:root {
    --sidebar-width: 280px;
    --toolbar-height: 56px;
    --header-height: 56px;
    --statusbar-height: 24px;
    --primary-color: #4361ee;
    --secondary-color: #3f37c9;
    --success-color: #4cc9f0;
    --danger-color: #f72585;
    --warning-color: #f8961e;
    --light-bg: #121212; /* Changed to dark */
    --dark-bg: #121212;
    --card-bg: #1e1e1e; /* Changed to dark */
    --dark-card-bg: #1e1e1e;
    --border-color: #333; /* Changed to dark */
    --dark-border-color: #333;
    --text-color: #e0e0e0; /* Changed to light */
    --dark-text-color: #e0e0e0;
    --muted-color: #aaa; /* Changed to light */
    --dark-muted-color: #aaa;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif, 'Arial', 'Helvetica', sans-serif;
    background-color: var(--light-bg); /* Now dark */
    color: var(--text-color); /* Now light */
    overflow: hidden;
    transition: background-color 0.3s, color 0.3s;
    /* Mobile optimization: Reduce animations and transitions for better performance */
    -webkit-tap-highlight-color: transparent;
    -webkit-touch-callout: none;
    user-select: none;
    /* Touch optimization for mobile devices */
    touch-action: manipulation;
    -webkit-touch-action: manipulation;
    /* Touch optimization for mobile devices */
    touch-action: manipulation;
}

/* Arabic language support */
body[lang="ar"] {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif, 'Arial', 'Helvetica', sans-serif;
    direction: rtl;
}

/* Dark mode is now the default and only mode */
body {
    background-color: var(--dark-bg);
    color: var(--dark-text-color);
}

.bg-light {
    background-color: var(--dark-card-bg) !important;
}

.border {
    border-color: var(--dark-border-color) !important;
}

.border-bottom {
    border-bottom-color: var(--dark-border-color) !important;
}

.border-top {
    border-top-color: var(--dark-border-color) !important;
}

.border-end {
    border-right-color: var(--dark-border-color) !important;
}

.text-muted {
    color: var(--dark-muted-color) !important;
}

.btn-outline-light {
    color: var(--dark-text-color);
    border-color: #444;
}

.btn-outline-light:hover {
    background-color: #333;
}

.sidebar {
    width: var(--sidebar-width);
    background-color: var(--light-bg);
    transition: background-color 0.3s;
    /* Mobile optimization: Hardware acceleration */
    transform: translateZ(0);
}

.sidebar {
    background-color: var(--dark-bg);
}

.page-thumbnails {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
    gap: 10px;
}

.thumbnail-card {
    border: 2px solid var(--border-color);
    border-radius: 8px;
    overflow: hidden;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    background: var(--card-bg);
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    /* Mobile optimization: Larger touch targets */
    min-height: 44px;
    min-width: 44px;
    /* Touch optimization for mobile devices */
    touch-action: manipulation;
    -webkit-touch-action: manipulation;
}

.thumbnail-card {
    border-color: var(--dark-border-color);
    background: var(--dark-card-bg);
    box-shadow: 0 1px 3px rgba(0,0,0,0.3);
}

.thumbnail-card:hover {
    border-color: var(--primary-color);
    transform: translateY(-3px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.15);
}

.thumbnail-card:hover {
    box-shadow: 0 4px 8px rgba(0,0,0,0.4);
}

.thumbnail-card.selected {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(67, 97, 238, 0.25);
}

.thumbnail-card.drag-over {
    border-color: #198754;
    box-shadow: 0 0 0 2px rgba(25, 135, 84, 0.25);
}

.thumbnail-card.dragging {
    opacity: 0.5;
    transform: scale(0.95);
}

.thumbnail-img {
    width: 100%;
    height: 120px;
    object-fit: contain;
    background: var(--card-bg);
    transition: background-color 0.3s;
    /* Mobile optimization: Reduce image quality for better performance */
    image-rendering: -webkit-optimize-contrast;
}

