/* ================================================================
   Sprite Sheet Generator — Styles
   Author: Oathan Rex
   Version: 1.0.2
   ================================================================ */

/* ----------------------------------------------------------------
   CSS Custom Properties
   ---------------------------------------------------------------- */
:root {
    /* Colors */
    --color-primary: #2563eb;
    --color-primary-hover: #1d4ed8;
    --color-primary-light: #dbeafe;
    --color-primary-dark: #1e40af;

    --color-secondary: #64748b;
    --color-secondary-hover: #475569;

    --color-success: #16a34a;
    --color-success-light: #dcfce7;
    --color-error: #dc2626;
    --color-error-light: #fee2e2;
    --color-warning: #d97706;
    --color-warning-light: #fef3c7;
    --color-info: #0891b2;
    --color-info-light: #cffafe;

    /* Neutrals */
    --color-white: #ffffff;
    --color-gray-50: #f8fafc;
    --color-gray-100: #f1f5f9;
    --color-gray-200: #e2e8f0;
    --color-gray-300: #cbd5e1;
    --color-gray-400: #94a3b8;
    --color-gray-500: #64748b;
    --color-gray-600: #475569;
    --color-gray-700: #334155;
    --color-gray-800: #1e293b;
    --color-gray-900: #0f172a;

    /* Typography */
    --font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: ui-monospace, 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, monospace;

    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;

    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;

    --line-height-tight: 1.25;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.625;

    /* Spacing */
    --spacing-0: 0;
    --spacing-1: 0.25rem;
    --spacing-2: 0.5rem;
    --spacing-3: 0.75rem;
    --spacing-4: 1rem;
    --spacing-5: 1.25rem;
    --spacing-6: 1.5rem;
    --spacing-8: 2rem;
    --spacing-10: 2.5rem;
    --spacing-12: 3rem;
    --spacing-16: 4rem;

    /* Borders */
    --border-radius-sm: 0.25rem;
    --border-radius: 0.375rem;
    --border-radius-lg: 0.5rem;
    --border-radius-xl: 0.75rem;
    --border-radius-full: 9999px;
    --border-width: 1px;
    --border-color: var(--color-gray-200);

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 200ms ease;
    --transition-slow: 300ms ease;

    /* Layout */
    --max-width: 1400px;
    --header-height: 64px;

    /* Focus */
    --focus-ring: 0 0 0 3px var(--color-primary-light);
    --focus-ring-offset: 0 0 0 2px var(--color-white);
}

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

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
    -webkit-tap-highlight-color: transparent;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
    color: var(--color-gray-800);
    background-color: var(--color-gray-50);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img,
svg {
    display: block;
    max-width: 100%;
    height: auto;
}

button,
input,
select,
textarea {
    font-family: inherit;
    font-size: inherit;
    line-height: inherit;
    margin: 0;
}

button {
    cursor: pointer;
    background: none;
    border: none;
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--color-primary-hover);
}

a:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
    border-radius: var(--border-radius-sm);
}

h1,
h2,
h3,
h4,
h5,
h6 {
    font-weight: var(--font-weight-semibold);
    line-height: var(--line-height-tight);
    color: var(--color-gray-900);
}

ul,
ol {
    list-style: none;
}

/* Utility */
.visually-hidden {
    position: absolute !important;
    width: 1px !important;
    height: 1px !important;
    padding: 0 !important;
    margin: -1px !important;
    overflow: hidden !important;
    clip: rect(0, 0, 0, 0) !important;
    white-space: nowrap !important;
    border: 0 !important;
}

/* ----------------------------------------------------------------
   Header
   ---------------------------------------------------------------- */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--header-height);
    padding: 0 var(--spacing-6);
    background-color: var(--color-white);
    border-bottom: var(--border-width) solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.header-brand {
    display: flex;
    align-items: baseline;
    gap: var(--spacing-3);
    min-width: 0;
}

.header-home {
    display: flex;
    align-items: center;
    color: var(--color-gray-900);
    min-width: 0;
}

.header-home:hover {
    color: var(--color-primary);
}

.tool-name {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.header-byline {
    font-size: var(--font-size-sm);
    color: var(--color-gray-500);
    white-space: nowrap;
}

.header-nav {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    flex-shrink: 0;
}

.nav-link {
    display: flex;
    align-items: center;
    padding: var(--spacing-2) var(--spacing-3);
    color: var(--color-gray-600);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    border-radius: var(--border-radius);
    transition: color var(--transition-fast), background-color var(--transition-fast);
}

