#epub-reader-container {
    max-width: 800px;
    margin: 30px auto;
    border: 1px solid #dcdc9d; /* Soft border */
    box-shadow: 0 4px 15px rgba(0,0,0,0.08);
    background: #ffffff;
    padding: 15px;
    border-radius: 8px;
    display: block !important;
    clear: both;
}

#epub-viewer {
    width: 100% !important;
    height: 600px !important; /* Force a hard fixed height */
    min-height: 600px !important;
    background: #fdfdfd;
    border-bottom: 2px solid #f0f0f0;
    position: relative !important;
    overflow: hidden !important;
}

/* Ensure the dynamically generated iframe expands to fill our viewer */
#epub-viewer iframe {
    width: 100% !important;
    height: 100% !important;
    display: block !important;
}

#epub-controls {
    display: flex;
    justify-content: space-between;
    padding: 15px 5px 5px 5px;
    background: #fff;
}

.epub-btn {
    background-color: #23282d;
    color: white;
    border: none;
    padding: 12px 24px;
    cursor: pointer;
    border-radius: 4px;
    font-size: 14px;
    font-weight: 600;
    transition: background 0.15s ease-in-out;
}

.epub-btn:hover {
    background-color: #0073aa;
}