/* ===== RESET & BASE STYLES ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Modern Color Palette */
    --primary-color: #667eea;
    --primary-dark: #5a67d8;
    --primary-light: #a5b4fc;
    --secondary-color: #f093fb;
    --accent-color: #4fd1c7;
    --success-color: #48bb78;
    --warning-color: #ed8936;
    --error-color: #f56565;
    
    /* Text Colors */
    --text-primary: #2d3748;
    --text-secondary: #4a5568;
    --text-light: #718096;
    --text-white: #ffffff;
    
    /* Background Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f7fafc;
    --bg-tertiary: #edf2f7;
    --bg-dark: #1a202c;
    --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --bg-gradient-light: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    
    /* Border & Shadow */
    --border-color: #e2e8f0;
    --border-radius: 12px;
    --border-radius-lg: 20px;
    --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* ===== NAVIGATION ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    padding: 1rem 0;
}

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

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--primary-color);
}

.logo-icon {
    font-size: 1.5rem;
}

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

.btn-signin {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.btn-signin:hover {
    background: var(--primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

/* ===== MAIN CONTENT ===== */
.main-content {
    margin-top: 80px;
}

/* ===== HERO SECTION ===== */
.hero {
    padding: 6rem 0;
    background: var(--bg-gradient);
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><defs><pattern id="grid" width="20" height="20" patternUnits="userSpaceOnUse"><path d="M 20 0 L 0 0 0 20" fill="none" stroke="rgba(255,255,255,0.1)" stroke-width="1"/></pattern></defs><rect width="100" height="100" fill="url(%23grid)"/></svg>');
    opacity: 0.3;
}

.hero-content {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 2rem;
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 6rem;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-text {
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.hero-title {
    font-size: 4.5rem;
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 2rem;
    color: var(--text-white);
    text-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

.highlight {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    position: relative;
}

.hero-subtitle {
    font-size: 1.5rem;
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: 3rem;
    line-height: 1.7;
    font-weight: 400;
}

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

.btn-primary {
    background: var(--text-white);
    color: var(--primary-color);
    border: none;
    padding: 1.25rem 2.5rem;
    border-radius: var(--border-radius);
    font-weight: 700;
    font-size: 1.1rem;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
}

.btn-primary::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s;
}

.btn-primary:hover::before {
    left: 100%;
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-2xl);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-white);
    border: 2px solid rgba(255, 255, 255, 0.3);
    padding: 1.25rem 2.5rem;
    border-radius: var(--border-radius);
    font-weight: 700;
    font-size: 1.1rem;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.2);
    border-color: rgba(255, 255, 255, 0.5);
    transform: translateY(-3px);
    box-shadow: var(--shadow-xl);
}

.hero-visual {
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
}

.code-animation {
    background: rgba(26, 32, 44, 0.9);
    padding: 3rem;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-2xl);
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    color: #e2e8f0;
    min-width: 400px;
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    position: relative;
    overflow: hidden;
}

.code-animation::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, #f093fb, #f5576c, #4fd1c7);
}

.code-line {
    margin-bottom: 0.75rem;
    font-size: 1rem;
    line-height: 1.6;
    opacity: 0;
    animation: fadeInUp 0.6s ease-out forwards;
}

.code-line:nth-child(1) { animation-delay: 0.1s; }
.code-line:nth-child(2) { animation-delay: 0.3s; }
.code-line:nth-child(3) { animation-delay: 0.5s; }
.code-line:nth-child(4) { animation-delay: 0.7s; }

.code-line:last-child {
    margin-bottom: 0;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ===== SECTIONS ===== */
section {
    padding: 5rem 0;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

/* ===== CHALLENGE SECTION ===== */
.challenge {
    background: var(--bg-secondary);
}

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

.challenge-card {
    background: white;
    padding: 2rem;
    border-radius: 1rem;
    text-align: center;
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
}

.challenge-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.card-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.challenge-card h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.challenge-card p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* ===== LEADERBOARD SECTION ===== */
.leaderboard {
    background: var(--bg-secondary);
    padding: 6rem 0;
}

.leaderboard-container {
    background: var(--text-white);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-xl);
    overflow: hidden;
    border: 1px solid var(--border-color);
    max-width: 1000px;
    margin: 0 auto;
}

.leaderboard-header {
    display: grid;
    grid-template-columns: 100px 1fr 140px 140px;
    gap: 2rem;
    padding: 2rem;
    background: var(--bg-gradient);
    font-weight: 700;
    color: var(--text-white);
    font-size: 1.1rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.leaderboard-entries {
    max-height: 500px;
    overflow-y: auto;
}

