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

        :root {
            --primary-color: #3B82F6;
            --premium-color: #ffdf00;
        }

        body {
            font-family: Arial, sans-serif;
            background-color: #fdfdfd;
            color: #333;
        }

        a {
            text-decoration: none;
            color: inherit;
        }

        .container {
            width: 90%;
            max-width: 1200px;
            margin: 0 auto;
            padding: 20px;
            role="main"
        }

        .premium-banner {
            margin-top: -40px;
            background-color: var(--premium-color);
            color: #333;
            padding: 10px 20px;
            text-align: center;
            font-size: 1rem;
            margin-bottom: 10px;
        }

        .premium-banner a {
            color: #333;
            text-decoration: underline;
        }

        .hero-lessons {
            background: linear-gradient(to right, #007bff, #0056b3);
            color: #fff;
            padding: 40px 10px;
            margin-bottom: 20px;
            role="banner"
        }

        .hero-lessons-container {
            display: flex;
            align-items: center;
            justify-content: space-between;
            flex-wrap: wrap;
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 20px;
            gap: 40px;
        }

        .hero-lessons-image {
            flex: 1 1 300px;
            display: flex;
            justify-content: center;
        }

        .hero-lessons-image img {
            width: 80%;
            max-width: 400px;
            height: auto;
        }

        .hero-lessons-content {
            flex: 1 1 200px;
            max-width: 600px;
            margin: 0 auto;
        }

        .hero-lessons-content h1 {
            font-size: 2.8rem;
            margin-bottom: 20px;
        }

        .hero-lessons-content p {
            font-size: 1.2rem;
            max-width: 600px;
            margin: 0 auto 15px;
            line-height: 1.5;
        }

        .hero-lessons-content .new-lessons {
            font-size: 1rem;
            font-style: italic;
            max-width: 600px;
            margin: 0 auto 30px;
            line-height: 1.5;
        }

        .cta-button {
            background: var(--premium-color);
            color: #333;
            padding: 0.75rem 1.5rem;
            border-radius: 5px;
            text-decoration: none;
            font-weight: bold;
            border: none;
            cursor: pointer;
            transition: background-color 0.3s ease;
            role="button"
        }

        .cta-button:hover,
        .cta-button:focus {
            background-color: #ffc700;
            outline: 2px solid var(--premium-color);
        }

        .feed-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            background-color: #fff;
            color: #000;
            padding: 1rem;
            margin-bottom: 20px;
        }

        .feed-title {
            font-size: 1.5rem;
            margin: 0;
        }

        .sort-dropdown {
            position: relative;
        }

        .sort-dropdown select {
            background-color: #fff;
            color: #000;
            border: 1px solid #ccc;
            padding: 0.5rem 1.5rem 0.5rem 0.5rem;
            border-radius: 4px;
            font-size: 0.9rem;
            cursor: pointer;
            appearance: none;
            background-image: url('data:image/svg+xml;utf8,<svg fill="%23000" height="24" viewBox="0 0 24 24" width="24" xmlns="http://www.w3.org/2000/svg"><path d="M7 10l5 5 5-5z"/></svg>');
            background-repeat: no-repeat;
            background-position: right 0.5rem center;
            transition: border-color 0.3s ease;
        }

        .sort-dropdown select:focus {
            outline: none;
            border-color: #999;
        }

        .sort-dropdown select option {
            background-color: #fff;
        }

        .search-filter-wrapper {
            text-align: center;
            margin-bottom: 40px;
        }

        .search-form {
            display: flex;
            flex-wrap: wrap;
            justify-content: center;
            max-width: 600px;
            width: 100%;
            margin: 0 auto;
            gap: 0.5rem;
        }

        .search-input {
            flex: 1;
            min-width: 200px;
            padding: 1rem;
            border: 2px solid #8AB1B5;
            border-radius: 8px;
            font-size: 1rem;
            background-color: #fff;
        }

        .search-input:focus {
            outline: none;
            border-color: var(--primary-color);
            box-shadow: 0 0 5px rgba(59, 130, 246, 0.3);
        }

        .search-button {
            background: var(--primary-color);
            color: #fff;
            border: none;
            padding: 1rem 2rem;
            border-radius: 8px;
            cursor: pointer;
            font-size: 1rem;
            font-weight: 600;
            transition: background 0.3s, transform 0.2s;
        }

