/* =====================================================
   FSE Digital Flipbook — Stylesheet
   ===================================================== */

/* --- CSS Variables / Theme --- */
:root {
    --toolbar-bg: #1a1a2e;
    --toolbar-text: #e0e0e0;
    --toolbar-hover: #16213e;
    --toolbar-active: #0f3460;
    --accent: #e94560;
    --accent-hover: #c73e54;
    --sidebar-bg: #f5f5f7;
    --sidebar-width: 240px;
    --viewer-bg: #e8e8e8;
    --page-bg: #ffffff;
    --page-shadow: rgba(0, 0, 0, 0.25);
    --modal-overlay: rgba(0, 0, 0, 0.6);
    --border-radius: 8px;
    --transition-speed: 0.3s;
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
}

/* --- Reset & Base --- */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html, body {
    height: 100%;
    overflow: hidden;
    font-family: var(--font-family);
    background: var(--viewer-bg);
    color: #333;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.hidden {
    display: none !important;
}

/* --- Loading Screen --- */
#loading-screen {
    position: fixed;
    inset: 0;
    z-index: 10000;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 50%, #0f3460 100%);
    color: #fff;
}

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

.loader-spinner {
    width: 48px;
    height: 48px;
    border: 4px solid rgba(255, 255, 255, 0.2);
    border-top-color: var(--accent);
    border-radius: 50%;
    margin: 0 auto 20px;
    animation: spin 0.8s linear infinite;
}

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

.loader-text {
    font-size: 16px;
    margin-bottom: 16px;
    opacity: 0.9;
}

.loader-progress {
    width: 100%;
    height: 4px;
    background: rgba(255, 255, 255, 0.15);
    border-radius: 2px;
    overflow: hidden;
    margin-bottom: 8px;
}

.loader-progress-bar {
    height: 100%;
    width: 0%;
    background: var(--accent);
    border-radius: 2px;
    transition: width 0.3s ease;
}

.loader-percent {
    font-size: 13px;
    opacity: 0.7;
}

/* --- App Layout --- */
.app {
    display: flex;
    flex-direction: column;
    height: 100vh;
    height: 100dvh;
}

/* --- Toolbar --- */
.toolbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: relative;
    height: 48px;
    padding: 0 12px;
    background: var(--toolbar-bg);
    color: var(--toolbar-text);
    flex-shrink: 0;
    z-index: 100;
    user-select: none;
    gap: 8px;
}

.toolbar-left, .toolbar-center, .toolbar-right {
    display: flex;
    align-items: center;
    gap: 4px;
}

.toolbar-left {
    min-width: 0;
    flex: 0 1 auto;
}

.toolbar-center {
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    flex: 0 0 auto;
}

.toolbar-right {
    flex: 0 1 auto;
    justify-content: flex-end;
}

.toolbar-title {
    font-size: 14px;
    font-weight: 600;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    max-width: 200px;
    margin-left: 4px;
}

.toolbar-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border: none;
    background: transparent;
    color: var(--toolbar-text);
    cursor: pointer;
    border-radius: 6px;
    transition: background var(--transition-speed), color var(--transition-speed);
    flex-shrink: 0;
}

.toolbar-btn:hover {
    background: var(--toolbar-hover);
    color: #fff;
}

.toolbar-btn:active {
    background: var(--toolbar-active);
}

.toolbar-btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

.toolbar-divider {
    width: 1px;
    height: 24px;
    background: rgba(255, 255, 255, 0.15);
    margin: 0 4px;
    flex-shrink: 0;
}

/* Page Indicator */
.page-indicator {
    display: flex;
    align-items: center;
    gap: 4px;
    font-size: 13px;
    color: var(--toolbar-text);
}

.page-input {
    width: 42px;
    height: 28px;
    text-align: center;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 4px;
    color: #fff;
    font-size: 13px;
    font-family: inherit;
    outline: none;
    -moz-appearance: textfield;
}

.page-input::-webkit-inner-spin-button,
.page-input::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

.page-input:focus {
    border-color: var(--accent);
    background: rgba(255, 255, 255, 0.15);
}

.page-separator {
    opacity: 0.5;
}

.zoom-select {
    font-size: 12px;
    min-width: 60px;
    text-align: center;
    background: rgba(255, 255, 255, 0.1);
    color: inherit;
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 4px;
    padding: 2px 4px;
    cursor: pointer;
    outline: none;
}