.nav-link:hover {
    color: var(--color-gray-900);
    background-color: var(--color-gray-100);
}

.nav-link:focus-visible {
    outline: none;
    box-shadow: var(--focus-ring);
}

.nav-link.nav-icon {
    padding: var(--spacing-2);
}

.nav-link svg {
    width: 20px;
    height: 20px;
    flex-shrink: 0;
}

/* ----------------------------------------------------------------
   Main Content
   ---------------------------------------------------------------- */
.main-content {
    flex: 1;
    width: 100%;
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--spacing-8) var(--spacing-6);
}

/* ----------------------------------------------------------------
   Hero Section
   ---------------------------------------------------------------- */
.hero {
    text-align: center;
    margin-bottom: var(--spacing-8);
}

.hero h1 {
    font-size: var(--font-size-3xl);
    margin-bottom: var(--spacing-3);
}

.hero-subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-gray-600);
    max-width: 700px;
    margin: 0 auto;
}

/* ----------------------------------------------------------------
   App Layout
   ---------------------------------------------------------------- */
.app-layout {
    display: grid;
    grid-template-columns: minmax(300px, 400px) 1fr;
    gap: var(--spacing-6);
    margin-bottom: var(--spacing-12);
    align-items: start;
}

.left-panel,
.right-panel {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-6);
}

.section-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-4);
    margin-bottom: var(--spacing-4);
}

.section-header h2 {
    font-size: var(--font-size-lg);
    margin: 0;
}

.section-hint {
    font-size: var(--font-size-xs);
    color: var(--color-gray-500);
    margin-bottom: var(--spacing-3);
}

/* ----------------------------------------------------------------
   Upload Area
   ---------------------------------------------------------------- */
.upload-section {
    background-color: var(--color-white);
    border: var(--border-width) solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-6);
}

.upload-area {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 200px;
    padding: var(--spacing-8);
    border: 2px dashed var(--color-gray-300);
    border-radius: var(--border-radius-lg);
    background-color: var(--color-gray-50);
    cursor: pointer;
    transition:
        border-color var(--transition-fast),
        background-color var(--transition-fast),
        transform var(--transition-fast);
}

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

.upload-area:focus-visible {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: var(--focus-ring);
}

.upload-area.drag-over {
    border-color: var(--color-primary);
    background-color: var(--color-primary-light);
    border-style: solid;
    transform: scale(1.01);
}

.upload-content {
    text-align: center;
    pointer-events: none;
}

.upload-icon {
    width: 48px;
    height: 48px;
    margin: 0 auto var(--spacing-4);
    color: var(--color-gray-400);
    transition: color var(--transition-fast), transform var(--transition-fast);
}

.upload-area:hover .upload-icon,
.upload-area.drag-over .upload-icon {
    color: var(--color-primary);
    transform: translateY(-2px);
}

.upload-text {
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    color: var(--color-gray-700);
    margin-bottom: var(--spacing-2);
}

.upload-hint {
    font-size: var(--font-size-sm);
    color: var(--color-gray-500);
}

/* ----------------------------------------------------------------
   Images Section
   ---------------------------------------------------------------- */
.images-section {
    background-color: var(--color-white);
    border: var(--border-width) solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-6);
}

.images-section h2 {
    font-size: var(--font-size-lg);
}

.images-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(72px, 1fr));
    gap: var(--spacing-2);
    max-height: 280px;
    overflow-y: auto;
    padding: var(--spacing-1);
}

.image-item {
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--spacing-2);
    border: var(--border-width) solid var(--border-color);
    border-radius: var(--border-radius);
    background-color: var(--color-gray-50);
    cursor: grab;
    user-select: none;
    transition:
        border-color var(--transition-fast),
        box-shadow var(--transition-fast),
        opacity var(--transition-fast),
        transform var(--transition-fast);
}

.image-item:hover {
    border-color: var(--color-gray-400);
    box-shadow: var(--shadow-sm);
}

.image-item:focus-within {
    border-color: var(--color-primary);
    box-shadow: var(--focus-ring);
}

.image-item.dragging {
    opacity: 0.5;
    cursor: grabbing;
    transform: scale(0.95);
}

.image-item.drag-over {
    border-color: var(--color-primary);
    background-color: var(--color-primary-light);
}

.image-preview-wrapper {
    width: 56px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-image:
        linear-gradient(45deg, var(--color-gray-200) 25%, transparent 25%),
        linear-gradient(-45deg, var(--color-gray-200) 25%, transparent 25%),
        linear-gradient(45deg, transparent 75%, var(--color-gray-200) 75%),
        linear-gradient(-45deg, transparent 75%, var(--color-gray-200) 75%);
    background-size: 8px 8px;
    background-position: 0 0, 0 4px, 4px -4px, -4px 0;
    border-radius: var(--border-radius-sm);
    overflow: hidden;
}