        .search-button:hover {
            background: #2563EB;
            transform: scale(1.05);
        }

        .clear-button {
            background: #999;
            color: #fff;
            border: none;
            padding: 1rem 2rem;
            border-radius: 8px;
            cursor: pointer;
            font-size: 1rem;
            font-weight: 600;
            transition: background 0.3s, transform 0.2s;
            display: none;
        }

        .clear-button:hover {
            background: #666;
            transform: scale(1.05);
        }

        .filter-links {
            margin-top: 1rem;
        }

        .filter-link {
            display: inline-block;
            background: #e6eef2;
            color: #333;
            padding: 0.5rem 1rem;
            border-radius: 4px;
            font-size: 0.9rem;
            margin: 0 5px;
            cursor: pointer;
            role="button"
        }

        .filter-link:hover,
        .filter-link:focus {
            background: #cbd5e1;
            outline: 2px solid var(--primary-color);
        }

        .filter-link.active {
            background: var(--primary-color);
            color: #fff;
        }

        .lessons-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
            gap: 20px;
        }

        .lessons-grid.sorting::after {
            content: "Sorting...";
            display: block;
            text-align: center;
            color: #666;
            font-size: 1rem;
            padding: 1rem;
            animation: fadeIn 0.3s ease;
        }

        .lesson-card {
            background: #fff;
            border-radius: 8px;
            box-shadow: 0 4px 10px rgba(0, 0, 0, 0.08);
            transition: transform 0.3s ease, opacity 0.3s ease;
            position: relative;
            opacity: 1;
        }

        .lesson-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
        }

        .lesson-card.sorting {
            opacity: 0.5;
            transform: translateY(0);
        }

        .lesson-thumbnail {
            border-radius: 8px 8px 0 0;
            overflow: hidden;
        }

        .lesson-thumbnail img {
            width: 100%;
            height: auto;
            object-fit: cover;
            loading="lazy"
        }

        .lesson-lock-overlay,
        .lesson-free-overlay {
            position: absolute;
            top: 10px;
            right: 10px;
            font-size: 0.8rem;
            font-weight: bold;
            padding: 5px 10px;
            border-radius: 3px;
            box-shadow: 0 2px 5px rgba(0, 0, 0, 0.15);
        }

        .lesson-lock-overlay {
            background-color: var(--premium-color);
            color: #333;
        }

        .lesson-lock-overlay::before {
            content: "\f023";
            font-family: "Font Awesome 5 Free";
            margin-right: 5px;
            font-weight: 900;
        }

        .lesson-free-overlay {
            background-color: #28a745;
            color: #fff;
        }

        .lesson-free-overlay::before {
            content: "\f00c";
            font-family: "Font Awesome 5 Free";
            margin-right: 5px;
            font-weight: 900;
        }

        .lesson-info {
            padding: 20px;
            display: flex;
            flex-direction: column;
        }

        .lesson-meta {
            font-size: 0.9rem;
            color: #666;
            margin-bottom: 1rem;
        }

        .lesson-description {
            font-size: 0.95rem;
            line-height: 1.4;
            flex-grow: 1;
            margin-bottom: 1rem;
        }

        .lesson-button {
            background-color: var(--primary-color);
            color: #fff;
            padding: 8px 12px;
            border-radius: 5px;
            font-size: 0.9rem;
            border: none;
            cursor: pointer;
            display: inline-block;
            margin-top: 10px;
            margin-left: auto;
            role="button"
        }

        .lesson-button:hover,
        .lesson-button:focus {
            background-color: #0056b3;
            outline: 2px solid var(--primary-color);
        }

        .lesson-button.locked {
            background-color: var(--premium-color);
            color: #333;
        }

        .lesson-button.locked:hover,
        .lesson-button.locked:focus {
            background-color: #ffc700;
            outline: 2px solid var(--premium-color);
        }

        .no-results {
            text-align: center;
            padding: 2rem;
            font-size: 1.2rem;
            color: #555;
        }

        .no-results a {
            color: var(--primary-color);
            font-weight: bold;
        }

        .no-results a:hover,
        .no-results a:focus {
            text-decoration: underline;
            outline: 2px solid var(--primary-color);
        }