.thumbnail-img {
    background: #333;
}

.thumbnail-info {
    padding: 4px;
    text-align: center;
    font-size: 0.75rem;
    background: rgba(0, 0, 0, 0.05);
    transition: background-color 0.3s;
}

.thumbnail-info {
    background: rgba(255, 255, 255, 0.05);
}

.page-preview {
    max-width: 90%;
    max-height: 70vh;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    transition: box-shadow 0.3s;
    /* Mobile optimization: Hardware acceleration */
    transform: translateZ(0);
}

.page-preview {
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

.drop-area {
    background: var(--card-bg);
    transition: background-color 0.3s, border-color 0.3s;
}

.drop-area {
    background: var(--dark-card-bg);
}

.drop-area.active {
    background: rgba(67, 97, 238, 0.05);
    border-color: var(--primary-color) !important;
}

.border-dashed {
    border: 2px dashed var(--border-color) !important;
}

.border-dashed {
    border: 2px dashed var(--dark-border-color) !important;
}

.status-info {
    background-color: #d1ecf1;
    color: #0c5460;
    transition: background-color 0.3s, color 0.3s;
}

.status-info {
    background-color: #1a3a5f;
    color: #4d9eff;
}

.status-error {
    background-color: #5f1a1a;
    color: #ff6b6b;
}

/* Footer styling for light and dark modes */
.footer-credit {
    transition: background-color 0.3s, color 0.3s;
    border: 1px solid var(--border-color);
}

.footer-credit.bg-dark {
    background-color: #343a40 !important; /* Dark gray background */
    color: #000000 !important; /* Black text in light mode */
}

.footer-credit.bg-light {
    background-color: #f8f9fa !important; /* Light background */
    color: #000000 !important; /* Black text in light mode */
}

.footer-credit .text-light {
    color: #000000 !important; /* Black text in light mode */
}

.footer-credit .text-dark {
    color: #000000 !important; /* Black text in light mode */
}

.footer-credit {
    border-color: var(--dark-border-color);
}

.footer-credit.bg-dark {
    background-color: #343a40 !important; /* Dark gray background */
    color: #ffffff !important; /* White text */
}

.footer-credit.bg-light {
    background-color: #1e1e1e !important; /* Darker background for light variant */
    color: #ffffff !important; /* White text */
}

.footer-credit .text-light {
    color: #ffffff !important; /* White text */
}

.footer-credit .text-dark {
    color: #ffffff !important; /* White text */
}

.checkbox-container {
    position: absolute;
    top: 5px;
    left: 5px;
    z-index: 10;
    /* Mobile optimization: Larger touch target */
    padding: 5px;
    margin: -5px;
    /* Touch optimization for mobile devices */
    touch-action: manipulation;
    -webkit-touch-action: manipulation;
}

.checkbox-container input {
    margin: 0;
    width: 16px;
    height: 16px;
}

.insert-position-btn {
    text-align: start;
    /* Mobile optimization: Larger touch targets */
    min-height: 44px;
}

/* Scrollbar styling */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: #f1f1f1;
}

::-webkit-scrollbar-track {
    background: #2d2d2d;
}

::-webkit-scrollbar-thumb {
    background: #c1c1c1;
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: #555;
}

::-webkit-scrollbar-thumb:hover {
    background: #a1a1a1;
}

::-webkit-scrollbar-thumb:hover {
    background: #777;
}

/* Progress bar animation */
@keyframes progress-bar-stripes {
    0% {
        background-position-x: 1rem;
    }
}

.progress-bar {
    background-image: linear-gradient(45deg, rgba(255, 255, 255, 0.15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, 0.15) 50%, rgba(255, 255, 255, 0.15) 75%, transparent 75%, transparent);
    background-size: 1rem 1rem;
    animation: progress-bar-stripes 1s linear infinite;
    /* Mobile optimization: Smoother animation */
    transition: width 0.3s ease;
}

/* Button hover effects */
.btn {
    transition: all 0.2s ease-in-out;
    /* Mobile optimization: Reduce transition duration for better responsiveness */
    transition-duration: 0.1s;
    /* Larger touch targets for mobile */
    min-height: 44px;
    min-width: 44px;
    /* Touch optimization for mobile devices */
    touch-action: manipulation;
    -webkit-touch-action: manipulation;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