.leaderboard-entries::-webkit-scrollbar {
    width: 8px;
}

.leaderboard-entries::-webkit-scrollbar-track {
    background: var(--bg-tertiary);
}

.leaderboard-entries::-webkit-scrollbar-thumb {
    background: var(--primary-color);
    border-radius: 4px;
}

.leaderboard-entry {
    display: grid;
    grid-template-columns: 100px 1fr 140px 140px;
    gap: 2rem;
    padding: 1.5rem 2rem;
    border-bottom: 1px solid var(--border-color);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
}

.leaderboard-entry:hover {
    background: var(--bg-secondary);
    transform: translateX(8px);
    box-shadow: var(--shadow-md);
}

.leaderboard-entry:last-child {
    border-bottom: none;
}

.empty-leaderboard {
    text-align: center;
    padding: 3rem 2rem;
    color: rgba(255, 255, 255, 0.7);
    background: rgba(255, 255, 255, 0.05);
    border-radius: 12px;
    border: 2px dashed rgba(255, 255, 255, 0.2);
    margin: 2rem 0;
}

.empty-leaderboard p {
    margin: 0.5rem 0;
    font-size: 1.1rem;
}

.empty-leaderboard p:first-child {
    font-size: 1.5rem;
    font-weight: 600;
    color: #ffd700;
}

/* Submission Modal Styles */
.submission-instructions {
    max-width: 800px;
    margin: 0 auto;
}

.welcome-section {
    text-align: center;
    margin-bottom: 2rem;
    padding: 1.5rem;
    background: rgba(255, 215, 0, 0.1);
    border-radius: 15px;
    border: 1px solid rgba(255, 215, 0, 0.2);
}

.welcome-section h3 {
    color: #ffd700;
    margin-bottom: 0.5rem;
    font-size: 1.8rem;
    font-weight: 700;
}

.welcome-section p {
    color: #e0e0e0;
    font-size: 1.1rem;
    margin: 0;
}

.steps-container {
    margin: 2rem 0;
}

.steps-container h4 {
    color: #ffffff;
    margin-bottom: 1.5rem;
    font-size: 1.3rem;
    font-weight: 600;
    text-align: center;
}

.step-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.step-card {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 15px;
    padding: 1.5rem;
    text-align: center;
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
}

.step-card:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: #ffd700;
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(255, 215, 0, 0.2);
}

.step-number {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, #ffd700 0%, #ffed4e 100%);
    color: #1a1a2e;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.2rem;
    margin: 0 auto 1rem auto;
    box-shadow: 0 4px 15px rgba(255, 215, 0, 0.3);
}

.step-content h5 {
    color: #ffd700;
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
    font-weight: 600;
}

.step-content p {
    color: #e0e0e0;
    font-size: 0.9rem;
    margin: 0;
    line-height: 1.4;
}

.motivation-text {
    text-align: center;
    margin-top: 2rem;
    padding: 1rem;
    background: rgba(99, 102, 241, 0.1);
    border-radius: 10px;
    border: 1px solid rgba(99, 102, 241, 0.2);
}

.motivation-text p {
    color: #e0e0e0;
    margin: 0;
    font-size: 1rem;
}

.motivation-text strong {
    color: #ffd700;
}

.submission-instructions h3 {
    color: #ffd700;
    margin-bottom: 1.5rem;
    font-size: 1.5rem;
    font-weight: 700;
    text-align: center;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.submission-instructions ol {
    margin: 1.5rem 0;
    padding-left: 1.5rem;
}

.submission-instructions li {
    margin: 1rem 0;
    line-height: 1.8;
    color: #e0e0e0;
    font-size: 1.1rem;
}

.submission-instructions code {
    background: rgba(255, 215, 0, 0.2);
    padding: 0.3rem 0.6rem;
    border-radius: 6px;
    font-family: 'Courier New', monospace;
    color: #ffd700;
    border: 1px solid rgba(255, 215, 0, 0.3);
}

.language-tabs {
    margin: 2rem 0;
}

.language-tabs h4 {
    color: #ffffff;
    margin-bottom: 1.5rem;
    font-size: 1.2rem;
    font-weight: 600;
    text-align: center;
}

.tab-buttons {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.tab-btn {
    padding: 0.8rem 1.5rem;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 12px;
    color: #e0e0e0;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1rem;
    font-weight: 500;
    backdrop-filter: blur(10px);
}

