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

body{
   font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
   background: 
        linear-gradient(45deg, #fceff0 25%, transparent 25%),
        linear-gradient(-45deg, #fceff0 25%, transparent 25%),
        linear-gradient(45deg, transparent 75%, #fceff0 75%),
        linear-gradient(-45deg, transparent 75%, #fceff0 75%);
    background-size: 60px 40px;
    background-position: 0 0, 0 20px, 20px -20px, -20px 0px;
}

.heading {
   padding: 160px 0 0;
   text-align: center;
}

.heading-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    gap: 4rem;
    align-items: center;
    text-align: center;
}

.badge {
    background-color: #feefef;
    color: var(--theme-clr);
    font-size: 0.9rem;
    font-weight: 650;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    border: 0.2px solid var(--theme-clr);
    border-radius: 20px;
    padding: 0px 8px;
    margin-bottom: 0.75rem;
}

.title {
    font-size: 3rem;
    font-weight: 750;
    line-height: 1.2;
    margin-bottom: 1rem;
    color: #2d3748;
}

.description {
    font-size: 1rem;
    color: #666;
    margin-bottom: 2rem;
    line-height: 1.6; 
}

.login-note{
    background-color: #fefce8;
    padding: 1rem 2rem;
    margin: 2rem auto;
    max-width: 500px;
    border: 1px solid #ffeaa7;
    color: #856404;
}


.container {
     max-width: 1300px;
    margin: 0 auto;
}

        .learning-materials-tag {
            display: inline-flex;
            align-items: center;
            background: rgba(244, 67, 54, 0.1);
            border: 1px solid #f44336;
            border-radius: 20px;
            padding: 8px 16px;
            margin-bottom: 20px;
            color: #f44336;
            font-size: 14px;
            font-weight: 500;
        }

        .learning-materials-tag::before {
            content: "📚";
            margin-right: 8px;
        }

        .main-title {
            font-size: 48px;
            font-weight: 700;
            color: #2c3e50;
            text-align: center;
            margin-bottom: 16px;
        }

        .subtitle {
            font-size: 18px;
            color: #7f8c8d;
            text-align: center;
            margin-bottom: 40px;
            line-height: 1.6;
        }

        .bundle-section {
            background: white;
            border-radius: 16px;
            padding: 40px;
            margin-bottom: 40px;
            box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
            text-align: center;
        }

        .bundle-title {
            font-size: 32px;
            font-weight: 700;
            color: #2c3e50;
            margin-bottom: 16px;
        }

        .bundle-description {
            font-size: 18px;
            color: #7f8c8d;
            margin-bottom: 12px;
        }

        .bundle-pricing {
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 16px;
            margin-bottom: 22px;
        }

        .original-price {
            font-size: 29px;
            color: #bdc3c7;
            text-decoration: line-through;
            font-weight: 500;
        }

        .sale-price {
            font-size: 38px;
            color: #e74c3c;
            font-weight: 700;
        }

        .savings-badge {
            background: #27ae60;
            color: white;
            padding: 8px 16px;
            border-radius: 20px;
            font-size: 14px;
            font-weight: 600;
        }

        .bundle-button {
            background: #e74c3c;
            color: white;
            border: none;
            padding: 16px 32px;
            border-radius: 8px;
            font-size: 18px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            display: inline-flex;
            align-items: center;
            gap: 8px;
        }

        .bundle-button:hover {
            background: #c0392b;
            transform: translateY(-2px);
        }

        .level-section {
            background: white;
            border-radius: 16px;
            overflow: hidden;
            margin-bottom: 40px;
            box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
        }

        .level-header {
            padding: 32px 40px;
            position: relative;
            color: white;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

    .level-header.hsk1 { background: #f39c12; }
    .level-header.hsk2 { background: #2980b9; }
    .level-header.hsk5 { background: #323882; }
    .level-header.hsk6 { background: #632d77; }
    .level-header.hsk3 { background: #ff4f37; }
    .level-header.hsk4 { background: #a93a30; }

        .level-info h2 {
            font-size: 36px;
            font-weight: 700;
            margin-bottom: 8px;
        }

        .level-info p {
            font-size: 18px;
            opacity: 0.9;
        }

        .books-available {
            background: rgba(255, 255, 255, 0.2);
            padding: 12px 20px;
            border-radius: 20px;
            font-size: 14px;
            font-weight: 600;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .books-grid {
            display: grid;
            grid-template-columns: 1fr 1fr 1fr 1fr;
            gap: 24px;
            padding: 40px;
        }

        .book-card {
            background: white;
            border-radius: 12px;
            padding: 24px;
            text-align: center;
            transition: all 0.3s ease;
            border: 1px solid #e74c3c;
            box-shadow: 0 12px 40px rgba(0, 0, 0, 0.15);
        }

        .book-card:hover {
            transform: translateY(-4px);
            border-color: #e74c3c;
        }

        .book-title {
            font-size: 18px;
            text-align: left;
            margin-left: 5px;
            font-weight: 500;
            color: #2c3e50;
            margin: 12px 20px 0;
        }

        .book-price {
            font-size: 25px;
            font-weight: 600;
            color: #e74c3c;
            margin: 0 20px 0;
            text-align: left;
        }

        .book-rating {
            display: flex;
            align-items: center;
            justify-content: left;
            gap: 4px;
            margin: 0 20px 0;
            
        }

        .stars {
            color: #f39c12;
            font-size: 16px;
        }

        .rating-text {
            font-size: 14px;
            color: #7f8c8d;
            margin-left: 4px;
        }

        .availability {
            font-size: 14px;
            color: #27ae60;
            display: flex;
            align-items: center;
            justify-content: left;
            gap: 4px;
            margin: 12px 20px 20px;
        }

        .availability::before {
            content: "✓";
            font-weight: bold;
        }

        .book-actions {
            display: flex;
            flex-direction: column;
            gap: 12px;
        }

        .buy-now-btn {
            background: #e74c3c;
            color: white;
            border: none;
            padding: 12px 24px;
            border-radius: 6px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 8px;
        }

        .buy-now-btn:hover {
            background: #c0392b;
        }

        .add-to-cart-btn {
            background: transparent;
            color: #e74c3c;
            border: 2px solid #e74c3c;
            padding: 12px 24px;
            border-radius: 6px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 8px;
        }

        .add-to-cart-btn:hover {
            background: #e74c3c;
            color: white;
        }


@media (max-width: 768px) {
    .books-grid {
        grid-template-columns: 1fr 1fr;
        padding: 20px;
        gap: 16px;
    }

    .bundle-section {
        margin: 10px;
        padding: 24px;
    }

    .main-title {
        font-size: 32px;
    }

    .level-header {
        padding: 20px;
        flex-direction: column;
        text-align: center;
        gap: 1rem;
    }

    .level-info h2 {
        font-size: 24px;
    }

    .book-card {
        padding: 16px;
    }

    .book-title {
        font-size: 14px;
        margin: 8px 12px 0;
    }

    .book-price {
        font-size: 18px;
        margin: 0 12px;
    }

    .book-rating {
        margin: 0 12px;
    }

    .availability {
        font-size: 12px;
        margin: 8px 12px;
    }

    .buy-now-btn,
    .add-to-cart-btn {
        font-size: 14px;
        padding: 10px 20px;
    }
}

@media (max-width: 450px) {
    .books-grid {
        grid-template-columns: 1fr;
    }

    .bundle-section {
        margin-bottom: 3rem;
        padding: 16px;
    }   
}