:root {
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --success-color: #28a745;
    --error-color: #dc3545;
    --warning-color: #ffc107;
    --info-color: #17a2b8;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    min-height: 100vh;
    padding-top: 60px;
}

/* Back Button */
.back-button {
    position: fixed;
    top: 10px;
    left: 20px;
    background: rgba(255, 255, 255, 0.95);
    color: #333;
    padding: 10px 20px;
    border-radius: 30px;
    text-decoration: none;
    font-weight: 600;
    font-size: 0.95rem;
    border: none;
    cursor: pointer;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    transition: all 0.2s;
}

.back-button:hover {
    background: white;
    transform: translateX(-3px);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.15);
}

/* Breadcrumb */
.breadcrumb-nav {
    max-width: 1000px;
    margin: 0 auto;
    padding: 15px 20px 5px;
}

.breadcrumb {
    list-style: none;
    display: flex;
    gap: 8px;
    font-size: 0.9rem;
}

.breadcrumb li {
    display: flex;
    align-items: center;
    color: rgba(255, 255, 255, 0.9);
}

.breadcrumb li:not(:last-child)::after {
    content: '›';
    margin-left: 8px;
    color: rgba(255, 255, 255, 0.6);
    font-size: 1.2rem;
}

.breadcrumb a {
    color: white;
    text-decoration: none;
    transition: opacity 0.2s;
}

.breadcrumb a:hover {
    opacity: 0.8;
    text-decoration: underline;
}

.breadcrumb [aria-current="page"] {
    color: white;
    font-weight: 600;
}

.container {
    max-width: 1000px;
    margin: 0 auto 40px;
    background: white;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    overflow: hidden;
}

.header {
    background: #2c3e50;
    color: white;
    padding: 25px;
    text-align: center;
}

.header h1 {
    font-size: 2rem;
    margin-bottom: 8px;
}

.header p {
    font-size: 1rem;
    opacity: 0.9;
}

.converter-area {
    padding: 30px;
}

.upload-box {
    border: 3px dashed var(--primary-color);
    border-radius: 10px;
    padding: 50px 20px;
    text-align: center;
    margin-bottom: 25px;
    transition: all 0.2s;
    background: #f8f9fa;
    cursor: pointer;
    position: relative;
}

.upload-box:hover {
    border-color: var(--secondary-color);
    background: #e9ecef;
}

.upload-box.dragover {
    border-color: var(--success-color);
    background: #d4edda;
}

.upload-icon {
    font-size: 3rem;
    margin-bottom: 15px;
    color: var(--primary-color);
    display: block;
}

.upload-box h3 {
    font-size: 1.1rem;
    margin-bottom: 6px;
    color: #333;
}

.upload-box p {
    font-size: 0.9rem;
    color: #666;
    margin-bottom: 4px;
}

.supported-formats {
    font-size: 0.82rem;
    color: #888;
    margin-top: 5px;
}

.browse-button {
    background: var(--primary-color);
    color: white;
    padding: 10px 25px;
    border: none;
    border-radius: 20px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.2s;
    margin-top: 12px;
    font-weight: 600;
    pointer-events: none;
}

#fileInput {
    position: absolute;
    inset: 0;
    opacity: 0;
    cursor: pointer;
    width: 100%;
    height: 100%;
}

.file-info {
    margin-top: 20px;
    padding: 12px;
    background: #e9ecef;
    border-radius: 8px;
    display: none;
    font-size: 0.9rem;
}

.file-info.show {
    display: block;
}

/* Image Gallery Preview */
.image-gallery {
    margin-top: 25px;
    display: none;
}

.image-gallery.show {
    display: block;
}

.gallery-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.gallery-header h3 {
    color: #333;
    font-size: 1.1rem;
}

.gallery-controls {
    display: flex;
    gap: 10px;
}

.gallery-control-btn {
    background: #e9ecef;
    border: none;
    padding: 5px 12px;
    border-radius: 15px;
    cursor: pointer;
    font-size: 0.85rem;
    transition: all 0.2s;
}

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

.gallery-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 15px;
    max-height: 300px;
    overflow-y: auto;
    padding: 5px;
}

.gallery-item {
    position: relative;
    border: 2px solid #ddd;
    border-radius: 8px;
    overflow: hidden;
    cursor: pointer;
    transition: all 0.2s;
    background: white;
}

.gallery-item:hover {
    border-color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

.gallery-item.selected {
    border-color: var(--success-color);
    box-shadow: 0 0 0 3px rgba(40, 167, 69, 0.2);
}

.gallery-item-image {
    width: 100%;
    height: 120px;
    object-fit: cover;
    display: block;
}

.gallery-item-info {
    padding: 8px;
    background: #f8f9fa;
}

.gallery-item-name {
    font-size: 0.75rem;
    font-weight: 600;
    margin-bottom: 3px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.gallery-item-size {
    font-size: 0.7rem;
    color: #666;
}

.gallery-item-badge {
    position: absolute;
    top: 5px;
    right: 5px;
    background: var(--primary-color);
    color: white;
    padding: 2px 6px;
    border-radius: 10px;
    font-size: 0.65rem;
    font-weight: 600;
}

