:root {
            --primary-color: #212529;
            --secondary-color: #495057;
            --accent-color: #6c757d;
            --success-color: #28a745;
            --danger-color: #dc3545;
            --warning-color: #ffc107;
            --info-color: #17a2b8;
            --dark-color: #343a40;
            --light-color: #f8f9fa;
            --font-main: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
            --font-code: 'Times New Roman', Courier, monospace;
            --cyber-accent: #9a9b9b;
            --cyber-accent-dark: #626464;
        }

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

        body {
            font-family: var(--font-main);
            line-height: 1.6;
            background-color: var(--dark-color);
            color: var(--light-color);
            padding: 20px;
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            position: relative;
            overflow-x: hidden;
        }

        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 20px;
            background-color: rgba(25, 25, 25, 0.95);
            border-radius: 8px;
            box-shadow: 0 0 20px rgba(118, 121, 119, 0.1);
            position: relative;
            z-index: 1;
            flex: 1;
        }

        header {
            text-align: center;
            margin-bottom: 30px;
            border-bottom: 2px solid var(--cyber-accent);
            padding-bottom: 20px;
            position: relative;
        }

        header h1 {
            font-size: 2.5rem;
            color: var(--cyber-accent);
            margin-bottom: 10px;
            text-shadow: 0 0 10px rgba(183, 183, 183, 0.3);
        }

        header h2 {
            font-size: 1.5rem;
            color: var(--light-color);
            font-style: italic;
        }

        .cyber-grid {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background-image:
                linear-gradient(rgba(25, 25, 25, 0.98) 1px, transparent 1px),
                linear-gradient(90deg, rgba(25, 25, 25, 0.98) 1px, transparent 1px);
            background-size: 40px 40px;
            background-position: center center;
            z-index: -1;
            pointer-events: none;
        }

        .challenge-nav {
            display: flex;
            justify-content: center;
            margin-bottom: 30px;
            flex-wrap: wrap;
            gap: 10px;
        }

        .challenge-btn {
            background-color: var(--dark-color);
            color: var(--light-color);
            border: 1px solid var(--secondary-color);
            padding: 10px 15px;
            cursor: pointer;
            font-family: var(--font-main);
            font-size: 1rem;
            border-radius: 4px;
            transition: all 0.3s ease;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .challenge-btn.active {
            background-color: var(--cyber-accent-dark);
            color: var(--light-color);
            border-color: var(--cyber-accent);
        }

        .challenge-btn:hover {
            border-color: var(--cyber-accent);
            box-shadow: 0 0 10px rgba(0, 255, 140, 0.3);
        }

        .challenge-btn i {
            font-size: 1.1rem;
        }

        .challenge-status {
            width: 12px;
            height: 12px;
            border-radius: 50%;
            background-color: var(--secondary-color);
            display: inline-block;
        }

        .challenge-status.complete {
            background-color: var(--success-color);
        }

        .challenge-container {
            background-color: var(--dark-color);
            border: 1px solid var(--secondary-color);
            border-radius: 8px;
            padding: 25px;
            margin-bottom: 30px;
            position: relative;
            min-height: 400px;
        }

        .challenge-section {
            display: none;
        }

        .challenge-section.active {
            display: block;
            animation: fadeIn 0.5s ease;
        }

        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(10px); }
            to { opacity: 1; transform: translateY(0); }
        }

        .challenge-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 20px;
            padding-bottom: 15px;
            border-bottom: 1px dashed var(--secondary-color);
        }

        .challenge-title {
            font-size: 1.5rem;
            color: var(--cyber-accent);
        }

        .challenge-difficulty {
            background-color: var(--dark-color);
            color: var(--light-color);
            padding: 5px 10px;
            border-radius: 4px;
            font-size: 0.9rem;
            display: flex;
            align-items: center;
            gap: 5px;
        }

        .challenge-difficulty[data-level="easy"] {
            border: 1px solid var(--success-color);
        }

        .challenge-difficulty[data-level="medium"] {
            border: 1px solid var(--warning-color);
        }

        .challenge-difficulty[data-level="hard"] {
            border: 1px solid var(--danger-color);
        }

        .challenge-description {
            margin-bottom: 25px;
            font-size: 1.1rem;
            line-height: 1.6;
        }

        .code-block {
            background-color: #1a1a1a;
            color: #f0f0f0;
            padding: 15px;
            border-radius: 4px;
            font-family: var(--font-code);
            margin: 15px 0;
            overflow-x: auto;
            position: relative;
            border-left: 3px solid var(--cyber-accent);
        }

        .code-block pre {
            white-space: pre-wrap;
            font-size: 0.9rem;
            line-height: 1.4;
        }

        .code-block-header {
            background-color: #252525;
            padding: 5px 15px;
            border-top-left-radius: 4px;
            border-top-right-radius: 4px;
            font-size: 0.9rem;
            color: #aaa;
            margin: -15px -15px 15px -15px;
            display: flex;
            justify-content: space-between;
        }

