:root {
    --primary-color: #f59e0b;
    --primary-hover: #d97706;
    --secondary-color: #fef3c7;
    --secondary-hover: #fde68a;
    --bg-color: #fffbeb;
    --text-color: #451a03;
    --card-bg: #ffffff;
    --border-color: #fcd34d;
    --danger-color: #ef4444;
    --success-color: #22c55e;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Noto Sans TC', sans-serif;
    background-color: var(--bg-color);
    background-image: 
        radial-gradient(at 0% 0%, rgba(253, 230, 138, 0.6) 0px, transparent 50%),
        radial-gradient(at 100% 100%, rgba(251, 146, 60, 0.3) 0px, transparent 50%);
    background-attachment: fixed;
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.app-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
    flex: 1;
    display: flex;
    flex-direction: column;
    width: 100%;
}

/* Header */
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 2rem;
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(10px);
    border-radius: 16px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -1px rgba(0, 0, 0, 0.03);
    border: 1px solid rgba(255,255,255,0.8);
    margin-bottom: 2rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.header-content {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.header-icon {
    font-size: 2rem;
    color: var(--primary-color);
}

.header h1 {
    font-size: 1.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, #f59e0b, #ea580c);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.action-buttons {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    font-weight: 500;
    font-size: 0.95rem;
    cursor: pointer;
    border: none;
    transition: all 0.2s ease;
    font-family: inherit;
}

.btn:active {
    transform: translateY(1px);
}

.btn-primary {
    background: linear-gradient(135deg, #f59e0b, #ea580c);
    color: white;
    box-shadow: 0 4px 12px rgba(245, 158, 11, 0.3);
}

.btn-primary:hover {
    box-shadow: 0 6px 16px rgba(234, 88, 12, 0.4);
    transform: translateY(-2px);
}

.btn-secondary {
    background-color: white;
    color: var(--primary-color);
    border: 1px solid var(--secondary-hover);
}

.btn-secondary:hover {
    background-color: var(--secondary-color);
}

.btn-icon {
    padding: 0.5rem;
    background: rgba(255,255,255,0.9);
    backdrop-filter: blur(4px);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-color);
    cursor: pointer;
    transition: all 0.2s;
    font-size: 1.2rem;
}

.btn-icon:hover {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* Main Content */
.main-content {
    flex: 1;
    position: relative;
    display: flex;
    flex-direction: column;
}

/* Upload Area */
.upload-area {
    display: flex;
    justify-content: center;
    align-items: center;
    flex: 1;
    min-height: 400px;
    transition: all 0.3s;
}

.upload-box {
    background: rgba(255, 255, 255, 0.6);
    backdrop-filter: blur(8px);
    border: 2px dashed var(--primary-hover);
    border-radius: 24px;
    padding: 4rem 2rem;
    text-align: center;
    max-width: 600px;
    width: 100%;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.05);
}

.upload-box.dragover {
    background: var(--secondary-color);
    border-color: var(--primary-color);
    transform: scale(1.02);
}

.upload-icon {
    font-size: 4rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.upload-box h2 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.upload-box p {
    color: #64748b;
    margin-bottom: 1.5rem;
}

.btn-upload {
    background: var(--primary-color);
    color: white;
    padding: 0.75rem 2rem;
    border-radius: 50px;
    font-size: 1.1rem;
}

.btn-upload:hover {
    background: var(--primary-hover);
}

/* Loading */
.loading-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255,255,255,0.8);
    backdrop-filter: blur(4px);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 10;
    border-radius: 16px;
}

.spinner {
    font-size: 3rem;
    color: var(--primary-color);
    animation: spin 1s linear infinite;
    margin-bottom: 1rem;
}

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

/* Pages Grid */
.pages-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 1.5rem;
    padding-bottom: 2rem;
}

.page-card {
    background: var(--card-bg);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    transition: all 0.3s ease;
    position: relative;
    border: 2px solid transparent;
    cursor: grab;
}

.page-card:active {
    cursor: grabbing;
}

.page-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

.page-card.selected {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 4px rgba(245, 158, 11, 0.3);
}

.page-preview {
    width: 100%;
    aspect-ratio: 1 / 1.414; /* A4 proportion approximately */
    background: #f1f5f9;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
    position: relative;
}

.page-preview canvas {
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
    transition: transform 0.3s ease;
}

.page-info {
    padding: 0.75rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: #fff;
    border-top: 1px solid var(--border-color);
}

.page-number {
    font-weight: 600;
    color: #475569;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

.page-actions {
    display: flex;
    gap: 0.5rem;
}

/* Checkbox overlay */
.checkbox-container {
    position: absolute;
    top: 0.5rem;
    left: 0.5rem;
    z-index: 2;
}

.custom-checkbox {
    display: none;
}

.checkbox-label {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    background: rgba(255,255,255,0.9);
    border: 2px solid #cbd5e1;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s;
    backdrop-filter: blur(4px);
}

.custom-checkbox:checked + .checkbox-label {
    background: var(--primary-color);
    border-color: var(--primary-color);
}

.custom-checkbox:checked + .checkbox-label::after {
    content: '\2714';
    color: white;
    font-size: 16px;
}

/* Sortable Ghost */
.sortable-ghost {
    opacity: 0.4;
    background: var(--secondary-color);
}

/* Footer */
.footer {
    margin-top: 2rem;
    padding-top: 1rem;
    border-top: 1px solid rgba(0,0,0,0.05);
    text-align: center;
    color: #64748b;
}

.footer-content {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 1rem;
    font-size: 0.9rem;
}

.version {
    background: var(--secondary-color);
    color: var(--primary-hover);
    padding: 0.2rem 0.6rem;
    border-radius: 12px;
    font-weight: 600;
    font-size: 0.8rem;
}

@media (max-width: 600px) {
    .header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .action-buttons {
        width: 100%;
        justify-content: space-between;
    }
    
    .btn {
        flex: 1;
        justify-content: center;
    }
}

/* Image Preview Modal */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background-color: rgba(0,0,0,0.8);
    backdrop-filter: blur(5px);
    justify-content: center;
    align-items: center;
}

.modal-content {
    margin: auto;
    display: block;
    max-width: 90%;
    max-height: 90%;
    box-shadow: 0 0 20px rgba(0,0,0,0.5);
    border-radius: 8px;
    animation: zoom 0.3s ease;
}

@keyframes zoom {
    from {transform:scale(0.8)} 
    to {transform:scale(1)}
}

.close-modal {
    position: absolute;
    top: 20px;
    right: 35px;
    color: #f1f1f1;
    font-size: 40px;
    font-weight: bold;
    cursor: pointer;
    transition: 0.3s;
}

.close-modal:hover,
.close-modal:focus {
    color: #f59e0b;
    text-decoration: none;
    cursor: pointer;
}