:root {
    --primary-color: #2196F3;
    --success-color: #4CAF50;
    --warning-color: #FFC107;
    --danger-color: #F44336;
    --purple-color: #9C27B0;
    --background-color: #f5f5f5;
    --surface-color: #ffffff;
    --text-primary: #212121;
    --text-secondary: #757575;
    --border-color: #e0e0e0;
    --shadow: 0 2px 8px rgba(0,0,0,0.1);
    --shadow-hover: 0 4px 16px rgba(0,0,0,0.15);
    --border-radius: 12px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--background-color);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    padding-bottom: 80px;
}

/* Informational banner */
.info-banner {
    background: #FFF3CD;
    color: #856404;
    border: 1px solid #FFEEBA;
    border-radius: var(--border-radius);
    padding: 0.75rem 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.info-inline {
    background: rgba(255, 243, 205, 0.6);
    color: #856404;
    border: 1px solid #FFEEBA;
    border-radius: 8px;
    padding: 0.5rem 0.75rem;
    font-size: 0.9rem;
    margin-top: 0.5rem;
}

/* Header */
.app-header {
    background: linear-gradient(135deg, var(--primary-color), var(--purple-color));
    color: white;
    padding: 1rem;
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
}

.header-content h1 {
    font-size: 1.5rem;
    font-weight: 600;
}

.language-toggle {
    position: relative;
}

.lang-btn {
    background: rgba(255,255,255,0.2);
    border: none;
    color: white;
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: var(--transition);
}

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

/* Main Content */
.app-main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem;
}

.app-section {
    display: none;
    animation: fadeIn 0.3s ease-in-out;
}

.app-section.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.section-header {
    text-align: center;
    margin-bottom: 2rem;
}

.section-header h2 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

.section-header p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* File Drop Zone */
.file-drop-zone {
    background: var(--surface-color);
    border: 2px dashed var(--border-color);
    border-radius: var(--border-radius);
    padding: 3rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    margin-bottom: 2rem;
}

.file-drop-zone:hover,
.file-drop-zone.drag-over {
    border-color: var(--primary-color);
    background: rgba(33, 150, 243, 0.05);
}

.drop-icon {
    font-size: 3rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.select-files-btn {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 1rem 2rem;
    border-radius: var(--border-radius);
    font-size: 1.1rem;
    cursor: pointer;
    margin-top: 1rem;
    transition: var(--transition);
}

.select-files-btn:hover {
    background: #1976D2;
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

/* Selected Files */
.selected-files {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow);
}

.files-list {
    margin: 1rem 0;
}

.file-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    margin-bottom: 0.5rem;
    background: #fafafa;
}

.file-info {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.file-icon {
    font-size: 1.5rem;
    color: var(--primary-color);
}

.file-details h4 {
    margin-bottom: 0.25rem;
}

.file-details p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.remove-file-btn {
    background: none;
    border: none;
    color: var(--danger-color);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 50%;
    transition: var(--transition);
}

.remove-file-btn:hover {
    background: rgba(244, 67, 54, 0.1);
}

/* Action Buttons */
.action-buttons {
    display: flex;
    gap: 1rem;
    margin-top: 1.5rem;
}

.btn {
    padding: 1rem 1.5rem;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: var(--transition);
    text-decoration: none;
    text-align: center;
    justify-content: center;
    flex: 1;
}

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

.btn-primary:hover {
    background: #1976D2;
}

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

.btn-secondary:hover {
    background: #616161;
}

.btn-danger {
    background: var(--danger-color);
    color: white;
}

.btn-danger:hover {
    background: #D32F2F;
}

.btn-success {
    background: var(--success-color);
    color: white;
}

.btn-success:hover {
    background: #388E3C;
}

/* Progress Container */
.progress-container {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow);
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--border-color);
    border-radius: 4px;
    overflow: hidden;
    margin: 1rem 0;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--success-color));
    width: 0%;
    transition: width 0.3s ease;
}

.progress-text {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-weight: 500;
}

/* Settings */
.settings-grid {
    display: grid;
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.setting-item {
    background: var(--surface-color);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.setting-item label {
    display: block;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.setting-select {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    background: white;
}

.checkbox-label {
    display: flex !important;
    align-items: center;
    cursor: pointer;
    margin-bottom: 0 !important;
}

.checkbox-label input[type="checkbox"] {
    display: none;
}

.checkmark {
    width: 20px;
    height: 20px;
    border: 2px solid var(--border-color);
    border-radius: 4px;
    margin-right: 0.75rem;
    position: relative;
    transition: var(--transition);
}

.checkbox-label input[type="checkbox"]:checked + .checkmark {
    background: var(--primary-color);
    border-color: var(--primary-color);
}

.checkbox-label input[type="checkbox"]:checked + .checkmark::after {
    content: "✓";
    position: absolute;
    color: white;
    font-size: 14px;
    top: -2px;
    left: 2px;
}

/* Danger Zone */
.danger-zone {
    background: rgba(244, 67, 54, 0.05);
    border: 1px solid rgba(244, 67, 54, 0.2);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-top: 2rem;
}