.tab-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    border-color: #ffd700;
    transform: translateY(-2px);
}

.tab-btn.active {
    background: linear-gradient(135deg, #ffd700 0%, #ffed4e 100%);
    color: #1a1a2e;
    border-color: #ffd700;
    box-shadow: 0 4px 15px rgba(255, 215, 0, 0.3);
}

.code-example {
    background: rgba(0, 0, 0, 0.3);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 15px;
    padding: 1.5rem;
    margin: 1.5rem 0;
    backdrop-filter: blur(10px);
}

.code-example h5 {
    color: #ffd700;
    margin-bottom: 1rem;
    font-size: 1.2rem;
    font-weight: 600;
}

.code-example pre {
    background: #0a0a0a;
    border-radius: 10px;
    padding: 1.5rem;
    overflow-x: auto;
    margin: 0;
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.3);
}

.code-example code {
    color: #e6e6e6;
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    line-height: 1.5;
}

.submission-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-top: 2rem;
    flex-wrap: wrap;
}

.submission-actions .btn-primary,
.submission-actions .btn-secondary {
    padding: 0.8rem 2rem;
    border-radius: 8px;
    font-weight: 600;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
}

.submission-actions .btn-primary {
    background: linear-gradient(135deg, #ffd700 0%, #ffed4e 100%);
    color: #1a1a2e;
    font-weight: 700;
    box-shadow: 0 4px 15px rgba(255, 215, 0, 0.3);
}

.submission-actions .btn-primary:hover {
    background: linear-gradient(135deg, #ffed4e 0%, #ffd700 100%);
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(255, 215, 0, 0.4);
}

.submission-actions .btn-secondary {
    background: rgba(255, 255, 255, 0.1);
    color: #ffffff;
    border: 1px solid rgba(255, 255, 255, 0.2);
    backdrop-filter: blur(10px);
}

.submission-actions .btn-secondary:hover {
    background: rgba(255, 255, 255, 0.2);
    border-color: #ffd700;
    color: #ffd700;
}

.rank {
    font-weight: 800;
    font-size: 1.2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--bg-gradient);
    color: var(--text-white);
    box-shadow: var(--shadow-md);
}

.user {
    font-weight: 600;
    font-size: 1.1rem;
    color: var(--text-primary);
    display: flex;
    align-items: center;
}

.time {
    font-family: 'Monaco', 'Menlo', monospace;
    color: var(--success-color);
    font-weight: 700;
    font-size: 1.1rem;
    display: flex;
    align-items: center;
}

.language {
    text-transform: uppercase;
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    padding: 0.5rem 1rem;
    background: var(--bg-tertiary);
    border-radius: var(--border-radius);
    width: fit-content;
}

/* ===== SUBMIT SECTION ===== */
/* Download Section */
.download {
    background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
    padding: 6rem 0;
    position: relative;
    overflow: hidden;
}

.download::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at 20% 80%, rgba(255, 215, 0, 0.1) 0%, transparent 50%),
                radial-gradient(circle at 80% 20%, rgba(0, 123, 255, 0.1) 0%, transparent 50%);
    pointer-events: none;
}

.download-content {
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 6rem;
    align-items: center;
    margin-top: 3rem;
    position: relative;
    z-index: 1;
}

.download-info h3 {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    line-height: 1.2;
}

.download-info p {
    font-size: 1.3rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    line-height: 1.7;
}

.download-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    margin-bottom: 3rem;
}

.stat {
    text-align: center;
    padding: 2rem 1.5rem;
    background: var(--bg-secondary);
    border-radius: 16px;
    border: 1px solid var(--border-color);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.stat:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.stat-number {
    display: block;
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 1rem;
    color: var(--text-secondary);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.btn-download {
    display: inline-flex;
    align-items: center;
    gap: 1rem;
    padding: 1.5rem 3rem;
    background: linear-gradient(135deg, var(--primary-color) 0%, #ff6b35 100%);
    color: var(--text-white);
    border: none;
    border-radius: 16px;
    font-size: 1.2rem;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 8px 32px rgba(255, 215, 0, 0.3);
    position: relative;
    overflow: hidden;
}

.btn-download::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s;
}

.btn-download:hover::before {
    left: 100%;
}

.btn-download:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 48px rgba(255, 215, 0, 0.4);
}

.btn-download:active {
    transform: translateY(-2px);
}

.btn-icon {
    font-size: 1.5rem;
}

.download-note {
    margin-top: 2rem;
    font-size: 1rem;
    color: var(--text-secondary);
    font-style: italic;
    text-align: center;
}

