:root {
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --secondary-color: #ec4899;
    --accent-color: #f59e0b;
    --background-color: #ffffff;
    --surface-color: #f8fafc;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --shadow-light: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-medium: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-large: 0 10px 25px rgba(0, 0, 0, 0.15);
}

[data-theme="dark"] {
    --background-color: #0f172a;
    --surface-color: #1e293b;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --border-color: #334155;
    --shadow-light: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-medium: 0 4px 6px rgba(0, 0, 0, 0.3);
    --shadow-large: 0 10px 25px rgba(0, 0, 0, 0.4);
}

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

body {
    font-family: 'Poppins', sans-serif;
    background-color: var(--background-color);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Navigation */
.navbar {
    background-color: var(--surface-color);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-light);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo h1 {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 700;
    font-size: 1.5rem;
}

.nav-controls {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.theme-btn {
    background: none;
    border: 2px solid var(--border-color);
    border-radius: 50px;
    padding: 0.5rem 1rem;
    cursor: pointer;
    font-size: 1rem;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.theme-btn:hover {
    border-color: var(--primary-color);
    transform: scale(1.05);
}

.sun-icon, .moon-icon {
    transition: opacity 0.3s ease;
}

[data-theme="dark"] .sun-icon {
    opacity: 0;
}

[data-theme="light"] .moon-icon,
body:not([data-theme]) .moon-icon {
    opacity: 0;
}

.language-select {
    background-color: var(--surface-color);
    color: var(--text-primary);
    border: 2px solid var(--border-color);
    border-radius: 25px;
    padding: 0.5rem 1rem;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.3s ease;
}

.language-select:hover {
    border-color: var(--primary-color);
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 4rem 0;
    text-align: 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"><circle cx="50" cy="50" r="2" fill="rgba(255,255,255,0.1)"/></svg>') repeat;
    animation: float 20s infinite linear;
}

@keyframes float {
    0% { transform: translateY(0px) rotate(0deg); }
    100% { transform: translateY(-100px) rotate(360deg); }
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
    position: relative;
    z-index: 1;
}

.hero-subtitle {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    opacity: 0.9;
    position: relative;
    z-index: 1;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 3rem;
    margin-top: 2rem;
    position: relative;
    z-index: 1;
}

.stat {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 0.9rem;
    opacity: 0.8;
}

/* Registration Section */
.registration {
    padding: 4rem 0;
    background-color: var(--surface-color);
}

.registration-card {
    background-color: var(--background-color);
    border-radius: 20px;
    padding: 3rem;
    box-shadow: var(--shadow-large);
    max-width: 600px;
    margin: 0 auto;
    border: 1px solid var(--border-color);
}

.registration-card h3 {
    font-size: 2rem;
    margin-bottom: 1rem;
    text-align: center;
    color: var(--primary-color);
}

.registration-description {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.registration-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.form-group {
    display: flex;
    flex-direction: column;
}

.form-group label {
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

.form-group input {
    padding: 1rem;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    font-size: 1rem;
    transition: all 0.3s ease;
    background-color: var(--background-color);
    color: var(--text-primary);
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.checkbox-group {
    flex-direction: row;
    align-items: center;
    gap: 0.5rem;
}

.checkbox-label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
    font-size: 0.9rem;
}

.checkbox-label input[type="checkbox"] {
    width: 20px;
    height: 20px;
    margin: 0;
}

.error-message {
    color: #ef4444;
    font-size: 0.8rem;
    margin-top: 0.25rem;
    min-height: 1.2rem;
}

.submit-btn {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border: none;
    padding: 1rem 2rem;
    border-radius: 50px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 1rem;
}

.submit-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-large);
}

.submit-btn:active {
    transform: translateY(0);
}

/* About Section */
.about {
    padding: 4rem 0;
}

.about h3 {
    text-align: center;
    font-size: 2rem;
    margin-bottom: 3rem;
    color: var(--primary-color);
}

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

.feature {
    text-align: center;
    padding: 2rem;
    background-color: var(--surface-color);
    border-radius: 15px;
    border: 1px solid var(--border-color);
    transition: all 0.3s ease;
}

.feature:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
}

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

.feature h4 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.feature p {
    color: var(--text-secondary);
}

/* Footer */
footer {
    background-color: var(--surface-color);
    border-top: 1px solid var(--border-color);
    padding: 2rem 0;
    text-align: center;
    color: var(--text-secondary);
}

.footer-note {
    font-size: 0.8rem;
    margin-top: 1rem;
    font-style: italic;
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    z-index: 2000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(5px);
}

.modal-content {
    background-color: var(--background-color);
    margin: 10% auto;
    padding: 2rem;
    border-radius: 20px;
    width: 90%;
    max-width: 500px;
    text-align: center;
    position: relative;
    box-shadow: var(--shadow-large);
}

.close {
    position: absolute;
    right: 1rem;
    top: 1rem;
    font-size: 2rem;
    cursor: pointer;
    color: var(--text-secondary);
}

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

.success-icon {
    font-size: 4rem;
    margin-bottom: 1rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-stats {
        flex-direction: column;
        gap: 1rem;
    }
    
    .registration-card {
        padding: 2rem 1rem;
        margin: 0 20px;
    }
    
    .nav-container {
        flex-direction: column;
        gap: 1rem;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 1.5rem;
    }
    
    .registration-card {
        padding: 1.5rem 1rem;
    }
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.registration-card {
    animation: fadeInUp 0.8s ease-out;
}

.feature {
    animation: fadeInUp 0.8s ease-out;
}

.feature:nth-child(1) { animation-delay: 0.1s; }
.feature:nth-child(2) { animation-delay: 0.2s; }
.feature:nth-child(3) { animation-delay: 0.3s; }