.danger-zone h3 {
    color: var(--danger-color);
    margin-bottom: 0.5rem;
}

.danger-zone p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

/* Logs */
.logs-controls {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.logs-container {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
    min-height: 300px;
}

.log-entry {
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
}

.log-entry:last-child {
    border-bottom: none;
}

.log-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
}

.log-timestamp {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.log-status {
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.8rem;
    font-weight: 500;
}

.log-status.success {
    background: rgba(76, 175, 80, 0.1);
    color: var(--success-color);
}

.log-status.error {
    background: rgba(244, 67, 54, 0.1);
    color: var(--danger-color);
}

.log-details {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.no-logs {
    text-align: center;
    color: var(--text-secondary);
    padding: 3rem;
    font-size: 1.1rem;
}

/* FAQ */
.faq-container {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    margin-bottom: 1rem;
    box-shadow: var(--shadow);
    overflow: hidden;
}

.faq-question {
    width: 100%;
    background: none;
    border: none;
    padding: 1.5rem;
    text-align: left;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 1.1rem;
    font-weight: 500;
    transition: var(--transition);
}

.faq-question:hover {
    background: rgba(33, 150, 243, 0.05);
}

.faq-icon {
    font-size: 1.2rem;
    color: var(--primary-color);
    transition: transform 0.3s ease;
}

.faq-question[aria-expanded="true"] .faq-icon {
    transform: rotate(45deg);
}

.faq-answer {
    padding: 0 1.5rem 1.5rem;
    color: var(--text-secondary);
    line-height: 1.6;
    animation: slideDown 0.3s ease;
}

.faq-answer[hidden] {
    display: none;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.5);
    z-index: 1000;
    justify-content: center;
    align-items: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    max-width: 500px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
    animation: modalSlideIn 0.3s ease;
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: scale(0.9) translateY(-20px);
    }
    to {
        opacity: 1;
        transform: scale(1) translateY(0);
    }
}

.modal-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.modal-body {
    padding: 1.5rem;
}

.modal-footer {
    padding: 1.5rem;
    border-top: 1px solid var(--border-color);
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
}

.confirm-files {
    background: rgba(244, 67, 54, 0.05);
    border: 1px solid rgba(244, 67, 54, 0.2);
    border-radius: var(--border-radius);
    padding: 1rem;
    margin-top: 1rem;
}

/* Bottom Navigation */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--surface-color);
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-around;
    padding: 0.5rem 0;
    z-index: 100;
    box-shadow: 0 -2px 8px rgba(0,0,0,0.1);
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 0.5rem;
    text-decoration: none;
    color: var(--text-secondary);
    transition: var(--transition);
    border-radius: var(--border-radius);
    min-width: 60px;
}

.nav-item:hover,
.nav-item.active {
    color: var(--primary-color);
    background: rgba(33, 150, 243, 0.1);
}

.nav-item i {
    font-size: 1.2rem;
    margin-bottom: 0.25rem;
}

.nav-item span {
    font-size: 0.75rem;
    font-weight: 500;
}

/* Footer */
footer {
    background: var(--text-primary);
    color: white;
    text-align: center;
    padding: 1rem;
    font-size: 0.9rem;
    margin-top: 2rem;
}

/* Responsive Design */
@media (min-width: 768px) {
    .header-content h1 {
        font-size: 2rem;
    }
    
    .section-header h2 {
        font-size: 2.5rem;
    }
    
    .settings-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .action-buttons {
        justify-content: flex-start;
    }
    
    .action-buttons .btn {
        flex: none;
        min-width: 200px;
    }
    
    .logs-controls {
        justify-content: flex-start;
    }
    
    .logs-controls .btn {
        flex: none;
        min-width: 150px;
    }
    
    .modal-footer .btn {
        flex: none;
        min-width: 120px;
    }
}

@media (min-width: 1024px) {
    .app-main {
        padding: 2rem;
    }
    
    .bottom-nav {
        position: relative;
        background: transparent;
        border: none;
        box-shadow: none;
        justify-content: center;
        gap: 2rem;
        padding: 2rem 0;
    }
    
    .nav-item {
        flex-direction: row;
        gap: 0.5rem;
        padding: 1rem 2rem;
        background: var(--surface-color);
        box-shadow: var(--shadow);
        min-width: auto;
    }
    
    .nav-item i {
        margin-bottom: 0;
    }
    
    .nav-item span {
        font-size: 1rem;
    }
    
    body {
        padding-bottom: 0;
    }
}

/* Loading States */
.loading {
    opacity: 0.6;
    pointer-events: none;
}

.spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 2px solid transparent;
    border-top: 2px solid currentColor;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

/* Utility Classes */
.text-center {
    text-align: center;
}

.text-success {
    color: var(--success-color);
}

.text-danger {
    color: var(--danger-color);
}

.text-warning {
    color: var(--warning-color);
}

.hidden {
    display: none !important;
}

.fade-in {
    animation: fadeIn 0.3s ease-in-out;
}

.slide-up {
    animation: slideUp 0.3s ease-in-out;
}

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