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

.dataset-preview {
    background: var(--bg-secondary);
    border-radius: 20px;
    border: 1px solid var(--border-color);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    width: 100%;
    max-width: 400px;
}

.preview-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, #ff6b35 100%);
    color: var(--text-white);
    padding: 1.5rem 2rem;
    font-weight: 600;
    font-size: 1.1rem;
    text-align: center;
}

.preview-content {
    padding: 2rem;
}

.data-line {
    font-family: 'Courier New', monospace;
    font-size: 1rem;
    color: var(--text-primary);
    margin-bottom: 0.8rem;
    padding: 0.5rem 1rem;
    background: var(--bg-primary);
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
}

.data-line:last-child {
    text-align: center;
    color: var(--text-secondary);
    font-style: italic;
    border-left: none;
    background: transparent;
}

.submit {
    background: var(--bg-primary);
    padding: 6rem 0;
}

.submit-content {
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 6rem;
    align-items: center;
    margin-top: 3rem;
}

.submit-info h3 {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    line-height: 1.2;
}

.submit-info p {
    font-size: 1.3rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    line-height: 1.7;
}

.submit-steps {
    margin-bottom: 3rem;
}

.step {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    margin-bottom: 2rem;
    padding: 1.5rem;
    background: var(--bg-secondary);
    border-radius: var(--border-radius);
    transition: all 0.3s ease;
}

.step:hover {
    background: var(--bg-tertiary);
    transform: translateX(8px);
    box-shadow: var(--shadow-md);
}

.step-number {
    background: var(--bg-gradient);
    color: var(--text-white);
    width: 3rem;
    height: 3rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 800;
    font-size: 1.2rem;
    box-shadow: var(--shadow-md);
    flex-shrink: 0;
}

.step-text {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 1.1rem;
}

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

.github-flow {
    display: flex;
    align-items: center;
    gap: 2rem;
    background: var(--text-white);
    padding: 3rem;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-xl);
    border: 1px solid var(--border-color);
}

.flow-step {
    background: var(--bg-gradient);
    color: var(--text-white);
    padding: 1.5rem 2rem;
    border-radius: var(--border-radius);
    font-weight: 700;
    font-size: 1.1rem;
    text-align: center;
    min-width: 120px;
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
}

.flow-step:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.flow-arrow {
    font-size: 2rem;
    color: var(--primary-color);
    font-weight: 800;
}

/* ===== FOOTER ===== */
.footer {
    background: var(--bg-dark);
    color: white;
    padding: 3rem 0 1rem;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 700;
    font-size: 1.25rem;
}

.footer-links {
    display: flex;
    gap: 2rem;
}

.footer-links a {
    color: var(--text-light);
    text-decoration: none;
    transition: color 0.2s ease;
}

.footer-links a:hover {
    color: white;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid #374151;
    color: var(--text-light);
}

/* ===== MODAL ===== */
.submission-instructions {
    max-width: 100%;
    margin: 0 auto;
}

.welcome-section {
    text-align: center;
    margin-bottom: 2rem;
}

.welcome-section h3 {
    font-size: 1.8rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.steps-container h4 {
    color: var(--text-primary);
    margin-bottom: 1.5rem;
    text-align: center;
}

.step-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.step-card {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 12px;
    padding: 1.5rem;
    border: 1px solid rgba(255, 255, 255, 0.1);
    transition: all 0.3s ease;
}

.step-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.3);
}

.step-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 2rem;
    height: 2rem;
    background: var(--primary-color);
    color: white;
    border-radius: 50%;
    font-weight: bold;
    margin-bottom: 1rem;
}

.step-content h5 {
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.step-content p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.5;
}

.step-content code {
    background: rgba(255, 215, 0, 0.2);
    color: var(--primary-color);
    padding: 0.2rem 0.4rem;
    border-radius: 4px;
    font-family: 'Courier New', monospace;
}

/* ===== MODAL ===== */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 2000;
    backdrop-filter: blur(5px);
    overflow-y: auto;
    padding: 2rem;
    box-sizing: border-box;
}

.modal.show {
    display: flex;
    align-items: flex-start;
    justify-content: center;
    padding-top: 5vh;
}