.zoom-select:hover {
    background: rgba(255, 255, 255, 0.2);
}

.zoom-select option {
    background: var(--toolbar-bg);
    color: var(--text-color);
}

/* --- Sidebar --- */
.sidebar {
    position: fixed;
    top: 48px;
    left: 0;
    bottom: 44px;
    width: var(--sidebar-width);
    background: var(--sidebar-bg);
    z-index: 90;
    display: flex;
    flex-direction: column;
    box-shadow: 2px 0 12px rgba(0, 0, 0, 0.1);
    transition: transform var(--transition-speed) ease;
}

.sidebar.hidden {
    display: flex !important;
    transform: translateX(-100%);
    pointer-events: none;
}

.sidebar:not(.hidden) {
    transform: translateX(0);
}

.sidebar-tabs {
    display: flex;
    border-bottom: 1px solid #ddd;
    flex-shrink: 0;
}

.sidebar-tab {
    flex: 1;
    padding: 10px 12px;
    border: none;
    background: transparent;
    cursor: pointer;
    font-size: 12px;
    font-weight: 600;
    color: #666;
    transition: color 0.2s, border-color 0.2s;
    border-bottom: 2px solid transparent;
}

.sidebar-tab.active {
    color: var(--accent);
    border-bottom-color: var(--accent);
}

.sidebar-tab:hover {
    color: #333;
}

.sidebar-content {
    flex: 1;
    overflow-y: auto;
    padding: 8px;
}

/* Thumbnails */
.thumbnail-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 8px;
}

.thumbnail-item {
    position: relative;
    cursor: pointer;
    border: 2px solid transparent;
    border-radius: 6px;
    overflow: hidden;
    transition: border-color 0.2s, transform 0.2s;
    background: #fff;
    box-shadow: 0 1px 4px rgba(0, 0, 0, 0.08);
}

.thumbnail-item:hover {
    border-color: var(--accent);
    transform: translateY(-1px);
}

.thumbnail-item.active {
    border-color: var(--accent);
    box-shadow: 0 0 0 2px rgba(233, 69, 96, 0.2);
}

.thumbnail-item canvas {
    width: 100%;
    height: auto;
    display: block;
}

.thumbnail-label {
    font-size: 11px;
    text-align: center;
    padding: 4px;
    color: #666;
    background: #f9f9f9;
}

/* Bookmarks */
.bookmark-list {
    padding: 8px;
}

.no-bookmarks {
    font-size: 13px;
    color: #999;
    text-align: center;
    padding: 24px 12px;
}

.bookmark-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 8px 12px;
    border-radius: 6px;
    cursor: pointer;
    transition: background 0.2s;
    font-size: 13px;
}

.bookmark-item:hover {
    background: rgba(0, 0, 0, 0.05);
}

.bookmark-remove {
    border: none;
    background: transparent;
    color: #999;
    cursor: pointer;
    font-size: 16px;
    padding: 2px 6px;
    border-radius: 4px;
}

.bookmark-remove:hover {
    background: rgba(233, 69, 96, 0.1);
    color: var(--accent);
}

/* --- Main Viewer --- */
.viewer {
    flex: 1;
    position: relative;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--viewer-bg);
    transition: margin-left var(--transition-speed) ease;
}

.viewer.sidebar-open {
    margin-left: var(--sidebar-width);
}

/* ========== Book / Flipbook Container ========== */
.flipbook-container {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
    overflow: hidden;
    cursor: default;
}

.flipbook-container.is-zoomed {
    cursor: grab;
}

.flipbook-container.is-zoomed:active {
    cursor: grabbing;
}

.flipbook-book {
    position: relative;
    transition: none;
}

.book {
    position: relative;
    display: flex;
    box-shadow: 0 8px 40px rgba(0, 0, 0, 0.35), 0 2px 10px rgba(0, 0, 0, 0.18);
    border-radius: 4px;
    transition: none;
}

/* ---- Book pages (left / right halves) ---- */
.book-page {
    position: relative;
    width: 50%;
    height: 100%;
    overflow: hidden;
    background: var(--page-bg);
    transition: width 0.3s ease, opacity 0.3s ease;
}

.book-left {
    border-radius: 4px 0 0 4px;
}

.book-right {
    border-radius: 0 4px 4px 0;
}

.book-page.empty {
    background: #fff;
}

/* Single-page spread (cover / back cover) */
.book.single-page .book-page {
    width: 100%;
}

