:root {
    --fb-primary: #0284c7;
    --fb-primary-hover: #0369a1;
    --fb-shadow-book: 0 15px 35px -5px rgba(0, 0, 0, 0.3), 0 0 0 1px rgba(0, 0, 0, 0.05);
    --fb-radius-full: 9999px;
    --fb-font-sans: 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;
}

/* Khung Flipbook chuẩn theo container box-wp */
.flipbook-app-container {
    position: relative;
    width: 100%;
    max-width: 100%;
    background: transparent !important;
    border: none !important;
    outline: none !important;
    box-shadow: none !important;
    font-family: var(--fb-font-sans);
    display: flex;
    flex-direction: column;
    align-items: center;
    user-select: none;
    margin: 10px auto 30px auto;
}

.flipbook-app-container:fullscreen {
    width: 100vw !important;
    height: 100vh !important;
    max-width: 100vw !important;
    background: #0f172a !important;
    margin: 0 !important;
    padding: 0 !important;
    justify-content: center;
}

.flipbook-app-container:-webkit-full-screen {
    width: 100vw !important;
    height: 100vh !important;
    max-width: 100vw !important;
    background: #0f172a !important;
    margin: 0 !important;
    padding: 0 !important;
    justify-content: center;
}

/* Main Flipbook Wrapper */
.flipbook-app-container .flipbook-wrapper {
    position: relative;
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1;
    padding: 0;
    margin: 0 auto;
}

.flipbook-app-container:fullscreen .flipbook-wrapper,
.flipbook-app-container:-webkit-full-screen .flipbook-wrapper {
    flex: 1;
    width: 100%;
    height: 100%;
}

/* Loading Overlay */
.flipbook-app-container .loading-overlay {
    position: absolute;
    inset: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(8px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 50;
    transition: opacity 0.4s ease, visibility 0.4s ease;
    border-radius: 8px;
}

.flipbook-app-container:fullscreen .loading-overlay {
    background: rgba(15, 23, 42, 0.95);
}

.flipbook-app-container .loading-overlay.hidden {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
}

.flipbook-app-container .loader-content {
    text-align: center;
    max-width: 320px;
    width: 90%;
}

.flipbook-app-container .spinner-ring {
    width: 44px;
    height: 44px;
    margin: 0 auto 14px;
    border: 3px solid rgba(2, 132, 199, 0.2);
    border-top-color: var(--fb-primary);
    border-radius: 50%;
    animation: fb-spin 1s linear infinite;
}

@keyframes fb-spin {
    to {
        transform: rotate(360deg);
    }
}

.flipbook-app-container .loader-content h3 {
    font-size: 1rem;
    font-weight: 600;
    color: #0f172a;
    margin-bottom: 4px;
}

.flipbook-app-container .loader-content p {
    font-size: 0.825rem;
    color: #64748b;
    margin-bottom: 12px;
}

.flipbook-app-container .progress-bar-container {
    height: 5px;
    background: rgba(0, 0, 0, 0.08);
    border-radius: var(--fb-radius-full);
    overflow: hidden;
}

.flipbook-app-container .progress-bar-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, #0284c7, #38bdf8);
    transition: width 0.2s ease;
}

/* Nút điều hướng chuyển trang Flipbook độc lập (fb-ctrl-btn) */
.flipbook-app-container .fb-ctrl-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 44px;
    height: 44px;
    border-radius: var(--fb-radius-full);
    background: rgba(15, 23, 42, 0.75);
    backdrop-filter: blur(8px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    cursor: pointer;
    z-index: 25;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 6px 14px rgba(0, 0, 0, 0.25);
    padding: 0;
    margin: 0;
    outline: none;
}

.flipbook-app-container .fb-ctrl-btn:hover {
    background: var(--fb-primary);
    transform: translateY(-50%) scale(1.1);
}

.flipbook-app-container .fb-ctrl-prev {
    left: 8px;
}

.flipbook-app-container .fb-ctrl-next {
    right: 8px;
}

.flipbook-app-container .fb-ctrl-prev::before {
    content: "";
    display: block;
    width: 10px;
    height: 10px;
    border-top: 2.5px solid #ffffff;
    border-left: 2.5px solid #ffffff;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-35%, -50%) rotate(-45deg);
}

.flipbook-app-container .fb-ctrl-next::before {
    content: "";
    display: block;
    width: 10px;
    height: 10px;
    border-top: 2.5px solid #ffffff;
    border-right: 2.5px solid #ffffff;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-65%, -50%) rotate(45deg);
}

/* Book Display Container */
.flipbook-app-container .book-container {
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto;
    transition: transform 0.2s ease-out;
    transform-origin: center center;
}

.flipbook-app-container .flipbook {
    box-shadow: var(--fb-shadow-book);
    border-radius: 4px;
    margin: 0 auto;
}

/* Page Items inside Flipbook */
.flipbook-app-container .page {
    background-color: #ffffff;
    box-shadow: 0 0 12px rgba(0, 0, 0, 0.12);
    overflow: hidden;
    border: none !important;
    outline: none !important;
}

.flipbook-app-container .page-content {
    width: 100%;
    height: 100%;
    display: block;
    position: relative;
    background-color: #ffffff;
}

.flipbook-app-container .page-content canvas {
    width: 100% !important;
    height: 100% !important;
    display: block;
}

/* Page Spine & Realistic Shadow */
.flipbook-app-container .page.--left {
    border-right: 1px solid rgba(0, 0, 0, 0.08);
}

.flipbook-app-container .page.--right {
    border-left: 1px solid rgba(0, 0, 0, 0.08);
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .flipbook-app-container {
        margin: 5px auto 20px auto;
    }

    .flipbook-app-container .fb-ctrl-btn {
        width: 36px;
        height: 36px;
        background: rgba(15, 23, 42, 0.7);
        border: 1px solid rgba(255, 255, 255, 0.25);
        z-index: 30;
    }

    .flipbook-app-container .fb-ctrl-prev {
        left: 4px;
    }

    .flipbook-app-container .fb-ctrl-next {
        right: 4px;
    }

    .flipbook-app-container .fb-ctrl-prev::before,
    .flipbook-app-container .fb-ctrl-next::before {
        width: 8px;
        height: 8px;
        border-width: 2px;
    }
}