.modal-content {
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    border-radius: 20px;
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.5);
    max-width: 800px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    animation: modalSlideIn 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
    border: 1px solid rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(20px);
    margin: 2rem auto;
    position: relative;
    z-index: 2001;
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 2rem 2rem 1rem 2rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    background: linear-gradient(90deg, rgba(99, 102, 241, 0.1) 0%, rgba(168, 85, 247, 0.1) 100%);
    border-radius: 20px 20px 0 0;
}

.modal-header h2 {
    font-size: 1.8rem;
    font-weight: 700;
    color: #ffffff;
    margin: 0;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.close-modal {
    background: rgba(255, 255, 255, 0.1);
    border: none;
    font-size: 1.8rem;
    cursor: pointer;
    color: #ffffff;
    padding: 0.5rem;
    border-radius: 50%;
    transition: all 0.3s ease;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(10px);
}

.close-modal:hover {
    background: rgba(255, 255, 255, 0.2);
    color: #ff6b6b;
    transform: scale(1.1);
}

.modal-body {
    padding: 2rem;
    color: #ffffff;
}

.auth-options {
    margin-bottom: 1.5rem;
}

.btn-google {
    background: var(--text-white);
    color: var(--text-primary);
    border: 2px solid var(--border-color);
    padding: 1rem 2rem;
    border-radius: var(--border-radius);
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
        display: flex;
    align-items: center;
    gap: 1rem;
    width: 100%;
    justify-content: center;
    box-shadow: var(--shadow-sm);
}

.btn-google:hover {
    background: var(--bg-secondary);
    border-color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-google svg {
    flex-shrink: 0;
}

.auth-note {
    color: var(--text-light);
    font-size: 0.9rem;
    margin: 0;
}

/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 1024px) {
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 4rem;
    }
    
    .hero-text {
        text-align: center;
    }
    
    .hero-title {
        font-size: 3.5rem;
    }
    
    .code-animation {
        min-width: 350px;
    }
    
    .download-content {
        grid-template-columns: 1fr;
        gap: 4rem;
        text-align: center;
    }
    
    .download-stats {
        grid-template-columns: repeat(3, 1fr);
        gap: 1.5rem;
    }
    
    .submit-content {
        grid-template-columns: 1fr;
        gap: 4rem;
        text-align: center;
    }
    
    .github-flow {
        flex-direction: column;
        gap: 1.5rem;
    }
    
    .flow-arrow {
        transform: rotate(90deg);
    }
}

@media (max-width: 768px) {
    .hero {
        padding: 4rem 0;
        min-height: 80vh;
    }
    
    .hero-content {
        padding: 0 1rem;
        gap: 3rem;
    }
    
    .hero-title {
        font-size: 2.8rem;
    }
    
    .hero-subtitle {
        font-size: 1.2rem;
    }
    
    .hero-actions {
        flex-direction: column;
        align-items: center;
        gap: 1rem;
    }
    
    .download-info h3 {
        font-size: 2.2rem;
    }
    
    .download-info p {
        font-size: 1.1rem;
    }
    
    .download-stats {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    
    .stat {
        padding: 1.5rem 1rem;
    }
    
    .stat-number {
        font-size: 2rem;
    }
    
    .btn-download {
        width: 100%;
        max-width: 300px;
        justify-content: center;
        padding: 1.2rem 2rem;
        font-size: 1.1rem;
    }
    
    .dataset-preview {
        max-width: 100%;
    }
    
    .btn-primary,
    .btn-secondary {
        width: 100%;
        max-width: 300px;
        justify-content: center;
    }
    
    .code-animation {
        min-width: 300px;
        padding: 2rem;
    }
    
    .leaderboard-header,
    .leaderboard-entry {
        grid-template-columns: 80px 1fr 100px 100px;
        gap: 1rem;
        padding: 1rem 1.5rem;
    }
    
    .leaderboard-header {
        font-size: 0.9rem;
    }
    
    .submit-info h3 {
        font-size: 2.2rem;
    }
    
    .submit-info p {
        font-size: 1.1rem;
    }
    
    .step {
        padding: 1rem;
        gap: 1rem;
    }
    
    .step-number {
        width: 2.5rem;
        height: 2.5rem;
        font-size: 1rem;
    }
    
    .github-flow {
        padding: 2rem;
        gap: 1rem;
    }
    
    .flow-step {
        padding: 1rem 1.5rem;
        min-width: 100px;
        font-size: 1rem;
    }
    
    .footer-content {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 0.5rem;
    }
    
    .hero {
        padding: 2rem 0;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .btn-primary,
    .btn-secondary {
        padding: 0.875rem 1.5rem;
        font-size: 1rem;
    }
}