/* CSS Reset and Base Styles */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --primary-light: #e0e7ff;
    --secondary-color: #8b5cf6;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-light: #9ca3af;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --border-color: #e5e7eb;
    --border-hover: #d1d5db;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px 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);
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --transition: 150ms ease;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: linear-gradient(135deg, #f5f7fa 0%, #e4e8ec 100%);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1.5rem;
}

/* Header */
header {
    text-align: center;
    margin-bottom: 3rem;
}

.logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 0.75rem;
}

.logo h1 {
    font-size: 2rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

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

/* Sections */
section {
    background: var(--bg-primary);
    border-radius: var(--radius-xl);
    padding: 2rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow-md);
}

section h2 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

section h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Drop Zone */
.drop-zone {
    border: 2px dashed var(--border-color);
    border-radius: var(--radius-lg);
    padding: 3rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all var(--transition);
    background: var(--bg-secondary);
}

.drop-zone:hover,
.drop-zone.drag-over {
    border-color: var(--primary-color);
    background: var(--primary-light);
}

.drop-zone.drag-over {
    transform: scale(1.01);
}

.drop-zone-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.75rem;
}

.upload-icon {
    color: var(--text-light);
    margin-bottom: 0.5rem;
}

.drop-text {
    font-size: 1.25rem;
    font-weight: 500;
    color: var(--text-primary);
}

.drop-subtext {
    color: var(--text-light);
}

.browse-btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    background: var(--primary-color);
    color: white;
    border-radius: var(--radius-md);
    font-weight: 500;
    cursor: pointer;
    transition: background var(--transition);
}

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

.file-types {
    font-size: 0.875rem;
    color: var(--text-light);
    margin-top: 0.5rem;
}

/* Preview Section */
.preview-section .preview-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.preview-section .preview-header h2 {
    margin-bottom: 0;
}

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

#previewImage {
    max-width: 100%;
    max-height: 300px;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
    object-fit: contain;
    background: repeating-conic-gradient(#f3f4f6 0% 25%, transparent 0% 50%) 50% / 20px 20px;
}

.image-info {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    justify-content: center;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.image-info span {
    background: var(--bg-tertiary);
    padding: 0.375rem 0.75rem;
    border-radius: var(--radius-sm);
}

/* Preset Categories */
.preset-categories {
    display: grid;
    gap: 1.5rem;
    margin-bottom: 1.5rem;
}

.preset-category {
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    padding: 1.25rem;
}

.preset-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.preset-btn {
    padding: 0.5rem 1rem;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-primary);
    cursor: pointer;
    transition: all var(--transition);
}

.preset-btn:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

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

/* Quick Actions */
.quick-actions {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

/* Custom Size */
.custom-size {
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    padding: 1.25rem;
    margin-bottom: 1.5rem;
}

.custom-size-inputs {
    display: flex;
    align-items: flex-end;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 0.375rem;
    position: relative;
}

.input-group label {
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.input-group input[type="number"] {
    width: 100px;
    padding: 0.625rem 2rem 0.625rem 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 0.9375rem;
    transition: border-color var(--transition);
}

.input-group input[type="number"]:focus {
    outline: none;
    border-color: var(--primary-color);
}

.input-group .unit {
    position: absolute;
    right: 0.75rem;
    bottom: 0.625rem;
    font-size: 0.875rem;
    color: var(--text-light);
}

.dimension-separator {
    font-size: 1.25rem;
    color: var(--text-light);
    margin-bottom: 0.5rem;
}

.lock-btn {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    cursor: pointer;
    color: var(--text-secondary);
    transition: all var(--transition);
}

.lock-btn:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.lock-btn.active {
    background: var(--primary-light);
    border-color: var(--primary-color);
    color: var(--primary-color);
}

/* Selected Sizes */
.selected-sizes {
    margin-bottom: 1.5rem;
}

.selected-sizes h3 span {
    font-weight: 400;
    color: var(--text-light);
}

.sizes-list {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    min-height: 48px;
    padding: 1rem;
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
}

.sizes-list .no-sizes {
    color: var(--text-light);
    font-size: 0.875rem;
    width: 100%;
    text-align: center;
}

.size-tag {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 0.75rem;
    background: var(--primary-color);
    color: white;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    font-weight: 500;
}

.size-tag .remove-size {
    background: none;
    border: none;
    color: white;
    cursor: pointer;
    padding: 0;
    display: flex;
    align-items: center;
    opacity: 0.7;
    transition: opacity var(--transition);
}

.size-tag .remove-size:hover {
    opacity: 1;
}

/* Output Options */
.output-options {
    margin-bottom: 1.5rem;
}

.options-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    background: var(--bg-secondary);
    padding: 1.25rem;
    border-radius: var(--radius-md);
}