        .cta-banner {
            background-color: #0f172a;
            color: #fff;
            text-align: center;
            padding: 2rem 1rem;
            margin-top: 40px;
        }

        .cta-banner h3 {
            margin-bottom: 0.5rem;
            font-size: 1.5rem;
        }

        .cta-banner p {
            font-size: 1rem;
            max-width: 600px;
            margin: 0 auto 1rem;
            line-height: 1.5;
        }

        .cta-button {
            background: var(--premium-color);
            color: #333;
            padding: 0.75rem 1.5rem;
            border-radius: 5px;
            text-decoration: none;
            font-weight: bold;
            border: none;
            cursor: pointer;
            transition: background-color 0.3s ease;
            role="button"
        }

        .cta-button:hover,
        .cta-button:focus {
            background-color: #ffc700;
            outline: 2px solid var(--premium-color);
        }

        .footer-bar {
            background-color: #e6eef2;
            text-align: center;
            padding: 1rem 0;
            margin-top: 40px;
        }

        .footer-link {
            color: #333;
            margin: 0 0.5rem;
            font-size: 0.9rem;
        }

        .footer-link:hover,
        .footer-link:focus {
            text-decoration: underline;
            outline: 2px solid #333;
        }

        .footer-separator {
            color: #999;
            margin: 0 0.5rem;
        }

        @media (max-width: 768px) {
            .hero-lessons {
                padding: 30px 10px;
                margin-bottom: 20px;
            }

            .hero-lessons-content h1 {
                font-size: 2rem;
            }

            .hero-lessons-content p {
                font-size: 1rem;
            }

            .hero-lessons-container {
                flex-direction: column;
                text-align: center;
            }

            .hero-lessons-image {
                width: 100%;
                max-width: 400px;
                margin: 0 auto 20px;
            }
        }

        @media (max-width: 480px) {
            .search-form {
                flex-direction: column;
                align-items: stretch;
            }

            .search-input,
            .search-button,
            .clear-button {
                width: 100%;
                margin-bottom: 0.5rem;
            }

            .search-button,
            .clear-button {
                padding: 0.8rem;
            }

            .feed-header {
                flex-direction: row;
                justify-content: space-between;
            }

            .feed-title {
                font-size: 1.2rem;
                margin-right: 0.5rem;
            }

            .sort-dropdown select {
                padding: 0.6rem 2rem 0.6rem 0.6rem;
                font-size: 0.9rem;
                min-width: 150px;
            }
        }

        @media (max-width: 320px) {
            .feed-title {
                font-size: 1rem;
            }

            .lesson-meta,
            .lesson-description {
                font-size: 0.8rem;
            }

            .lesson-button {
                padding: 6px 10px;
                font-size: 0.8rem;
            }
        }

        @keyframes fadeIn {
            from {
                opacity: 0;
            }
            to {
                opacity: 1;
            }
        }

        .auth-modal {
            display: none;
            position: fixed;
            z-index: 9999;
            left: 0;
            top: 0;
            width: 100%;
            height: 100%;
            overflow: auto;
            background-color: rgba(0, 0, 0, 0.5);
        }

        .auth-modal-content {
            background: #fff;
            margin: 15% auto;
            padding: 20px;
            border-radius: 8px;
            width: 80%;
            max-width: 400px;
            text-align: center;
            position: relative;
        }

        .auth-modal-content h2 {
            margin-bottom: 1rem;
        }

        .auth-modal-content p {
            margin-bottom: 1.5rem;
        }

        .auth-modal-content button {
            background: var(--primary-color);
            color: #fff;
            border: none;
            padding: 0.75rem 1.5rem;
            border-radius: 8px;
            cursor: pointer;
            font-size: 1rem;
            margin: 0 10px;
            transition: background 0.3s, transform 0.2s;
            role="button"
        }

        .auth-modal-content button:hover,
        .auth-modal-content button:focus {
            background: #2563EB;
            outline: 2px solid var(--primary-color);
        }

        .close {
            position: absolute;
            right: 15px;
            top: 10px;
            font-size: 28px;
            font-weight: bold;
            cursor: pointer;
            role="button"
        }

        .close:hover,
        .close:focus {
            color: #999;
            outline: 2px solid #999;
        }