/* Mobile First Approach */
@media (max-width: 768px) {
    .header .container {
        padding: 0 15px;
    }

    .main-nav {
        position: fixed;
        top: var(--header-height);
        left: -100%;
        width: 100%;
        height: calc(100vh - var(--header-height));
        background-color: var(--white);
        transition: left 0.3s ease;
    }

    .main-nav.active {
        left: 0;
    }

    .main-nav ul {
        flex-direction: column;
        padding: 20px;
    }

    .main-nav li {
        margin: 10px 0;
    }

    .mobile-menu-btn {
        display: block;
    }

    .mobile-menu-btn.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .mobile-menu-btn.active span:nth-child(2) {
        opacity: 0;
    }

    .mobile-menu-btn.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -6px);
    }

    .hero h1 {
        font-size: 2.5rem;
    }

    .hero-description {
        font-size: 1rem;
    }

    .chapters-grid {
        grid-template-columns: 1fr;
    }

    .chapter-card img {
        height: 300px;
    }
}

/* Tablet Styles */
@media (min-width: 769px) and (max-width: 1024px) {
    .chapters-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Large Desktop Styles */
@media (min-width: 1025px) {
    .container {
        padding: 0 40px;
    }
}