        .code-block-header .filename {
            font-weight: bold;
        }

        .flag-input-container {
            margin-top: 30px;
        }

        .flag-input {
            display: flex;
            gap: 10px;
        }

        .flag-input input {
            flex: 1;
            padding: 12px 15px;
            background-color: #1a1a1a;
            border: 1px solid var(--secondary-color);
            color: var(--light-color);
            font-family: var(--font-code);
            border-radius: 4px;
            font-size: 1rem;
        }

        .flag-input input:focus {
            outline: none;
            border-color: var(--cyber-accent);
            box-shadow: 0 0 10px rgba(0, 255, 140, 0.3);
        }

        .flag-input button {
            padding: 12px 25px;
            background-color: var(--cyber-accent-dark);
            color: var(--light-color);
            border: none;
            border-radius: 4px;
            cursor: pointer;
            font-family: var(--font-main);
            font-size: 1rem;
            transition: all 0.3s ease;
        }

        .flag-input button:hover {
            background-color: var(--cyber-accent);
            color: var(--dark-color);
        }

        .flag-result {
            margin-top: 15px;
            padding: 12px;
            border-radius: 4px;
            font-weight: bold;
            display: none;
        }

        .flag-result.success {
            background-color: rgba(40, 167, 69, 0.2);
            border: 1px solid var(--success-color);
            color: var(--success-color);
            display: block;
        }

        .flag-result.error {
            background-color: rgba(220, 53, 69, 0.2);
            border: 1px solid var(--danger-color);
            color: var(--danger-color);
            display: block;
        }

        .hint-container {
            margin-top: 30px;
            border-top: 1px dashed var(--secondary-color);
            padding-top: 20px;
        }

        .hint-btn {
            background-color: transparent;
            color: var(--info-color);
            border: 1px solid var(--info-color);
            padding: 8px 15px;
            cursor: pointer;
            font-family: var(--font-main);
            font-size: 0.9rem;
            border-radius: 4px;
            transition: all 0.3s ease;
        }

        .hint-btn:hover {
            background-color: rgba(23, 162, 184, 0.1);
        }

        .hint-content {
            margin-top: 15px;
            padding: 15px;
            background-color: rgba(23, 162, 184, 0.1);
            border-left: 3px solid var(--info-color);
            border-radius: 4px;
            display: none;
        }

        .hint-content.visible {
            display: block;
            animation: fadeIn 0.5s ease;
        }

        .progress-container {
            margin-bottom: 30px;
        }

        .progress-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 10px;
        }

        .progress-title {
            font-size: 1.2rem;
            color: var(--light-color);
        }

        .progress-score {
            font-size: 1.2rem;
            color: var(--cyber-accent);
            font-weight: bold;
        }

        .progress-bar {
            width: 100%;
            height: 10px;
            background-color: #1a1a1a;
            border-radius: 5px;
            overflow: hidden;
        }

        .progress-fill {
            height: 100%;
            background-color: var(--cyber-accent);
            width: 0%;
            transition: width 0.5s ease;
        }

        .resource-section {
            margin-top: 40px;
            padding-top: 20px;
            border-top: 2px solid var(--secondary-color);
        }

        .resource-section h3 {
            font-size: 1.3rem;
            color: var(--light-color);
            margin-bottom: 15px;
        }

        .resources-list {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
            gap: 15px;
        }

        .resource-item {
            padding: 15px;
            background-color: #1a1a1a;
            border-radius: 4px;
            border-left: 3px solid var(--cyber-accent);
        }

        .resource-item h4 {
            font-size: 1.1rem;
            color: var(--cyber-accent);
            margin-bottom: 8px;
        }

        .resource-item p {
            font-size: 0.9rem;
            color: #ddd;
            margin-bottom: 10px;
        }

        .resource-item a {
            color: var(--info-color);
            text-decoration: none;
            font-size: 0.9rem;
            display: inline-flex;
            align-items: center;
            gap: 5px;
        }

        .resource-item a:hover {
            text-decoration: underline;
        }

        /* Badge notification for completed challenges */
        .badge-notification {
            position: fixed;
            top: 30px;
            right: 30px;
            background-color: var(--dark-color);
            border: 2px solid var(--cyber-accent);
            color: var(--light-color);
            padding: 15px 25px;
            border-radius: 8px;
            font-family: var(--font-main);
            z-index: 9999;
            display: flex;
            align-items: center;
            gap: 15px;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);
            transform: translateX(200%);
            transition: transform 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275);
            max-width: 350px;
        }

        .badge-notification.visible {
            transform: translateX(0);
        }

        .badge-icon {
            font-size: 2rem;
            color: var(--cyber-accent);
        }

        .badge-content h3 {
            font-size: 1.2rem;
            color: var(--cyber-accent);
            margin-bottom: 5px;
        }

        .badge-content p {
            font-size: 0.9rem;
        }

        /* Profile section */
        .profile-section {
            margin-top: 40px;
            padding: 20px;
            background-color: #1a1a1a;
            border-radius: 8px;
            border: 1px solid var(--secondary-color);
        }

        .profile-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 20px;
            padding-bottom: 15px;
            border-bottom: 1px dashed var(--secondary-color);
        }

