/**
 * Premium Flip PDF Builder - 3D Flipbook Core CSS
 * Scoped under .pfpf-viewer namespace
 *
 * @package PremiumFlipPDF
 */

:root {
    --pfpf-font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --pfpf-bg: #12141a;
    --pfpf-stage-bg: transparent;
    --pfpf-toolbar-bg: rgba(22, 26, 35, 0.95);
    --pfpf-toolbar-border: rgba(255, 255, 255, 0.1);
    --pfpf-toolbar-text: #e2e8f0;
    --pfpf-toolbar-muted: #94a3b8;
    --pfpf-accent: #3b82f6;
    --pfpf-accent-hover: #60a5fa;
    --pfpf-book-shadow: 0 25px 60px -15px rgba(0, 0, 0, 0.6), 0 0 30px rgba(0, 0, 0, 0.35);
    --pfpf-spine-shadow: linear-gradient(to right, rgba(0, 0, 0, 0.25) 0%, rgba(0, 0, 0, 0.05) 50%, rgba(0, 0, 0, 0.25) 100%);
    --pfpf-page-radius: 4px;
    --pfpf-transition-speed: 0.3s;
}

/* ==========================================================================
   Root Viewer Container
   ========================================================================== */
.pfpf-viewer {
    position: relative;
    width: 100%;
    height: 750px;
    max-height: 90vh;
    min-height: 480px;
    background-color: var(--pfpf-bg);
    font-family: var(--pfpf-font-family);
    color: var(--pfpf-toolbar-text);
    overflow: hidden;
    user-select: none;
    -webkit-user-select: none;
    box-sizing: border-box;
    display: flex;
    flex-direction: column;
}

.pfpf-viewer *,
.pfpf-viewer *::before,
.pfpf-viewer *::after {
    box-sizing: border-box;
}

/* Fullscreen Mode */
.pfpf-viewer.pfpf-fullscreen {
    position: fixed !important;
    top: 0 !important;
    left: 0 !important;
    width: 100vw !important;
    height: 100vh !important;
    max-height: 100vh !important;
    z-index: 999999 !important;
    border-radius: 0 !important;
    margin: 0 !important;
}

/* ==========================================================================
   Optional Top Header / Branding
   ========================================================================== */
.pfpf-header {
    height: 48px;
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: rgba(15, 18, 26, 0.8);
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    z-index: 20;
    flex-shrink: 0;
}

.pfpf-header-branding {
    display: flex;
    align-items: center;
    gap: 12px;
}

.pfpf-header-logo img {
    max-height: 28px;
    width: auto;
    object-fit: contain;
}

.pfpf-header-title {
    font-size: 14px;
    font-weight: 600;
    color: #f1f5f9;
    letter-spacing: 0.2px;
}

/* ==========================================================================
   Main 3D Stage & Book Architecture
   ========================================================================== */
.pfpf-stage {
    position: relative;
    flex: 1;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    perspective: 2400px;
    -webkit-perspective: 2400px;
    overflow: hidden;
    background: var(--pfpf-stage-bg);
}

.pfpf-stage.pfpf-panning {
    cursor: grab;
}

.pfpf-stage.pfpf-panning:active {
    cursor: grabbing;
}

/* Book Container */
.pfpf-book {
    position: relative;
    transform-style: preserve-3d;
    -webkit-transform-style: preserve-3d;
    box-shadow: var(--pfpf-book-shadow);
    border-radius: var(--pfpf-page-radius);
    transition: transform 0.2s cubic-bezier(0.2, 0, 0, 1);
    transform-origin: center center;
}

/* Spread Container */
.pfpf-spread {
    position: relative;
    width: 100%;
    height: 100%;
    transform-style: preserve-3d;
    -webkit-transform-style: preserve-3d;
    border-radius: var(--pfpf-page-radius);
    background: transparent !important;
}

/* Pages (Left / Right) */
.pfpf-page {
    position: absolute;
    top: 0;
    height: 100%;
    overflow: hidden;
    background: #ffffff;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
}

.pfpf-page-left {
    left: 0;
    width: 50%;
    border-top-left-radius: var(--pfpf-page-radius);
    border-bottom-left-radius: var(--pfpf-page-radius);
    border-right: none !important;
}

.pfpf-page-right {
    left: 50%;
    right: auto;
    width: 50%;
    border-top-right-radius: var(--pfpf-page-radius);
    border-bottom-right-radius: var(--pfpf-page-radius);
    border-left: none !important;
}

.pfpf-page-content {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.pfpf-page-content canvas {
    display: block;
    width: 100%;
    height: 100%;
    object-fit: fill;
}

/* Page Overlay for realistic paper lighting */
.pfpf-page-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    background: linear-gradient(to right, rgba(0,0,0,0.02) 0%, rgba(255,255,255,0.03) 50%, rgba(0,0,0,0.02) 100%);
}