.book.single-page .book-page.empty {
    width: 0;
    opacity: 0;
    overflow: hidden;
}

.book.single-page::after {
    display: none;
}

.book.single-page {
    border-radius: 4px;
}

.book-page .page-content {
    width: 100%;
    height: 100%;
}

.book-page .page-content canvas {
    display: block;
    width: 100%;
    height: 100%;
}

/* Shadow overlay on pages during flip */
.book-page .page-shadow-overlay {
    position: absolute;
    inset: 0;
    pointer-events: none;
    z-index: 4;
    opacity: 0;
    transition: opacity 0.35s ease;
}

.book-left .page-shadow-overlay {
    background: linear-gradient(to left, rgba(0, 0, 0, 0.4) 0%, transparent 70%);
}

.book-right .page-shadow-overlay {
    background: linear-gradient(to right, rgba(0, 0, 0, 0.4) 0%, transparent 70%);
}

/* Subtle spine shadow between the two pages */
.book::after {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 12px;
    height: 100%;
    z-index: 6;
    pointer-events: none;
    background: linear-gradient(to right,
        rgba(0,0,0,0.12) 0%,
        rgba(0,0,0,0.03) 30%,
        rgba(255,255,255,0.08) 50%,
        rgba(0,0,0,0.03) 70%,
        rgba(0,0,0,0.12) 100%
    );
}

/* ========== 3D Flip Element ========== */
.flip-element {
    position: absolute;
    top: 0;
    width: 50%;
    height: 100%;
    transform-style: preserve-3d;
    z-index: 10;
    will-change: transform;
    /* Animation is set via JS for button flips; drag flips set their own */
}

/* Forward flip: covers right half, hinge at spine (left edge) */
.flip-element.flip-forward {
    left: 50%;
    transform-origin: left center;
}

/* Backward flip: covers left half, hinge at spine (right edge) */
.flip-element.flip-backward {
    left: 0;
    transform-origin: right center;
}

/* Front and back faces */
.flip-front, .flip-back {
    position: absolute;
    inset: 0;
    backface-visibility: hidden;
    overflow: hidden;
    background: var(--page-bg);
}

.flip-front {
    z-index: 2;
}

.flip-back {
    transform: rotateY(180deg);
    z-index: 1;
}

.flip-front .page-content,
.flip-back .page-content {
    width: 100%;
    height: 100%;
}

.flip-front .page-content canvas,
.flip-back .page-content canvas {
    display: block;
    width: 100%;
    height: 100%;
}

/* Gradient on the flip faces — driven dynamically by JS (turn.js style) */
.flip-gradient {
    position: absolute;
    inset: 0;
    pointer-events: none;
    z-index: 3;
}

/* Static defaults removed — JS drives gradients via rAF for synchronized shadow updates */

/* Navigation Arrows */
.nav-arrow {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 48px;
    height: 72px;
    border: none;
    background: rgba(0, 0, 0, 0.25);
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.2s, opacity 0.2s;
    opacity: 0;
    z-index: 20;
    border-radius: 8px;
}

.viewer:hover .nav-arrow {
    opacity: 1;
}

.nav-arrow:hover {
    background: rgba(0, 0, 0, 0.5);
}

.nav-arrow-left {
    left: 12px;
}

.nav-arrow-right {
    right: 12px;
}

/* --- Scrubber --- */
.scrubber {
    position: relative;
    height: 44px;
    padding: 0 20px;
    display: flex;
    align-items: center;
    background: var(--toolbar-bg);
    flex-shrink: 0;
    z-index: 100;
}

.scrubber-range {
    width: 100%;
    height: 4px;
    -webkit-appearance: none;
    appearance: none;
    background: rgba(255, 255, 255, 0.15);
    border-radius: 2px;
    outline: none;
    cursor: pointer;
}

.scrubber-range::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 16px;
    height: 16px;
    background: var(--accent);
    border-radius: 50%;
    cursor: pointer;
    border: 2px solid #fff;
    box-shadow: 0 1px 4px rgba(0, 0, 0, 0.3);
    transition: transform 0.15s;
}

.scrubber-range::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}

.scrubber-range::-moz-range-thumb {
    width: 16px;
    height: 16px;
    background: var(--accent);
    border-radius: 50%;
    cursor: pointer;
    border: 2px solid #fff;
    box-shadow: 0 1px 4px rgba(0, 0, 0, 0.3);
}