.image-preview-wrapper img {
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
}

.image-name {
    font-size: 10px;
    color: var(--color-gray-600);
    text-align: center;
    width: 100%;
    max-width: 64px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    margin-top: var(--spacing-1);
}

.image-remove {
    position: absolute;
    top: -8px;
    right: -8px;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 22px;
    height: 22px;
    padding: 0;
    border: 2px solid var(--color-white);
    border-radius: var(--border-radius-full);
    background-color: var(--color-gray-600);
    color: var(--color-white);
    font-size: 12px;
    cursor: pointer;
    opacity: 0;
    transform: scale(0.8);
    transition:
        opacity var(--transition-fast),
        transform var(--transition-fast),
        background-color var(--transition-fast);
    z-index: 1;
}

.image-item:hover .image-remove,
.image-remove:focus {
    opacity: 1;
    transform: scale(1);
}

.image-remove:hover {
    background-color: var(--color-error);
}

.image-remove:focus-visible {
    outline: none;
    box-shadow: 0 0 0 2px var(--color-white), var(--focus-ring);
    opacity: 1;
    transform: scale(1);
}

.image-remove svg {
    width: 12px;
    height: 12px;
}

/* ----------------------------------------------------------------
   Settings Section
   ---------------------------------------------------------------- */
.settings-section {
    background-color: var(--color-white);
    border: var(--border-width) solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-6);
}

.settings-section>h2 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-5);
}

.setting-group {
    margin-bottom: var(--spacing-5);
}

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

.setting-label {
    display: block;
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    color: var(--color-gray-700);
    margin-bottom: var(--spacing-2);
}

.setting-hint {
    font-size: var(--font-size-xs);
    color: var(--color-gray-500);
    margin-top: var(--spacing-1);
}

.setting-row {
    display: flex;
    align-items: center;
    gap: var(--spacing-3);
}

.setting-range {
    flex: 1;
    height: 6px;
    border-radius: 3px;
    background: var(--color-gray-200);
    appearance: none;
    cursor: pointer;
}

.setting-range::-webkit-slider-thumb {
    appearance: none;
    width: 18px;
    height: 18px;
    border-radius: var(--border-radius-full);
    background: var(--color-primary);
    cursor: pointer;
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.setting-range::-webkit-slider-thumb:hover {
    transform: scale(1.15);
}

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

.setting-range:focus {
    outline: none;
}

.setting-range:focus-visible::-webkit-slider-thumb {
    box-shadow: var(--focus-ring);
}

.setting-number {
    width: 64px;
    padding: var(--spacing-2);
    border: var(--border-width) solid var(--border-color);
    border-radius: var(--border-radius);
    text-align: center;
    font-size: var(--font-size-sm);
    font-family: var(--font-mono);
}

.setting-number:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: var(--focus-ring);
}

.setting-select {
    display: block;
    width: 100%;
    padding: var(--spacing-3) var(--spacing-4);
    padding-right: var(--spacing-8);
    border: var(--border-width) solid var(--border-color);
    border-radius: var(--border-radius);
    background-color: var(--color-white);
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right var(--spacing-3) center;
    color: var(--color-gray-800);
    font-size: var(--font-size-sm);
    cursor: pointer;
    appearance: none;
    transition: border-color var(--transition-fast);
}

.setting-select:hover {
    border-color: var(--color-gray-400);
}

.setting-select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: var(--focus-ring);
}

.setting-custom-width {
    margin-top: var(--spacing-2);
    width: 100%;
}

.setting-text {
    display: block;
    width: 100%;
    padding: var(--spacing-3) var(--spacing-4);
    border: var(--border-width) solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: var(--font-size-sm);
    transition: border-color var(--transition-fast);
}

.setting-text:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: var(--focus-ring);
}

.filename-input-wrapper {
    position: relative;
}

.filename-input-wrapper .setting-text {
    padding-right: 120px;
}

.filename-extension {
    position: absolute;
    right: var(--spacing-3);
    top: 50%;
    transform: translateY(-50%);
    font-size: var(--font-size-xs);
    color: var(--color-gray-400);
    pointer-events: none;
}

.radio-group {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-4);
}

.radio-label {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    font-size: var(--font-size-sm);
    color: var(--color-gray-700);
    cursor: pointer;
}