        .profile-title {
            font-size: 1.3rem;
            color: var(--light-color);
        }

        .profile-badges {
            display: flex;
            flex-wrap: wrap;
            gap: 15px;
            margin-top: 20px;
        }

        .profile-badge {
            background-color: #252525;
            border-radius: 8px;
            padding: 15px;
            display: flex;
            flex-direction: column;
            align-items: center;
            width: 120px;
            text-align: center;
            border: 1px solid var(--secondary-color);
            transition: all 0.3s ease;
        }

        .profile-badge.locked {
            opacity: 0.5;
            filter: grayscale(1);
        }

        .profile-badge:hover {
            border-color: var(--cyber-accent);
            box-shadow: 0 0 10px rgba(0, 255, 140, 0.2);
        }

        .badge-icon-large {
            font-size: 2.5rem;
            color: var(--cyber-accent);
            margin-bottom: 10px;
        }

        .badge-name {
            font-size: 0.9rem;
            font-weight: bold;
            color: var(--light-color);
            margin-bottom: 5px;
        }

        .badge-desc {
            font-size: 0.8rem;
            color: #aaa;
        }
        /* Header styles */
        header {
            background-color: var(--primary-color);
            color: white;
            padding: 15px 0;
            position: sticky;
            top: 0;
            z-index: 1000;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
            border-bottom: 1px solid rgba(255, 255, 255, 0.1);
        }

        header:after {
            content: "";
            position: absolute;
            bottom: -5px;
            left: 0;
            width: 100%;
            height: 5px;
            background: linear-gradient(to right, transparent, rgba(255, 255, 255, 0.1), transparent);
        }

        nav {
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        .logo {
            font-size: 24px;
            font-weight: bold;
            display: flex;
            align-items: center;
        }

        .logo i {
            margin-right: 10px;
            color: #adb5bd;
        }

        .nav-links {
            display: flex;
            list-style: none;
        }

        .nav-links li {
            margin-left: 30px;
        }

        .nav-links a {
            color: white;
            font-weight: 500;
            position: relative;
            text-decoration: none;
        }

        .nav-links a:after {
            content: '';
            position: absolute;
            bottom: -5px;
            left: 0;
            width: 0;
            height: 1px;
            background-color: white;
            transition: width 0.3s;
        }

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

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

        .mobile-menu-btn {
            display: none;
            cursor: pointer;
            font-size: 24px;
        }

        .footer {
            margin-top: 50px;
            text-align: center;
            color: #888;
            font-size: 0.9rem;
        }
        /* Footer */
        footer {
            background-color: var(--dark-bg);
            color: white;
            padding: 60px 0 30px;
            margin-top: 60px;
        }

        .footer-content {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 50px;
            margin-bottom: 40px;
        }

        .footer-about h3 {
            font-size: 24px;
            margin-bottom: 20px;
            color: white;
        }

        .footer-about p {
            margin-bottom: 20px;
            opacity: 0.8;
            line-height: 1.7;
        }

        .social-links {
            display: flex;
            gap: 15px;
        }

        .social-link {
            width: 40px;
            height: 40px;
            background-color: rgba(255, 255, 255, 0.1);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            color: white;
            transition: background-color 0.3s;
        }

        .social-link:hover {
            background-color: rgba(255, 255, 255, 0.2);
            color: white;
        }

        .footer-links h3 {
            font-size: 24px;
            margin-bottom: 20px;
            color: white;
        }

        .quick-links {
            list-style: none;
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 15px;
        }

        .quick-links a {
            color: rgba(255, 255, 255, 0.8);
            transition: color 0.3s;
            display: flex;
            align-items: center;
            text-decoration: none;
        }

        .quick-links a:hover {
            color: var(--accent-color);
        }

        .quick-links a i {
            margin-right: 10px;
            font-size: 14px;
        }

        .copyright {
            text-align: center;
            padding-top: 30px;
            border-top: 1px solid rgba(255, 255, 255, 0.1);
            font-size: 14px;
            opacity: 0.7;
        }

        /* Responsive styles */
        @media (max-width: 768px) {
            .container {
                padding: 15px;
            }

            header h1 {
                font-size: 2rem;
            }

            header h2 {
                font-size: 1.3rem;
            }

            .challenge-container {
                padding: 15px;
            }

            .challenge-header {
                flex-direction: column;
                align-items: flex-start;
                gap: 10px;
            }

            .resources-list {
                grid-template-columns: repeat(auto-fill, minmax(100%, 1fr));
            }

            .flag-input {
                flex-direction: column;
            }

            .profile-badges {
                justify-content: center;
            }

            .challenge-nav {
                flex-direction: column;
                align-items: stretch;
            }
            .mobile-menu-btn {
                display: block;
            }

            .nav-links {
                position: fixed;
                top: 70px;
                left: 0;
                width: 100%;
                flex-direction: column;
                background-color: var(--primary-color);
                padding: 20px;
                transform: translateY(-150%);
                transition: transform 0.3s;
                z-index: 1000;
            }

            .nav-links.active {
                transform: translateY(0);
            }

            .nav-links li {
                margin: 15px 0;
            }
        }