.scrubber-preview {
    position: absolute;
    bottom: 52px;
    background: #fff;
    border-radius: 6px;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.25);
    padding: 6px;
    pointer-events: none;
    z-index: 110;
    transform: translateX(-50%);
    transition: opacity 0.15s ease, transform 0.15s ease;
}

.scrubber-preview.hidden {
    opacity: 0;
    transform: translateX(-50%) translateY(6px);
    pointer-events: none;
}

/* Small arrow pointing down toward the scrubber */
.scrubber-preview::after {
    content: '';
    position: absolute;
    bottom: -6px;
    left: 50%;
    transform: translateX(-50%);
    border-left: 7px solid transparent;
    border-right: 7px solid transparent;
    border-top: 7px solid #fff;
}

.scrubber-preview canvas {
    border-radius: 4px;
    display: block;
    max-width: 120px;
}

.scrubber-preview .preview-label {
    text-align: center;
    font-size: 11px;
    font-weight: 500;
    color: #555;
    padding: 3px 0 1px;
    white-space: nowrap;
}

/* --- Modals --- */
.modal-overlay {
    position: fixed;
    inset: 0;
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--modal-overlay);
    animation: fadeIn 0.2s ease;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.modal {
    background: #fff;
    border-radius: 12px;
    max-width: 480px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    animation: slideUp 0.3s ease;
}

@keyframes slideUp {
    from { transform: translateY(20px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 16px 20px;
    border-bottom: 1px solid #eee;
}

.modal-header h3 {
    font-size: 16px;
    font-weight: 600;
}

.modal-close {
    border: none;
    background: transparent;
    font-size: 24px;
    cursor: pointer;
    color: #999;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 6px;
    transition: background 0.2s;
}

.modal-close:hover {
    background: #f0f0f0;
    color: #333;
}

.modal-body {
    padding: 20px;
}

/* Share Buttons */
.share-buttons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
    margin-bottom: 20px;
}

.share-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 14px;
    border: 1px solid #e0e0e0;
    border-radius: 8px;
    background: #fff;
    cursor: pointer;
    font-size: 13px;
    font-family: inherit;
    transition: background 0.2s, border-color 0.2s, transform 0.1s;
}

.share-btn:hover {
    background: #f7f7f7;
    border-color: #ccc;
    transform: translateY(-1px);
}

.share-btn:active {
    transform: translateY(0);
}

.share-facebook { color: #1877f2; }
.share-twitter { color: #000; }
.share-linkedin { color: #0a66c2; }
.share-email { color: #666; }

.share-link-container,
.embed-code-container {
    margin-top: 16px;
}

.share-link-container label,
.embed-code-container label {
    display: block;
    font-size: 12px;
    font-weight: 600;
    color: #666;
    margin-bottom: 6px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.share-link-row {
    display: flex;
    gap: 8px;
}

.share-link-input {
    flex: 1;
    padding: 8px 12px;
    border: 1px solid #ddd;
    border-radius: 6px;
    font-size: 13px;
    font-family: monospace;
    background: #f9f9f9;
    color: #333;
    outline: none;
}

.share-link-input:focus {
    border-color: var(--accent);
}

.embed-code {
    flex: 1;
    width: 100%;
    padding: 8px 12px;
    border: 1px solid #ddd;
    border-radius: 6px;
    font-size: 12px;
    font-family: monospace;
    background: #f9f9f9;
    color: #333;
    resize: vertical;
    outline: none;
}

.embed-code:focus {
    border-color: var(--accent);
}

.btn-copy {
    padding: 8px 16px;
    border: none;
    background: var(--accent);
    color: #fff;
    border-radius: 6px;
    cursor: pointer;
    font-size: 13px;
    font-weight: 600;
    font-family: inherit;
    transition: background 0.2s;
    white-space: nowrap;
}

.btn-copy:hover {
    background: var(--accent-hover);
}

.btn-copy.copied {
    background: #27ae60;
}

/* --- Responsive Design --- */

/* Tablet */
@media (max-width: 1024px) {
    .toolbar-title {
        max-width: 120px;
    }
    
    .toolbar-divider {
        display: none;
    }
    
    .zoom-select {
        display: none;
    }
}

/* Mobile */
@media (max-width: 768px) {
    .app {
        padding-top: env(safe-area-inset-top);
        padding-bottom: env(safe-area-inset-bottom);
    }