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

/* Modal improvements */
.modal-content {
    border: none;
    box-shadow: 0 0.5rem 1rem rgba(0, 0, 0, 0.15);
    /* Mobile optimization: Hardware acceleration */
    transform: translateZ(0);
}

.modal-content {
    background-color: var(--dark-card-bg);
    color: var(--dark-text-color);
}

/* RTL (Right-to-Left) support for Arabic language */
[dir="rtl"] .me-2 {
    margin-right: 0 !important;
    margin-left: 0.5rem !important;
}

[dir="rtl"] .ms-2 {
    margin-left: 0 !important;
    margin-right: 0.5rem !important;
}

[dir="rtl"] .me-3 {
    margin-right: 0 !important;
    margin-left: 1rem !important;
}

[dir="rtl"] .ms-3 {
    margin-left: 0 !important;
    margin-right: 1rem !important;
}

[dir="rtl"] .float-end {
    float: left !important;
}

[dir="rtl"] .float-start {
    float: right !important;
}

[dir="rtl"] .text-end {
    text-align: left !important;
}

[dir="rtl"] .text-start {
    text-align: right !important;
}

/* Responsive design */
@media (max-width: 768px) {
    .sidebar {
        width: 100%;
        height: 200px;
    }
    
    .page-thumbnails {
        grid-template-columns: repeat(auto-fill, minmax(80px, 1fr));
    }
    
    .thumbnail-img {
        height: 80px;
    }
    
    .container-fluid {
        padding: 0.5rem !important;
    }
    
    .p-3 {
        padding: 0.5rem !important;
    }
    
    .p-2 {
        padding: 0.5rem !important;
    }
    
    .h4-md {
        font-size: 1.25rem;
    }
    
    .flex-fill.flex-md-unfill {
        flex: 0 0 auto;
    }
    
    .w-100.w-md-auto {
        width: 100%;
    }
    
    /* Mobile optimization: Reduce animations */
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

@media (min-width: 768px) {
    .h4-md {
        font-size: 1.5rem;
    }
    
    .flex-fill.flex-md-unfill {
        flex: 0 0 auto;
    }
    
    .w-100.w-md-auto {
        width: auto;
    }
    
    .sidebar {
        width: var(--sidebar-width);
        height: auto !important;
    }
    
    #thumbnailsSidebar .collapse:not(.show) {
        display: block;
    }
}

/* Mobile-specific optimizations */
@media screen and (max-width: 480px) {
    .sidebar, .modal-content, .container, .file-info, .page-preview {
        transform: none !important;
        will-change: auto !important;
    }
}

/* Show Android-specific message only on Android devices */
.android-only {
    display: none;
}

/* JavaScript will add this class if running on Android */
.android .android-only {
    display: block;
}

/* Preview container - responsive design */
#previewContainer {
    min-height: 60vh;
    padding: 15px;
}

/* Preview canvas styling - responsive sizing */
.preview-canvas {
    max-width: 100%;
    max-height: 70vh;
    width: 100%;
    height: auto;
    object-fit: contain;
    background-color: white;
    border: 1px solid #ddd;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.preview-canvas {
    background-color: #333;
    border-color: #555;
}

/* Preview navigation buttons */
.preview-nav-btn {
    top: 50%;
    transform: translateY(-50%);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    z-index: 10;
    opacity: 0.7;
    transition: all 0.2s ease;
    border: none;
    background-color: rgba(255, 255, 255, 0.8);
    color: #333;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
}

.preview-nav-btn:hover {
    opacity: 1;
    transform: translateY(-50%) scale(1.1);
    background-color: rgba(255, 255, 255, 1);
}

.preview-nav-btn:disabled {
    opacity: 0.3;
    cursor: not-allowed;
    transform: translateY(-50%);
}

body.dark-mode .preview-nav-btn {
    background-color: rgba(30, 30, 30, 0.8);
    color: white;
}

body.dark-mode .preview-nav-btn:hover:not(:disabled) {
    background-color: rgba(67, 97, 238, 0.8);
}