.option-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.option-group label {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
}

.option-group select {
    padding: 0.625rem 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 0.9375rem;
    background: var(--bg-primary);
    cursor: pointer;
}

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

.quality-group {
    flex-direction: row;
    align-items: center;
    flex-wrap: wrap;
}

.quality-group label {
    flex-shrink: 0;
}

.quality-group input[type="range"] {
    flex: 1;
    min-width: 100px;
    height: 6px;
    -webkit-appearance: none;
    background: var(--bg-tertiary);
    border-radius: 3px;
    cursor: pointer;
}

.quality-group input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 18px;
    height: 18px;
    background: var(--primary-color);
    border-radius: 50%;
    cursor: pointer;
}

.quality-group #qualityValue {
    font-weight: 600;
    color: var(--primary-color);
    min-width: 40px;
    text-align: right;
}

.option-group label:has(input[type="checkbox"]) {
    flex-direction: row;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
}

.option-group input[type="checkbox"] {
    width: 18px;
    height: 18px;
    accent-color: var(--primary-color);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.625rem 1.25rem;
    border: none;
    border-radius: var(--radius-md);
    font-size: 0.9375rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition);
}

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

.btn-primary:hover:not(:disabled) {
    background: var(--primary-hover);
}

.btn-primary:disabled {
    background: var(--text-light);
    cursor: not-allowed;
}

.btn-secondary {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

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

.btn-outline {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.btn-outline:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.btn-large {
    padding: 1rem 2rem;
    font-size: 1.0625rem;
}

/* Generate Section */
.generate-section {
    text-align: center;
}

/* Results Section */
.results-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.result-item {
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    padding: 1rem;
    text-align: center;
    transition: transform var(--transition);
}

.result-item:hover {
    transform: translateY(-2px);
}

.result-item img {
    max-width: 100%;
    max-height: 120px;
    border-radius: var(--radius-sm);
    margin-bottom: 0.75rem;
    background: repeating-conic-gradient(#e5e7eb 0% 25%, white 0% 50%) 50% / 10px 10px;
}

.result-item .size-label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.result-item .file-size {
    font-size: 0.75rem;
    color: var(--text-light);
    margin-bottom: 0.75rem;
}

.result-item .download-btn {
    width: 100%;
}

.download-all {
    text-align: center;
}

/* Loading Overlay */
.loading-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;
}

.loading-content {
    background: var(--bg-primary);
    padding: 2.5rem 3rem;
    border-radius: var(--radius-xl);
    text-align: center;
    box-shadow: var(--shadow-lg);
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid var(--bg-tertiary);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    margin: 0 auto 1.5rem;
    animation: spin 1s linear infinite;
}

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

.progress-bar {
    width: 200px;
    height: 8px;
    background: var(--bg-tertiary);
    border-radius: 4px;
    margin: 1rem auto;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    border-radius: 4px;
    transition: width 100ms ease;
    width: 0%;
}

#progressText {
    font-weight: 600;
    color: var(--primary-color);
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem 1rem;
    color: var(--text-light);
    font-size: 0.875rem;
}

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

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }

    header {
        margin-bottom: 2rem;
    }

    .logo h1 {
        font-size: 1.5rem;
    }

    .tagline {
        font-size: 0.9375rem;
    }

    section {
        padding: 1.5rem;
    }

    .drop-zone {
        padding: 2rem 1rem;
    }

    .drop-text {
        font-size: 1rem;
    }

    .custom-size-inputs {
        flex-direction: column;
        align-items: stretch;
    }

    .custom-size-inputs .input-group {
        width: 100%;
    }

    .custom-size-inputs .input-group input[type="number"] {
        width: 100%;
    }

    .dimension-separator {
        display: none;
    }

    .lock-btn {
        width: 100%;
    }

    .custom-size-inputs #addCustomSize {
        width: 100%;
    }

    .quick-actions {
        flex-direction: column;
    }

    .quick-actions .btn {
        width: 100%;
    }

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

    .quality-group {
        flex-direction: column;
        align-items: stretch;
    }

    .quality-group input[type="range"] {
        width: 100%;
    }

    .results-grid {
        grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    }

    .btn-large {
        width: 100%;
        padding: 0.875rem 1.5rem;
    }

    .loading-content {
        padding: 2rem;
        margin: 1rem;
    }
}

@media (max-width: 480px) {
    .logo svg {
        width: 32px;
        height: 32px;
    }

    .logo h1 {
        font-size: 1.25rem;
    }

    .preset-btn {
        padding: 0.375rem 0.75rem;
        font-size: 0.8125rem;
    }

    .results-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Print Styles */
@media print {
    .upload-section,
    .generate-section,
    .download-all,
    .loading-overlay {
        display: none;
    }
}