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

:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-color: #64748b;
    --success-color: #10b981;
    --error-color: #ef4444;
    --bg-color: #f1f5f9;
    --card-bg: #ffffff;
    --border-color: #e2e8f0;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --header-bg: #1e40af;
    --header-text: #ffffff;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.app-container {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* Header */
.app-header {
    background: var(--header-bg);
    color: var(--header-text);
    padding: 1rem 2rem;
    box-shadow: var(--shadow-lg);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--header-text);
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.selection-count {
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.9);
}

.btn-select-all {
    background: rgba(255, 255, 255, 0.2);
    color: var(--header-text);
    border: 1px solid rgba(255, 255, 255, 0.3);
    padding: 0.5rem 1rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.2s;
}

.btn-select-all:hover {
    background: rgba(255, 255, 255, 0.3);
}

/* Main Layout */
.main-layout {
    display: flex;
    flex: 1;
    max-width: 1400px;
    margin: 0 auto;
    width: 100%;
    padding: 2rem;
    gap: 2rem;
}

/* Card Selection Area */
.card-selection-area {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.upload-section {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.upload-card, .config-card {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 2rem;
    box-shadow: var(--shadow);
}

.upload-card h2, .config-card h3 {
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.config-description {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.7;
}

.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    padding: 3rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    background: var(--bg-color);
}

.upload-area:hover {
    border-color: var(--primary-color);
    background: #f8fafc;
}

.upload-area.dragover {
    border-color: var(--primary-color);
    background: #eff6ff;
}

.upload-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
}

.upload-content svg {
    color: var(--primary-color);
}

.upload-content p {
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--text-primary);
}

.file-hint {
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-weight: normal;
}

.file-info {
    margin-top: 1rem;
    padding: 1rem;
    background: var(--bg-color);
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
}

/* Face Toggle */
.face-toggle-bar {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    background: var(--card-bg);
    padding: 0.5rem;
    border-radius: 8px;
    box-shadow: var(--shadow);
}

.face-toggle {
    flex: 1;
    padding: 0.75rem 1.5rem;
    border: 2px solid var(--border-color);
    background: transparent;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    color: var(--text-secondary);
    transition: all 0.2s;
}

.face-toggle:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.face-toggle.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* Cards Container */
.cards-section {
    display: flex;
    flex-direction: column;
}

.cards-container {
    display: flex;
    flex-wrap: wrap;
    gap: 1.5rem;
}

.card-slot {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 1rem;
    box-shadow: var(--shadow);
    width: 280px;
    position: relative;
    transition: transform 0.2s, box-shadow 0.2s;
}

.card-slot:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.card-slot-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.75rem;
}

.card-slot-label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.9rem;
}

.card-slot-checkbox {
    margin-right: 0.5rem;
}

.card-slot-delete {
    background: var(--error-color);
    color: white;
    border: none;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1rem;
    font-weight: bold;
    transition: all 0.2s;
}

.card-slot-delete:hover {
    background: #dc2626;
    transform: scale(1.1);
}

.card-image-container {
    position: relative;
    width: 100%;
    min-height: 200px;
    max-height: 400px;
    background: var(--bg-color);
    border-radius: 8px;
    overflow: hidden;
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    justify-content: center;
}

.card-image {
    max-width: 100%;
    max-height: 100%;
    width: auto;
    height: auto;
    object-fit: contain;
    background: white;
    display: block;
}

.card-info {
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-align: center;
    margin-bottom: 0.5rem;
}

.card-back-selector {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-top: 0.5rem;
    padding-top: 0.5rem;
    border-top: 1px solid var(--border-color);
}

.card-back-selector label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    flex: 1;
}

.card-back-selector select {
    flex: 1;
    padding: 0.4rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 0.85rem;
}

/* Sidebar */
.sidebar {
    width: 320px;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.summary-card, .settings-card, .cardback-card, .actions-card {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 1.5rem;
    box-shadow: var(--shadow);
}

.summary-card h3, .settings-card h3, .cardback-card h3 {
    margin-bottom: 1rem;
    color: var(--text-primary);
    font-size: 1.1rem;
}

.summary-content {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
}

.setting-group {
    margin-bottom: 1rem;
}

.setting-group:last-child {
    margin-bottom: 0;
}

.setting-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.9rem;
}

.select-input {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 0.9rem;
    font-family: inherit;
    background: white;
}

.select-input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.toggle {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
}

.toggle input[type="checkbox"] {
    width: 18px;
    height: 18px;
    cursor: pointer;
}

/* Cardback Section */
.cardback-upload-area {
    position: relative;
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    padding: 1rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s;
    min-height: 200px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.cardback-upload-area:hover {
    border-color: var(--primary-color);
    background: var(--bg-color);
}

.cardback-placeholder {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-secondary);
}

.cardback-placeholder svg {
    color: var(--primary-color);
}

.cardback-image {
    max-width: 100%;
    max-height: 300px;
    width: auto;
    height: auto;
    border-radius: 8px;
    object-fit: contain;
    display: block;
    margin: 0 auto;
}

.btn-remove-cardback {
    margin-top: 0.5rem;
    background: var(--error-color);
    color: white;
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.85rem;
    width: 100%;
}

.btn-remove-cardback:hover {
    background: #dc2626;
}

.cardback-hint {
    margin-top: 0.75rem;
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-align: center;
}

/* Buttons */
.btn-primary {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 0.875rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
    width: 100%;
}

.btn-primary:hover:not(:disabled) {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-lg);
}

.btn-primary:disabled {
    background: var(--secondary-color);
    cursor: not-allowed;
    opacity: 0.6;
}

.btn-secondary {
    background: white;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
    padding: 0.875rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
    width: 100%;
    margin-top: 0.75rem;
}

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

.btn-download {
    background: var(--success-color);
    color: white;
    border: none;
    padding: 0.875rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.btn-download:hover:not(:disabled) {
    background: #059669;
    transform: translateY(-1px);
    box-shadow: var(--shadow-lg);
}

.btn-download:disabled {
    background: var(--secondary-color);
    cursor: not-allowed;
    opacity: 0.6;
}

/* Input Groups */
.input-group {
    margin-bottom: 1rem;
}

.input-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

.text-input {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.2s;
    font-family: inherit;
}

.text-input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.hint {
    color: var(--text-secondary);
    font-size: 0.85rem;
    margin-top: 0.25rem;
    display: block;
}

.error-message {
    margin-top: 0.5rem;
    padding: 0.75rem;
    background: #fee2e2;
    color: var(--error-color);
    border-radius: 6px;
    border-left: 4px solid var(--error-color);
    font-size: 0.9rem;
}

/* Processing Overlay */
.processing-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.7);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.processing-content {
    background: white;
    padding: 3rem;
    border-radius: 12px;
    text-align: center;
    box-shadow: var(--shadow-lg);
}

.spinner {
    width: 48px;
    height: 48px;
    border: 4px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 1rem;
}

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

#processing-message {
    color: var(--text-primary);
    font-weight: 500;
}

/* Utility Classes */
.hidden {
    display: none !important;
}

/* Responsive */
@media (max-width: 1024px) {
    .main-layout {
        flex-direction: column;
    }

    .sidebar {
        width: 100%;
    }

    .cards-container {
        justify-content: center;
    }
}

@media (max-width: 640px) {
    .main-layout {
        padding: 1rem;
    }

    .header-content {
        flex-direction: column;
        gap: 1rem;
        align-items: flex-start;
    }

    .card-slot {
        width: 100%;
    }
}