.gallery-item-remove {
    position: absolute;
    top: 5px;
    left: 5px;
    background: rgba(220, 53, 69, 0.9);
    color: white;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 0.8rem;
    opacity: 0;
    transition: opacity 0.2s;
}

.gallery-item:hover .gallery-item-remove {
    opacity: 1;
}

.conversion-options {
    background: #f8f9fa;
    padding: 25px;
    border-radius: 10px;
    margin: 25px 0;
    display: none;
}

.conversion-options.show {
    display: block;
}

.format-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
    margin-top: 20px;
}

.format-option {
    border: 2px solid #ddd;
    border-radius: 10px;
    padding: 20px;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s;
    background: white;
}

.format-option:hover:not(.disabled) {
    border-color: var(--primary-color);
    transform: translateY(-2px);
}

.format-option.selected {
    border-color: var(--success-color);
    background: #d4edda;
}

.format-option.disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.format-icon {
    font-size: 2.5rem;
    margin-bottom: 10px;
}

.format-name {
    font-weight: 600;
    margin-bottom: 5px;
    color: #333;
}

.format-desc {
    font-size: 0.8rem;
    color: #666;
    margin-bottom: 10px;
}

.format-specs {
    font-size: 0.75rem;
    color: #888;
}

.quality-controls {
    margin-top: 25px;
    padding-top: 20px;
    border-top: 1px solid #eee;
}

.control-group {
    margin-bottom: 20px;
}

.control-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: #333;
    font-size: 0.95rem;
}

.quality-slider {
    width: 100%;
    margin: 10px 0;
    -webkit-appearance: none;
    height: 6px;
    border-radius: 3px;
    background: #ddd;
    outline: none;
    cursor: pointer;
}

.quality-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
}

.quality-slider::-moz-range-thumb {
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    border: none;
}

.slider-labels {
    display: flex;
    justify-content: space-between;
    margin-top: 5px;
    font-size: 0.85rem;
    color: #666;
}

.control-input {
    width: 100%;
    padding: 10px;
    border-radius: 5px;
    border: 1px solid #ddd;
    font-size: 0.95rem;
    transition: border-color 0.2s;
    outline: none;
}

.control-input:focus {
    border-color: var(--primary-color);
}

.preview-comparison {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
    margin: 25px 0;
    display: none;
}

.preview-comparison.show {
    display: grid;
}

.preview-box {
    text-align: center;
    padding: 12px;
    background: #f8f9fa;
    border-radius: 8px;
}

.preview-box h3 {
    margin-bottom: 12px;
    color: #333;
    font-size: 1rem;
}

.preview-image {
    max-width: 100%;
    max-height: 250px;
    border-radius: 6px;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.1);
    object-fit: contain;
}

.file-stats {
    margin-top: 8px;
    font-size: 0.85rem;
    color: #666;
}

.convert-button {
    background: var(--success-color);
    color: white;
    padding: 12px 30px;
    border: none;
    border-radius: 20px;
    font-size: 1.1rem;
    cursor: pointer;
    width: 100%;
    margin-top: 15px;
    font-weight: 600;
    transition: all 0.2s;
}

.convert-button:hover:not(:disabled) {
    background: #218838;
    transform: translateY(-2px);
}

.convert-button:disabled {
    background: #6c757d;
    cursor: not-allowed;
}

.convert-button.loading {
    opacity: 0.7;
    pointer-events: none;
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: #e9ecef;
    border-radius: 4px;
    margin: 15px 0;
    overflow: hidden;
    display: none;
}

.progress-bar.show {
    display: block;
}

.progress-fill {
    height: 100%;
    background: var(--success-color);
    border-radius: 4px;
    transition: width 0.3s ease;
    width: 0%;
}

.message {
    padding: 12px;
    border-radius: 6px;
    margin-top: 15px;
    font-size: 0.9rem;
    display: none;
}

.message.show {
    display: block;
}

.error-message {
    background: #f8d7da;
    color: var(--error-color);
    border: 1px solid #f5c6cb;
}

.warning-message {
    background: #fff3cd;
    color: #856404;
    border: 1px solid #ffeaa7;
}

.info-message {
    background: #d1ecf1;
    color: #0c5460;
    border: 1px solid #bee5eb;
}

.result-area {
    margin-top: 25px;
    padding: 20px;
    background: #d4edda;
    border-radius: 10px;
    text-align: center;
    display: none;
}

.result-area.show {
    display: block;
}

.result-area h3 {
    color: var(--success-color);
    margin-bottom: 10px;
}

.conversion-info {
    font-size: 1.1rem;
    font-weight: bold;
    margin: 12px 0;
}

.action-button {
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 20px;
    display: inline-block;
    margin: 8px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 600;
    transition: all 0.2s;
}

.download-button {
    background: var(--success-color);
}

.download-button:hover {
    background: #218838;
    transform: translateY(-2px);
}

.new-conversion-button {
    background: var(--primary-color);
}

.new-conversion-button:hover {
    background: #5a6fd8;
    transform: translateY(-2px);
}