.radio-label input[type="radio"] {
    width: 16px;
    height: 16px;
    cursor: pointer;
    accent-color: var(--color-primary);
}

.radio-label input[type="radio"]:focus-visible {
    outline: none;
    box-shadow: var(--focus-ring);
    border-radius: var(--border-radius-full);
}

/* ----------------------------------------------------------------
   Preview Section
   ---------------------------------------------------------------- */
.preview-section {
    background-color: var(--color-white);
    border: var(--border-width) solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-6);
    min-height: 450px;
    display: flex;
    flex-direction: column;
}

.preview-info {
    font-size: var(--font-size-sm);
    color: var(--color-gray-500);
    font-family: var(--font-mono);
}

.preview-container {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 350px;
    background-color: var(--color-gray-100);
    background-image:
        linear-gradient(45deg, var(--color-gray-200) 25%, transparent 25%),
        linear-gradient(-45deg, var(--color-gray-200) 25%, transparent 25%),
        linear-gradient(45deg, transparent 75%, var(--color-gray-200) 75%),
        linear-gradient(-45deg, transparent 75%, var(--color-gray-200) 75%);
    background-size: 20px 20px;
    background-position: 0 0, 0 10px, 10px -10px, -10px 0;
    border: var(--border-width) solid var(--border-color);
    border-radius: var(--border-radius);
    overflow: auto;
    position: relative;
}

.preview-empty {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: var(--color-gray-400);
    padding: var(--spacing-8);
}

.preview-empty svg {
    margin-bottom: var(--spacing-4);
    opacity: 0.5;
}

.preview-empty p {
    font-size: var(--font-size-sm);
}

.preview-canvas {
    display: block;
    max-width: 100%;
    max-height: 100%;
    image-rendering: pixelated;
    image-rendering: crisp-edges;
}

.preview-canvas[hidden] {
    display: none;
}

/* ----------------------------------------------------------------
   Export Section
   ---------------------------------------------------------------- */
.export-section {
    background-color: var(--color-white);
    border: var(--border-width) solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-6);
}

.export-section>h2 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-5);
}

.export-buttons {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-3);
}

.export-group {
    display: flex;
    gap: var(--spacing-2);
}

.export-group .btn:first-child {
    flex: 1;
}

/* ----------------------------------------------------------------
   Buttons
   ---------------------------------------------------------------- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-2);
    padding: var(--spacing-3) var(--spacing-5);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    line-height: 1.25;
    border: var(--border-width) solid transparent;
    border-radius: var(--border-radius);
    cursor: pointer;
    white-space: nowrap;
    transition:
        background-color var(--transition-fast),
        border-color var(--transition-fast),
        color var(--transition-fast),
        box-shadow var(--transition-fast),
        transform var(--transition-fast);
}

.btn:focus-visible {
    outline: none;
    box-shadow: var(--focus-ring-offset), var(--focus-ring);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none !important;
}

.btn:active:not(:disabled) {
    transform: translateY(1px);
}

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

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

.btn-secondary {
    background-color: var(--color-white);
    color: var(--color-gray-700);
    border-color: var(--border-color);
}

.btn-secondary:hover:not(:disabled) {
    background-color: var(--color-gray-50);
    border-color: var(--color-gray-300);
}

.btn-sm {
    padding: var(--spacing-2) var(--spacing-3);
    font-size: var(--font-size-xs);
}

.btn-icon {
    padding: var(--spacing-3);
}

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

.btn-with-icon svg {
    width: 16px;
    height: 16px;
    flex-shrink: 0;
}

/* ----------------------------------------------------------------
   Features Section
   ---------------------------------------------------------------- */
.features-section {
    padding-top: var(--spacing-12);
    border-top: var(--border-width) solid var(--border-color);
}

.features-section>h2 {
    font-size: var(--font-size-2xl);
    text-align: center;
    margin-bottom: var(--spacing-10);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: var(--spacing-6);
}

.feature-card {
    padding: var(--spacing-6);
    background-color: var(--color-white);
    border: var(--border-width) solid var(--border-color);
    border-radius: var(--border-radius-lg);
    transition: box-shadow var(--transition-normal), transform var(--transition-normal);
}

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

.feature-card h3 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-3);
}

.feature-card p {
    font-size: var(--font-size-sm);
    color: var(--color-gray-600);
    line-height: var(--line-height-relaxed);
}