/* Center Spine */
.pfpf-spine {
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 6px;
    height: 100%;
    background: linear-gradient(to right, rgba(0, 0, 0, 0.12) 0%, rgba(0, 0, 0, 0.02) 50%, rgba(0, 0, 0, 0.12) 100%);
    pointer-events: none;
    z-index: 30;
    mix-blend-mode: multiply;
}

/* 3D Flipper Layer */
.pfpf-flipper {
    position: absolute;
    top: 0;
    height: 100%;
    transform-style: preserve-3d;
    -webkit-transform-style: preserve-3d;
    z-index: 25;
    pointer-events: none;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
}

.pfpf-flipper-face {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
    overflow: hidden;
    background: #ffffff;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.12);
}

.pfpf-flipper-front {
    z-index: 2;
    transform: rotateY(0deg);
}

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

.pfpf-flipper-face canvas {
    display: block;
    width: 100%;
    height: 100%;
}

.pfpf-flipper-shadow-front,
.pfpf-flipper-shadow-back {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.2s ease;
}

.pfpf-flipper-shadow-front {
    background: linear-gradient(to left, rgba(0,0,0,0.4) 0%, rgba(0,0,0,0.05) 60%, transparent 100%);
}

.pfpf-flipper-shadow-back {
    background: linear-gradient(to right, rgba(0,0,0,0.4) 0%, rgba(0,0,0,0.05) 60%, transparent 100%);
}

/* Engine Styles */
.pfpf-engine-physical .pfpf-page { transform-origin: left; }
.pfpf-engine-slide .pfpf-page { transition: transform 0.5s ease-in-out; }
.pfpf-engine-vertical .pfpf-page { transform-origin: top; }
.pfpf-engine-curl .pfpf-page { backface-visibility: visible; }
.pfpf-engine-stack .pfpf-page { position: absolute; z-index: 1; }
.pfpf-engine-fade .pfpf-page { transition: opacity 0.5s ease; }

/* ==========================================================================
   Side Navigation Arrows
   ========================================================================== */
.pfpf-nav {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 48px !important;
    height: 48px !important;
    min-width: 48px !important;
    min-height: 48px !important;
    border-radius: 50% !important;
    background: rgba(22, 26, 35, 0.8) !important;
    border: 1px solid rgba(255, 255, 255, 0.15) !important;
    color: #ffffff !important;
    display: inline-flex !important;
    align-items: center !important;
    justify-content: center !important;
    cursor: pointer !important;
    z-index: 30;
    padding: 0 !important;
    backdrop-filter: blur(6px);
    -webkit-backdrop-filter: blur(6px);
    transition: background 0.2s ease, transform 0.2s ease, box-shadow 0.2s ease;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.35);
}

.pfpf-nav:hover:not(:disabled) {
    background: var(--pfpf-accent) !important;
    transform: translateY(-50%) scale(1.08) !important;
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.5) !important;
}

.pfpf-nav:active:not(:disabled) {
    transform: translateY(-50%) scale(0.96) !important;
}

.pfpf-nav:disabled {
    opacity: 0.25 !important;
    cursor: not-allowed !important;
}

.pfpf-nav-prev {
    left: 20px;
}

.pfpf-nav-next {
    right: 20px;
}

.pfpf-viewer .pfpf-nav svg,
.pfpf-nav svg {
    width: 24px !important;
    height: 24px !important;
    min-width: 24px !important;
    min-height: 24px !important;
    max-width: 24px !important;
    max-height: 24px !important;
    display: inline-block !important;
    vertical-align: middle !important;
    fill: currentColor !important;
    stroke: none !important;
    flex-shrink: 0 !important;
    visibility: visible !important;
    opacity: 1 !important;
}

/* ==========================================================================
   Loading & Error Overlays
   ========================================================================== */
.pfpf-loading-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--pfpf-bg);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 100;
    transition: opacity 0.3s ease, visibility 0.3s ease;
}

.pfpf-loading-overlay.pfpf-hidden {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
}

.pfpf-spinner {
    width: 44px;
    height: 44px;
    border: 3px solid rgba(255, 255, 255, 0.1);
    border-top-color: var(--pfpf-accent);
    border-radius: 50%;
    animation: pfpf-spin 0.8s linear infinite;
}

.pfpf-loading-text {
    margin-top: 16px;
    font-size: 13px;
    font-weight: 500;
    color: var(--pfpf-toolbar-muted);
    letter-spacing: 0.5px;
}

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

.pfpf-error-box {
    text-align: center;
    padding: 30px;
    max-width: 400px;
}

.pfpf-error-icon {
    font-size: 36px;
    margin-bottom: 12px;
}

.pfpf-error-msg {
    font-size: 14px;
    color: #ef4444;
    margin-bottom: 16px;
    line-height: 1.5;
}

.pfpf-btn-retry {
    padding: 8px 18px;
    background: var(--pfpf-accent);
    color: #ffffff;
    border: none;
    border-radius: 6px;
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
}