body {
    margin: 0;
    padding: 0;
    font-family: 'Poppins', sans-serif;
    background: linear-gradient(135deg, #6a11cb, #2575fc);
    background-attachment: fixed;
    background-size: cover;
    color: white;
    overflow-x: hidden;
    min-height: 100vh;
}

.grammar-detail-container {
    max-width: 1000px;
    margin: 60px auto;
    padding: 40px;
    background: rgba(255, 255, 255, 0.08);
    border-radius: 20px;
    border: 1px solid rgba(255, 255, 255, 0.15);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.4),
                0 0 0 5px rgba(255, 255, 255, 0.05);
    text-align: center;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    color: #f0f0f0;
    position: relative;
    overflow: hidden;
}

.grammar-detail-container::before {
    content: '';
    position: absolute;
    top: -2px; bottom: -2px; left: -2px; right: -2px;
    background: linear-gradient(135deg, #ffda47 0%, #2575fc 100%);
    z-index: -1;
    border-radius: 22px;
    filter: blur(8px);
    opacity: 0;
    transition: opacity 0.5s ease-in-out;
}

.grammar-detail-container:hover::before {
    opacity: 0.2;
}

.grammar-detail-container h1 {
    font-family: 'Poppins', sans-serif;
    font-size: 3.8rem;
    color: #ffda47;
    margin-bottom: 25px;
    text-shadow: 0 0 20px rgba(255, 255, 255, 0.5), 0 0 8px rgba(0, 0, 0, 0.6);
    letter-spacing: 2px;
    padding-bottom: 20px;
    border-bottom: 2px solid rgba(255, 255, 255, 0.1);
}

.intro-text {
    font-family: 'Montserrat', sans-serif;
    font-size: 1.25rem;
    margin-bottom: 60px;
    opacity: 0.8;
    line-height: 1.8;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
    color: rgba(255, 255, 255, 0.9);
}

.main-categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
    margin-top: 40px;
    padding: 20px;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 18px;
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.25), inset 0 0 15px rgba(255, 255, 255, 0.08);
}

.category-card {
    display: block;
    background: rgba(255, 255, 255, 0.08);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 15px;
    padding: 25px;
    text-align: left;
    text-decoration: none;
    color: #f0f0f0;
    transition: transform 0.3s ease, background 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
}

.category-card:hover {
    transform: translateY(-8px);
    background: rgba(255, 255, 255, 0.15);
    border-color: #ffda47;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.35);
}

.category-card h3 {
    font-family: 'Poppins', sans-serif;
    font-size: 1.8rem;
    color: #ffda47;
    margin-top: 0;
    margin-bottom: 15px;
    text-shadow: 0 0 8px rgba(255, 255, 255, 0.3);
}

.category-card p {
    font-family: 'Montserrat', sans-serif;
    font-size: 1rem;
    opacity: 0.9;
    line-height: 1.6;
}

.navigation-links {
    margin-top: 60px;
    text-align: center;
}

.back-to-list-btn {
    display: inline-flex;
    align-items: center;
    background-color: #ffda47;``
    color: #6a11cb;
    padding: 16px 35px;
    border-radius: 10px;
    text-decoration: none;
    font-weight: bold;
    font-size: 1.2rem;
    transition: background-color 0.3s ease, color 0.3s ease, transform 0.3s ease, box-shadow 0.3s ease;
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.25);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.back-to-list-btn i {
    margin-right: 15px;
    font-size: 1.1em;
}

.back-to-list-btn:hover {
    background-color: #e6b800;
    color: #fff;
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
}

@media (max-width: 768px) {
    .grammar-detail-container {
        margin: 30px 15px;
        padding: 25px;
        border-radius: 15px;
    }
    .grammar-detail-container h1 {
        font-size: 2.8rem;
        letter-spacing: 1px;
    }
    .intro-text {
        font-size: 1.05rem;
        margin-bottom: 30px;
    }
    .main-categories-grid {
        gap: 20px;
        padding: 15px;
    }
    .category-card {
        padding: 20px;
    }
    .category-card h3 {
        font-size: 1.5rem;
    }
    .back-to-list-btn {
        padding: 12px 25px;
        font-size: 1rem;
    }
}

.secondary-navbar {
    background: rgba(255, 255, 255, 0.1);
    padding: 10px 0;
    margin-top: 70px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(5px);
}

.secondary-nav-container {
    display: flex;
    justify-content: center;
    gap: 30px;
    max-width: 1200px;
    margin: 0 auto;
}

.secondary-nav-link {
    color: white;
    text-decoration: none;
    font-size: 1rem;
    font-weight: 500;
    padding: 8px 16px;
    border-radius: 5px;
    transition: background 0.3s ease;
    display: flex;
    align-items: center;
    gap: 8px;
}

.secondary-nav-link.active {
    background: rgba(255, 255, 255, 0.2);
    border-bottom: 2px solid #ffcc00;
}

.secondary-nav-link.disabled {
    color: rgba(255, 255, 255, 0.5);
    cursor: not-allowed;
}

.secondary-nav-link i {
    font-size: 0.9rem;
}

.breadcrumbs {
    margin-bottom: 15px;
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.7);
}

.breadcrumbs a {
    color: white;
    text-decoration: none;
    transition: opacity 0.3s;
}

.breadcrumbs a:hover {
    opacity: 0.8;
}