/* ----------------------------------------------------------------
   Footer
   ---------------------------------------------------------------- */
.site-footer {
    margin-top: auto;
    padding: var(--spacing-8) var(--spacing-6);
    background-color: var(--color-white);
    border-top: var(--border-width) solid var(--border-color);
    text-align: center;
}

.footer-main {
    margin-bottom: var(--spacing-4);
}

.footer-main p {
    color: var(--color-gray-600);
    font-size: var(--font-size-sm);
}

.footer-main a {
    color: var(--color-gray-800);
    font-weight: var(--font-weight-medium);
}

.privacy-note {
    font-size: var(--font-size-xs) !important;
    color: var(--color-gray-500) !important;
    margin-top: var(--spacing-2);
}

.footer-links {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: var(--spacing-4);
    margin-bottom: var(--spacing-4);
}

.footer-links a {
    font-size: var(--font-size-sm);
    color: var(--color-gray-600);
}

.footer-links a:hover {
    color: var(--color-primary);
}

.version {
    font-size: var(--font-size-xs);
    color: var(--color-gray-400);
    font-family: var(--font-mono);
}

/* ----------------------------------------------------------------
   Toast Notifications
   ---------------------------------------------------------------- */
.toast-container {
    position: fixed;
    bottom: var(--spacing-6);
    right: var(--spacing-6);
    z-index: 1000;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-2);
    pointer-events: none;
    max-width: 360px;
}

.toast {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-3);
    padding: var(--spacing-4);
    background-color: var(--color-gray-800);
    color: var(--color-white);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-lg);
    font-size: var(--font-size-sm);
    line-height: var(--line-height-normal);
    pointer-events: auto;
    cursor: pointer;
    animation: toastIn var(--transition-normal) ease;
}

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

.toast.error {
    background-color: var(--color-error);
}

.toast.warning {
    background-color: var(--color-warning);
}

.toast.info {
    background-color: var(--color-info);
}

.toast.fade-out {
    animation: toastOut var(--transition-normal) ease forwards;
}

@keyframes toastIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }

    to {
        transform: translateX(0);
        opacity: 1;
    }
}

@keyframes toastOut {
    from {
        transform: translateX(0);
        opacity: 1;
    }

    to {
        transform: translateX(100%);
        opacity: 0;
    }
}

/* ----------------------------------------------------------------
   Responsive Design
   ---------------------------------------------------------------- */
@media (max-width: 1024px) {
    .app-layout {
        grid-template-columns: 1fr;
    }

    .preview-section {
        min-height: 400px;
    }
}

@media (max-width: 768px) {
    :root {
        --header-height: 56px;
    }

    .site-header {
        padding: 0 var(--spacing-4);
    }

    .header-brand {
        gap: var(--spacing-2);
    }

    .tool-name {
        font-size: var(--font-size-lg);
    }

    .header-byline {
        display: none;
    }

    .header-nav {
        gap: var(--spacing-1);
    }

    .nav-link:not(.nav-icon) {
        display: none;
    }

    .main-content {
        padding: var(--spacing-6) var(--spacing-4);
    }

    .hero h1 {
        font-size: var(--font-size-2xl);
    }

    .hero-subtitle {
        font-size: var(--font-size-base);
    }

    .upload-area {
        min-height: 160px;
        padding: var(--spacing-6);
    }

    .images-list {
        grid-template-columns: repeat(auto-fill, minmax(64px, 1fr));
        max-height: 220px;
    }

    .preview-container {
        min-height: 280px;
    }

    .export-group {
        flex-direction: column;
    }

    .export-group .btn-icon {
        display: none;
    }

    .toast-container {
        left: var(--spacing-4);
        right: var(--spacing-4);
        bottom: var(--spacing-4);
        max-width: none;
    }
}

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

    .radio-group {
        flex-direction: column;
        gap: var(--spacing-2);
    }
}

/* ----------------------------------------------------------------
   Reduced Motion
   ---------------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {

    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }

    .toast {
        animation: none !important;
    }
}

/* ----------------------------------------------------------------
   Print Styles
   ---------------------------------------------------------------- */
@media print {

    .site-header,
    .site-footer,
    .upload-section,
    .settings-section,
    .export-section,
    .toast-container,
    .features-section {
        display: none !important;
    }

    .app-layout {
        display: block;
    }

    .preview-section {
        border: none;
        padding: 0;
    }
}

/* ----------------------------------------------------------------
   High Contrast Mode
   ---------------------------------------------------------------- */
@media (prefers-contrast: high) {
    :root {
        --border-color: var(--color-gray-600);
    }

    .btn {
        border-width: 2px;
    }

    .upload-area {
        border-width: 3px;
    }
}