.batch-download-button {
    background: var(--info-color);
}

.batch-download-button:hover {
    background: #138496;
    transform: translateY(-2px);
}

.batch-results {
    margin-top: 20px;
    display: none;
}

.batch-results.show {
    display: block;
}

.batch-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 15px;
    margin-top: 15px;
}

.batch-item {
    text-align: center;
    padding: 15px;
    background: white;
    border-radius: 8px;
    border: 1px solid #ddd;
    cursor: pointer;
    transition: all 0.2s;
}

.batch-item:hover {
    border-color: var(--primary-color);
    transform: translateY(-2px);
}

.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 15px;
    margin-top: 30px;
    padding: 25px;
    background: #f8f9fa;
    border-radius: 10px;
}

.feature {
    text-align: center;
    padding: 15px;
}

.feature-icon {
    font-size: 2rem;
    margin-bottom: 10px;
}

.feature h4 {
    margin-bottom: 8px;
    font-size: 1rem;
    color: #333;
}

.feature p {
    font-size: 0.9rem;
    color: #555;
}

.seo-content {
    padding: 30px;
    border-top: 1px solid #eee;
}

.seo-content h2 {
    font-size: 1.2rem;
    color: #2c3e50;
    margin: 20px 0 8px;
}

.seo-content h2:first-child {
    margin-top: 0;
}

.seo-content p {
    font-size: 0.95rem;
    color: #555;
    line-height: 1.7;
}

.faq-section {
    padding: 30px;
    background: #f8f9fa;
    border-top: 1px solid #eee;
}

.faq-section h2 {
    text-align: center;
    margin-bottom: 24px;
    color: #333;
    font-size: 1.5rem;
}

.faq-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 16px;
}

.faq-item {
    background: white;
    padding: 15px 20px;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05);
}

.faq-item summary {
    font-weight: 600;
    color: #333;
    cursor: pointer;
    padding: 5px 0;
}

.faq-item summary:hover {
    color: var(--primary-color);
}

.faq-item p {
    margin-top: 10px;
    color: #555;
    line-height: 1.6;
    font-size: 0.95rem;
}

.related-tools {
    padding: 30px;
    text-align: center;
    border-top: 1px solid #eee;
}

.related-tools h2 {
    margin-bottom: 20px;
    color: #333;
    font-size: 1.4rem;
}

.related-links {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 12px;
}

.related-link {
    display: inline-block;
    padding: 10px 20px;
    background: #e9ecef;
    color: #333;
    text-decoration: none;
    border-radius: 25px;
    font-weight: 500;
    font-size: 0.9rem;
    transition: all 0.2s;
}

.related-link:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-2px);
}

footer {
    background: #2c3e50;
    color: white;
    padding: 20px;
    text-align: center;
    font-size: 0.9rem;
}

footer a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
}

footer a:hover {
    color: white;
    text-decoration: underline;
}

/* Tool Switcher */
.tool-switcher {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
    background: rgba(255, 255, 255, 0.12);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 14px;
    padding: 10px 16px;
    margin: 0 auto 16px;
    max-width: 1000px;
}

.tool-switcher-label {
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-right: 4px;
    white-space: nowrap;
}

.tool-switch-btn {
    color: rgba(255, 255, 255, 0.85);
    text-decoration: none;
    font-size: 0.85rem;
    font-weight: 500;
    padding: 6px 14px;
    border-radius: 20px;
    border: 1px solid rgba(255, 255, 255, 0.2);
    background: rgba(255, 255, 255, 0.1);
    transition: all 0.2s;
    white-space: nowrap;
    display: inline-block;
}

.tool-switch-btn:hover {
    background: rgba(255, 255, 255, 0.25);
    color: white;
}

.tool-switch-btn.active {
    background: white;
    color: #667eea;
    font-weight: 700;
    border-color: white;
    pointer-events: none;
}

@media (max-width: 600px) {
    .tool-switcher {
        gap: 6px;
        padding: 8px 12px;
    }

    .tool-switch-btn {
        font-size: 0.78rem;
        padding: 5px 10px;
    }
}

@media (max-width: 768px) {
    body {
        padding-top: 50px;
    }

    .back-button {
        top: 8px;
        left: 10px;
        padding: 8px 16px;
        font-size: 0.85rem;
    }

    .header h1 {
        font-size: 1.6rem;
    }

    .converter-area {
        padding: 20px;
    }

    .upload-box {
        padding: 30px 15px;
    }

    .preview-comparison {
        grid-template-columns: 1fr;
    }

    .format-grid {
        grid-template-columns: 1fr;
    }

    .faq-grid {
        grid-template-columns: 1fr;
    }

    .features {
        grid-template-columns: 1fr 1fr;
        padding: 20px 15px;
    }

    .gallery-grid {
        grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    }
}

@media (max-width: 480px) {
    .features {
        grid-template-columns: 1fr;
    }

    .related-links {
        flex-direction: column;
        align-items: stretch;
    }

    .related-link {
        text-align: center;
    }

    .action-button {
        display: block;
        width: 100%;
        margin: 8px 0;
    }
}