/* Responsive adjustments for navigation buttons */
@media (max-width: 768px) {
    .preview-nav-btn {
        width: 36px;
        height: 36px;
        font-size: 1rem;
    }
}

@media (max-width: 480px) {
    .preview-nav-btn {
        width: 32px;
        height: 32px;
        font-size: 0.9rem;
    }
    
    /* On very small screens, move buttons inside the canvas area */
    .preview-nav-btn {
        top: auto;
        bottom: 70px;
        transform: none;
    }
    
    #prevPageBtn {
        left: 10px;
    }
    
    #nextPageBtn {
        right: 10px;
    }
}

/* Large screens */
@media (min-width: 1200px) {
    .preview-nav-btn {
        width: 45px;
        height: 45px;
        font-size: 1.3rem;
    }
}

/* Language selector */
.language-selector {
    font-family: inherit;
    font-size: 0.875rem;
}

[dir="rtl"] .language-selector {
    text-align: right;
}

/* Preview controls */
#previewControls {
    background: rgba(255, 255, 255, 0.9);
    border-radius: 8px;
    padding: 8px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    backdrop-filter: blur(5px);
    border: 1px solid rgba(0, 0, 0, 0.1);
}

#previewControls {
    background: rgba(30, 30, 30, 0.9);
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

#previewControls .btn {
    min-width: 36px;
    min-height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1rem;
    padding: 6px;
    margin: 0 2px;
    border-width: 2px;
    transition: all 0.2s ease;
    /* Touch optimization for mobile devices */
    touch-action: manipulation;
    -webkit-touch-action: manipulation;
}

#previewControls .btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

#previewControls .btn:hover {
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.4);
}

#previewControls .btn:active {
    transform: translateY(0);
}

#previewControls .btn-outline-primary {
    background-color: rgba(67, 97, 238, 0.1);
    border-color: var(--primary-color);
    color: var(--primary-color);
}

#previewControls .btn-outline-primary:hover {
    background-color: var(--primary-color);
    color: white;
}

#previewControls .btn-outline-primary {
    background-color: rgba(67, 97, 238, 0.2);
}

#previewControls .btn-outline-danger {
    background-color: rgba(247, 37, 133, 0.1);
    border-color: var(--danger-color);
    color: var(--danger-color);
}

#previewControls .btn-outline-danger:hover {
    background-color: var(--danger-color);
    color: white;
}

#previewControls .btn-outline-danger {
    background-color: rgba(247, 37, 133, 0.2);
}

/* Cache info display */
.cache-info {
    position: absolute;
    top: 10px;
    left: 10px;
    background-color: rgba(13, 110, 253, 0.9);
    color: white;
    padding: 5px 10px;
    border-radius: 4px;
    font-size: 0.8rem;
    z-index: 1000;
    backdrop-filter: blur(2px);
}

.cache-info {
    background-color: rgba(25, 118, 210, 0.9);
}

/* Responsive adjustments */
@media (max-width: 768px) {
    #previewContainer {
        min-height: 50vh;
        padding: 10px;
    }
    
    .preview-nav-btn {
        width: 36px;
        height: 36px;
        font-size: 1rem;
    }
    
    #previewControls .btn {
        min-width: 32px;
        min-height: 32px;
        font-size: 0.9rem;
        padding: 5px;
    }
    
    #previewControls {
        padding: 6px;
    }
}

@media (max-width: 480px) {
    #previewContainer {
        min-height: 45vh;
        padding: 8px;
    }
    
    .preview-nav-btn {
        width: 32px;
        height: 32px;
        font-size: 0.9rem;
    }
    
    #previewControls .btn {
        min-width: 28px;
        min-height: 28px;
        font-size: 0.8rem;
        padding: 4px;
    }
    
    #previewControls {
        padding: 4px;
    }
}

@media (min-width: 1200px) {
    .preview-canvas {
        max-width: 800px;
        max-height: 600px;
    }
}