.chapter-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1000px;
    margin: 2rem auto;
    padding: 0 1rem;
}

.chapter-title {
    margin: 0;
    font-size: 1.5rem;
    color: #fff;
}

.chapter-controls {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.chapter-number {
    font-size: 1rem;
    color: #ccc;
}

.chapter-controls select {
    background: #1e1e1e;
    color: #fff;
    border: 1px solid #333;
    padding: 0.4rem 0.6rem;
    border-radius: 6px;
}

.chapter-images {
    max-width: 900px;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
}

.chapter-image {
    width: 100%;
}

.chapter-navigation {
    display: flex;
    justify-content: space-between;
    max-width: 900px;
    margin: 2rem auto;
    padding: 0 1rem;
}

.nav-btn {
    background: #007dfc;
    color: #fff;
    padding: 0.6rem 1.2rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: bold;
    transition: background 0.2s ease;
}

.nav-btn:hover {
    background: #005bb5;
}

.nav-btn.disabled {
    background: #444;
    color: #888;
    pointer-events: none;
    cursor: not-allowed;
}

@media screen and (max-width: 600px) {
    .chapter-main{
        margin: 0;
        padding: 0;
    }
    .chapter-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .chapter-controls {
        margin-top: 1rem;
        width: 100%;
        justify-content: space-between;
    }
}