 16px;
    height: 16px;
    right: -8px;
    background-color: var(--bg-color);
    border: 2px solid var(--primary-color);
    top: 20px;
    border-radius: 50%;
    z-index: 1;
}

.timeline-item:nth-child(odd) {
    left: 0;
    text-align: right;
}

.timeline-item:nth-child(even) {
    left: 50%;
}

.timeline-item:nth-child(even)::after {
    left: -8px;
}

.timeline-item .date {
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 5px;
}

.timeline-item .content {
    padding: 20px;
    background: var(--card-bg);
    border-radius: 10px;
    border: 1px solid rgba(0, 0, 0, 0.05);
    box-shadow: var(--shadow-sm);
}

.timeline-item .content h3 {
    color: var(--text-color);
    margin-bottom: 5px;
}

.timeline-item .content p {
    font-size: 0.9rem;
    color: var(--text-muted);
}

/* Contact Section */
.contact-info {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 30px;
}

.contact-item {
    text-align: center;
    padding: 30px;
    background: var(--card-bg);
    border-radius: 15px;
    min-width: 250px;
    transition: 0.3s;
    box-shadow: var(--shadow-sm);
    border: 1px solid rgba(0,0,0,0.05);
}

.contact-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

.contact-item i {
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: 15px;
}

.contact-item h4 {
    color: var(--text-color);
    margin-bottom: 10px;
}

.contact-item p {
    color: var(--text-muted);
}

.qq-group-number {
    margin-bottom: 12px;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-color);
}

.qq-qr {
    width: 150px;
    height: 150px;
    object-fit: cover;
    border-radius: 10px;
    margin: 0;
    border: 1px solid rgba(0,0,0,0.1);
}

/* Footer */
footer {
    background: #1e293b; /* Keep footer dark for contrast */
    padding: 30px 0;
    text-align: center;
    color: #94a3b8;
    font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 768px) {
    .hero-content h1 {
        font-size: 2.5rem;
    }

    .hero-content p {
        font-size: 1.1rem;
        margin-bottom: 24px;
    }

    .hero-organizers {
        display: flex;
        gap: 10px;
        max-width: 100%;
        padding-left: 14px;
        margin-bottom: 24px;
        border-left-width: 2px;
    }

    .hero-organizers p {
        font-size: 0.95rem;
        line-height: 1.7;
    }

    .hero-organizers span {
        flex-basis: 100%;
    }

    .logo {
        max-width: calc(100% - 56px);
        gap: 10px;
        font-size: 0.9rem;
        letter-spacing: 0.4px;
    }

    .brand-mark {
        width: 40px;
        height: 40px;
    }
    
    .nav-links {
        display: none;
        position: absolute;
        top: 70px;
        left: 0;
        width: 100%;
        background: var(--card-bg);
        flex-direction: column;
        padding: 20px;
        text-align: center;
        border-bottom: 1px solid rgba(0, 0, 0, 0.1);
        box-shadow: var(--shadow-md);
    }

    .nav-links.active {
        display: flex;
    }

    .hamburger {
        display: block;
    }

    .cta-buttons {
        flex-direction: column;
        align-items: flex-start;
    }

    .btn {
        width: 100%;
        text-align: center;
    }

    .timeline::after {
        left: 31px;
    }

    .timeline-item {
        width: 100%;
        padding-left: 70px;
        padding-right: 25px;
    }

    .timeline-item::after {
        left: 23px;
    }

    .timeline-item:nth-child(odd) {
        left: 0;
        text-align: left;
    }
    
    .timeline-item:nth-child(odd)::after {
        left: 23px;
    }
}