/* CSS Custom Properties for easy theming */
:root {
    --color-bg: #f8f9fa;
    --color-surface: #ffffff;
    --color-text: #212529;
    --color-text-muted: #6c757d;
    --color-primary: #4361ee;
    --color-primary-hover: #3a56d4;
    --color-border: #dee2e6;
    --color-border-hover: #adb5bd;
    --color-success: #28a745;
    --color-error: #dc3545;
    --color-output-bg: #1e1e1e;
    --color-output-text: #d4d4d4;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --transition: 0.2s ease;
    --max-width: 900px;
}

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

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    min-height: 100vh;
}

/* Container */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 2rem 1rem;
}

/* Header */
header {
    text-align: center;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 2rem;
    font-weight: 700;
    margin: 0 0 0.5rem;
    color: var(--color-text);
}

.subtitle {
    color: var(--color-text-muted);
    font-size: 1rem;
    margin: 0;
    max-width: 500px;
    margin: 0 auto;
}

/* Sections */
section {
    background: var(--color-surface);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow-sm);
}

section h2 {
    font-size: 1.1rem;
    font-weight: 600;
    margin: 0 0 1rem;
    color: var(--color-text);
}

/* Upload Zone */
.upload-section {
    padding: 0;
    background: transparent;
    box-shadow: none;
}

.upload-zone {
    border: 2px dashed var(--color-border);
    border-radius: var(--radius-lg);
    padding: 3rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all var(--transition);
    background: var(--color-surface);
}

.upload-zone:hover,
.upload-zone.drag-over {
    border-color: var(--color-primary);
    background: rgba(67, 97, 238, 0.05);
}

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

.upload-icon {
    width: 48px;
    height: 48px;
    color: var(--color-text-muted);
    margin-bottom: 1rem;
}

.upload-text {
    font-size: 1.1rem;
    font-weight: 500;
    margin: 0 0 0.5rem;
    color: var(--color-text);
}

.upload-hint {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    margin: 0;
}

/* Image Preview */
.preview-section {
    text-align: center;
}

.image-preview-container {
    max-width: 100%;
    overflow: hidden;
    border-radius: var(--radius-md);
    background: var(--color-bg);
}

.image-preview-container img {
    max-width: 100%;
    max-height: 300px;
    object-fit: contain;
    display: block;
    margin: 0 auto;
}

/* Controls */
.control-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.control-group label {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--color-text);
}

.control-group label span {
    color: var(--color-primary);
    font-weight: 600;
}

/* Range Slider */
input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 8px;
    background: var(--color-bg);
    border-radius: var(--radius-sm);
    outline: none;
    cursor: pointer;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    background: var(--color-primary);
    border-radius: 50%;
    cursor: pointer;
    transition: transform var(--transition), box-shadow var(--transition);
}

input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.1);
    box-shadow: 0 0 0 4px rgba(67, 97, 238, 0.2);
}

input[type="range"]::-moz-range-thumb {
    width: 20px;
    height: 20px;
    background: var(--color-primary);
    border-radius: 50%;
    cursor: pointer;
    border: none;
}

/* Output Section */
.output-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
    margin-bottom: 1rem;
}

.output-header h2 {
    margin: 0;
}

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

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.6rem 1rem;
    font-size: 0.9rem;
    font-weight: 500;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition);
}

.btn svg {
    width: 16px;
    height: 16px;
}

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

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

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

.btn-download {
    background: var(--color-surface);
    color: var(--color-text);
    border: 1px solid var(--color-border);
}

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

.btn-invert {
    background: var(--color-surface);
    color: var(--color-text);
    border: 1px solid var(--color-border);
}

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

.btn-invert.active {
    background: var(--color-text);
    color: var(--color-surface);
    border-color: var(--color-text);
}

/* Output Container */
.output-container {
    background: var(--color-output-bg);
    border-radius: var(--radius-md);
    padding: 1rem;
    overflow: auto;
    min-height: 200px;
    max-height: 80vh;
    height: 500px;
    resize: both;
    transition: background-color 0.2s ease, color 0.2s ease;
}

.output-container.inverted {
    background: #f5f5f5;
}

.output-container pre {
    margin: 0;
    font-family: 'SF Mono', 'Fira Code', 'Consolas', 'Monaco', monospace;
    font-size: 8px;
    line-height: 1.1;
    color: var(--color-output-text);
    white-space: pre;
    tab-size: 4;
    width: fit-content;
    transition: color 0.2s ease;
}

.output-container.inverted pre {
    color: #1e1e1e;
}

/* Loading Indicator */
.loading {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.9);
    display: none;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    z-index: 1000;
}

.loading:not([hidden]) {
    display: flex;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--color-border);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

.loading p {
    margin: 0;
    font-weight: 500;
    color: var(--color-text-muted);
}

/* Error Message */
.error-message {
    background: rgba(220, 53, 69, 0.1);
    border: 1px solid var(--color-error);
    color: var(--color-error);
    padding: 1rem;
    border-radius: var(--radius-md);
    margin-bottom: 1.5rem;
    text-align: center;
}

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

    header h1 {
        font-size: 1.5rem;
    }

    .subtitle {
        font-size: 0.9rem;
    }

    section {
        padding: 1rem;
    }

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

    .upload-icon {
        width: 36px;
        height: 36px;
    }

    .output-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .action-buttons {
        width: 100%;
    }

    .btn {
        flex: 1;
        justify-content: center;
    }

    .output-container pre {
        font-size: 6px;
    }
}

@media (max-width: 480px) {
    header h1 {
        font-size: 1.3rem;
    }

    .action-buttons {
        flex-direction: column;
    }

    .btn {
        width: 100%;
    }

    .output-container pre {
        font-size: 5px;
    }
}

/* Accessibility - Focus States */
:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.upload-zone:focus-visible {
    border-color: var(--color-primary);
    box-shadow: 0 0 0 4px rgba(67, 97, 238, 0.2);
}

/* Print Styles */
@media print {
    .upload-section,
    .controls-section,
    .action-buttons,
    footer {
        display: none;
    }

    .output-container {
        max-height: none;
        overflow: visible;
    }
}