    .toolbar {
        height: 44px;
        padding: 0 max(8px, env(safe-area-inset-left)) 0 max(8px, env(safe-area-inset-right));
        gap: 6px;
    }

    .toolbar-left,
    .toolbar-right {
        flex: 0 0 auto;
    }

    .toolbar-center {
        position: static;
        left: auto;
        transform: none;
        flex: 1 1 auto;
        justify-content: center;
        min-width: 0;
        gap: 2px;
        max-width: 96px;
    }

    .toolbar-center .page-indicator {
        gap: 2px;
        font-size: 12px;
    }

    .toolbar-center .page-input {
        width: 30px;
        min-width: 30px;
        height: 24px;
        font-size: 12px;
        padding: 0;
    }

    .toolbar-center .page-separator,
    .toolbar-center #page-total {
        font-size: 11px;
        line-height: 1;
    }
    
    .toolbar-title {
        display: none;
    }
    
    .toolbar-btn {
        width: 44px;
        height: 44px;
    }
    
    .toolbar-right #btn-print,
    .toolbar-right .zoom-select {
        display: none;
    }

    .toolbar-center #btn-prev,
    .toolbar-center #btn-next {
        display: none;
    }
    
    .sidebar {
        width: 100%;
        top: 44px;
        bottom: 40px;
    }
    
    .viewer.sidebar-open {
        margin-left: 0;
    }
    
    .scrubber {
        height: calc(40px + env(safe-area-inset-bottom));
        padding: 0 max(12px, env(safe-area-inset-left)) env(safe-area-inset-bottom) max(12px, env(safe-area-inset-right));
    }
    
    .nav-arrow {
        width: 42px;
        height: 64px;
        opacity: 0.9;
    }
    
    .nav-arrow-left { left: 4px; }
    .nav-arrow-right { right: 4px; }
    
    .page-input {
        width: 36px;
        height: 26px;
    }
    
    .share-buttons {
        grid-template-columns: 1fr;
    }
    
    .modal {
        width: 95%;
        max-width: none;
        margin: 12px;
    }
}

.mobile-hint {
    position: fixed;
    left: 50%;
    bottom: calc(52px + env(safe-area-inset-bottom));
    transform: translateX(-50%);
    padding: 8px 12px;
    border-radius: 999px;
    font-size: 12px;
    font-weight: 600;
    color: #fff;
    background: rgba(26, 26, 46, 0.88);
    z-index: 1200;
    pointer-events: none;
    transition: opacity 0.2s ease;
    opacity: 1;
}

.mobile-hint.hidden {
    opacity: 0;
}

/* Small phones */
@media (max-width: 480px) {
    .toolbar-center {
        gap: 0;
    }

    .toolbar {
        padding-left: max(6px, env(safe-area-inset-left));
        padding-right: max(6px, env(safe-area-inset-right));
    }

    .page-input {
        width: 32px;
    }
    
    .toolbar-right #btn-share {
        display: none;
    }
}

/* Print styles */
@media print {
    .toolbar, .sidebar, .scrubber, .nav-arrow, .modal-overlay {
        display: none !important;
    }
    
    .app {
        display: block;
        height: auto;
    }
    
    .viewer {
        margin: 0;
        overflow: visible;
    }
    
    .page {
        page-break-after: always;
        box-shadow: none;
    }
}

/* --- Utility / Animation --- */
.fade-in {
    animation: fadeIn 0.3s ease;
}

/* Touch feedback */
@media (hover: none) {
    .toolbar-btn:active {
        background: var(--toolbar-active);
    }
    
    .nav-arrow {
        opacity: 0.6;
    }
}

/* Scrollbar styling */
.sidebar-content::-webkit-scrollbar {
    width: 6px;
}

.sidebar-content::-webkit-scrollbar-track {
    background: transparent;
}

.sidebar-content::-webkit-scrollbar-thumb {
    background: #ccc;
    border-radius: 3px;
}

.sidebar-content::-webkit-scrollbar-thumb:hover {
    background: #aaa;
}

/* Focus visible for keyboard navigation */
.toolbar-btn:focus-visible,
.nav-arrow:focus-visible,
.sidebar-tab:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

/* High contrast mode */
@media (prefers-contrast: high) {
    .toolbar { border-bottom: 2px solid #fff; }
    .scrubber { border-top: 2px solid #fff; }
    .page { border: 1px solid #000; }
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        transition-duration: 0.01ms !important;
    }
}