:root {
    --primary: #00ff41;
    --primary-dark: #00cc34;
    --primary-glow: rgba(0, 255, 65, 0.3);
    --bg-dark: #0a0a0a;
    --bg-card: #111111;
    --bg-hover: #1a1a1a;
    --text: #e0e0e0;
    --text-dim: #888888;
    --border: #222222;
    --danger: #ff4444;
    --warning: #ffaa00;
    --success: #00ff41;
}

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

body {
    font-family: 'Inter', sans-serif;
    background: var(--bg-dark);
    color: var(--text);
    line-height: 1.6;
}

.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(10, 10, 10, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
    z-index: 1000;
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
}

.nav-logo i {
    font-size: 1.8rem;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 2rem;
}

.nav-link {
    color: var(--text);
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-link:hover {
    color: var(--primary);
    background: var(--bg-hover);
}

.nav-link.active {
    color: var(--primary);
    background: rgba(0, 255, 65, 0.1);
}

.btn-register {
    background: var(--primary);
    color: #000 !important;
}

.btn-register:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 20px var(--primary-glow);
}

.user-dropdown {
    position: relative;
    display: flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
    padding: 0.5rem 1rem;
    border-radius: 8px;
}

.user-dropdown:hover {
    background: var(--bg-hover);
}

.user-avatar {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    object-fit: cover;
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    right: 0;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 0.5rem 0;
    min-width: 150px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all 0.3s ease;
}

.user-dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-menu a {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 0.75rem 1rem;
    color: var(--text);
    text-decoration: none;
}

.dropdown-menu a:hover {
    background: var(--bg-hover);
    color: var(--primary);
}

.menu-toggle {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--primary);
}

.main-content {
    margin-top: 80px;
    min-height: calc(100vh - 200px);
    padding: 2rem;
    max-width: 1400px;
    margin-left: auto;
    margin-right: auto;
}

.hero {
    text-align: center;
    padding: 4rem 2rem;
    background: linear-gradient(135deg, rgba(0, 255, 65, 0.05) 0%, rgba(0, 0, 0, 0) 100%);
    border-radius: 20px;
    margin-bottom: 3rem;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    margin-bottom: 1rem;
}

.hero p {
    font-size: 1.2rem;
    color: var(--text-dim);
    max-width: 600px;
    margin: 0 auto;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.stat-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 1.5rem;
    text-align: center;
    transition: all 0.3s ease;
}

.stat-card:hover {
    transform: translateY(-5px);
    border-color: var(--primary);
    box-shadow: 0 10px 30px rgba(0, 255, 65, 0.1);
}

.stat-card i {
    font-size: 2.5rem;
    color: var(--primary);
    margin-bottom: 1rem;
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--primary);
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.challenges-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 1.5rem;
}

.challenge-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 16px;
    overflow: hidden;
    transition: all 0.3s ease;
    cursor: pointer;
}

.challenge-card:hover {
    transform: translateY(-5px);
    border-color: var(--primary);
    box-shadow: 0 10px 30px rgba(0, 255, 65, 0.1);
}

.challenge-header {
    padding: 1rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border);
    background: linear-gradient(135deg, rgba(0, 255, 65, 0.1) 0%, rgba(0, 0, 0, 0) 100%);
}

.challenge-category {
    font-size: 0.8rem;
    padding: 0.25rem 0.75rem;
    background: rgba(0, 255, 65, 0.1);
    border-radius: 20px;
    color: var(--primary);
}

.challenge-points {
    font-weight: 700;
    color: var(--primary);
}

.challenge-body {
    padding: 1.5rem;
}

.challenge-title {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.challenge-description {
    color: var(--text-dim);
    font-size: 0.9rem;
    margin-bottom: 1rem;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.challenge-footer {
    padding: 1rem 1.5rem;
    background: var(--bg-hover);
    border-top: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
}

.leaderboard-table {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 16px;
    overflow: hidden;
}

.leaderboard-table table {
    width: 100%;
    border-collapse: collapse;
}

.leaderboard-table th,
.leaderboard-table td {
    padding: 1rem;
    text-align: left;
    border-bottom: 1px solid var(--border);
}

.leaderboard-table th {
    background: var(--bg-hover);
    color: var(--primary);
}

.rank-1 { color: #ffd700; font-weight: 700; }
.rank-2 { color: #c0c0c0; font-weight: 700; }
.rank-3 { color: #cd7f32; font-weight: 700; }

.card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 2rem;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--text-dim);
    font-size: 0.9rem;
}

.form-group input,
.form-group textarea,
.form-group select {
    width: 100%;
    padding: 0.75rem 1rem;
    background: var(--bg-hover);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text);
    font-family: inherit;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary);
}

.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn-primary {
    background: var(--primary);
    color: #000;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 20px var(--primary-glow);
}

.toast {
    position: fixed;
    top: 80px;
    right: 20px;
    padding: 1rem 1.5rem;
    border-radius: 8px;
    display: flex;
    align-items: center;
    gap: 10px;
    z-index: 1100;
    animation: slideIn 0.3s ease;
}

.toast-success {
    background: rgba(0, 255, 65, 0.2);
    border: 1px solid var(--primary);
    color: var(--primary);
}

.toast-error {
    background: rgba(255, 68, 68, 0.2);
    border: 1px solid var(--danger);
    color: var(--danger);
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

.footer {
    background: var(--bg-card);
    border-top: 1px solid var(--border);
    padding: 3rem 2rem 1rem;
    margin-top: 3rem;
}

.footer-container {
    max-width: 1400px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.footer-section h4 {
    color: var(--primary);
    margin-bottom: 1rem;
}

.footer-section a {
    display: block;
    color: var(--text-dim);
    text-decoration: none;
    margin-bottom: 0.5rem;
    transition: all 0.3s ease;
}

.footer-section a:hover {
    color: var(--primary);
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    margin-top: 2rem;
    border-top: 1px solid var(--border);
    color: var(--text-dim);
    font-size: 0.8rem;
}

@media (max-width: 768px) {
    .menu-toggle {
        display: block;
    }
    
    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 100%;
        height: calc(100vh - 70px);
        background: var(--bg-dark);
        flex-direction: column;
        padding: 2rem;
        transition: left 0.3s ease;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .hero h1 {
        font-size: 2rem;
    }
    
    .challenges-grid {
        grid-template-columns: 1fr;
    }
}