:root {
    --bg-primary: #0f172a;
    --bg-surface: #1e293b;
    --bg-card: #334155;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-blue: #38bdf8;
    --accent-blue-hover: #0284c7;
    --accent-green: #22c55e;
    --accent-green-hover: #16a34a;
    --border-color: #475569;
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.3), 0 4px 6px -4px rgba(0, 0, 0, 0.2);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    padding: 24px;
    line-height: 1.5;
}

.app-container {
    max-width: 1280px;
    margin: 0 auto;
}

.app-content {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

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

/* Header */
.app-header {
    margin-bottom: 8px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 16px;
    flex-wrap: wrap;
}

.header-brand {
    display: flex;
    align-items: center;
    gap: 16px;
}

.header-icon {
    width: 36px;
    height: 36px;
    color: var(--accent-blue);
    flex-shrink: 0;
}

.app-header h1 {
    font-size: 1.75rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

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

/* Panels / steps */
.panel-card {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 24px;
    box-shadow: var(--shadow);
}

.card-header {
    display: flex;
    align-items: flex-start;
    gap: 14px;
    margin-bottom: 20px;
}

.card-header-text {
    flex: 1;
    min-width: 0;
}

.card-header h2 {
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--text-primary);
    line-height: 1.3;
}

.card-header h3,
.resize-preview-header h3,
.content-block h2 {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-primary);
}

.step-index {
    flex-shrink: 0;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: rgba(56, 189, 248, 0.15);
    border: 1px solid var(--accent-blue);
    color: var(--accent-blue);
    font-size: 0.9rem;
    font-weight: 700;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    margin-top: 2px;
}

.step-desc {
    margin-top: 4px;
    color: var(--text-secondary);
    font-size: 0.88rem;
}

.inline-warning {
    display: inline-flex;
    align-items: flex-start;
    gap: 6px;
    margin-left: 8px;
    padding: 4px 10px;
    border-radius: var(--radius-sm);
    background: rgba(245, 158, 11, 0.12);
    border: 1px solid rgba(245, 158, 11, 0.55);
    color: #fbbf24;
    font-size: 0.82rem;
    font-weight: 600;
    text-transform: none;
    letter-spacing: normal;
    line-height: 1.35;
    vertical-align: middle;
    max-width: 100%;
}

.inline-warning.hidden {
    display: none;
}

.inline-warning-icon {
    flex-shrink: 0;
    line-height: 1.35;
}

.inline-warning-text {
    font-weight: 500;
}

/* Forms */
.form-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.form-group.hidden {
    display: none !important;
}

label {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.label-spacer {
    visibility: hidden;
    user-select: none;
}

input[type="text"],
input[type="number"] {
    width: 100%;
    padding: 12px 16px;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 0.95rem;
    outline: none;
    transition: border-color 0.2s, box-shadow 0.2s;
}

input[type="text"]:focus,
input[type="number"]:focus {
    border-color: var(--accent-blue);
    box-shadow: 0 0 0 3px rgba(56, 189, 248, 0.2);
}

.source-actions,
.export-actions {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
    align-items: stretch;
}

.load-summary {
    margin-top: 12px;
    color: var(--text-secondary);
    font-size: 0.88rem;
}

.load-summary.hidden {
    display: none;
}

/* Resize mode + value + preview row */
.mode-selector {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

@media (max-width: 640px) {
    .mode-selector {
        grid-template-columns: 1fr;
    }
}

.mode-option input[type="radio"] {
    display: none;
}

.mode-card {
    display: flex;
    flex-direction: column;
    padding: 14px;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all 0.2s;
    height: 100%;
}

.mode-card strong {
    font-size: 0.95rem;
    color: var(--text-primary);
}

.mode-card small {
    font-size: 0.78rem;
    color: var(--text-secondary);
    margin-top: 2px;
}

.mode-option input[type="radio"]:checked + .mode-card {
    border-color: var(--accent-blue);
    background: rgba(56, 189, 248, 0.1);
    box-shadow: 0 0 0 1px var(--accent-blue);
}

.resize-controls {
    display: grid;
    grid-template-columns: minmax(160px, 240px) auto;
    gap: 16px;
    align-items: end;
    margin-top: 18px;
}

@media (max-width: 640px) {
    .resize-controls {
        grid-template-columns: 1fr;
    }

    .resize-preview-action .label-spacer {
        display: none;
    }
}

.resize-preview-action .btn {
    width: 100%;
    min-width: 140px;
}

.resize-preview-block {
    margin-top: 20px;
    padding-top: 20px;
    border-top: 1px solid var(--border-color);
}

.resize-preview-block.hidden {
    display: none;
}

.resize-preview-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
    margin-bottom: 12px;
}

.resize-preview-frame {
    position: relative;
    display: inline-block;
    max-width: 100%;
    overflow: auto;
    background:
        linear-gradient(45deg, #1e293b 25%, transparent 25%),
        linear-gradient(-45deg, #1e293b 25%, transparent 25%),
        linear-gradient(45deg, transparent 75%, #1e293b 75%),
        linear-gradient(-45deg, transparent 75%, #1e293b 75%);
    background-size: 20px 20px;
    background-position: 0 0, 0 10px, 10px -10px, -10px 0;
    background-color: #0f172a;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    line-height: 0;
}

.resize-preview-frame img {
    display: block;
    max-width: none;
    height: auto;
    image-rendering: auto;
}

.preview-size-overlay {
    pointer-events: none;
}

.preview-hint {
    margin-top: 12px;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.resize-limit-note {
    margin-top: 12px;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* Buttons */
.btn {
    padding: 12px 20px;
    font-size: 0.95rem;
    font-weight: 600;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: background-color 0.2s, transform 0.1s, opacity 0.2s, border-color 0.2s, color 0.2s;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    white-space: nowrap;
}

.btn:active {
    transform: scale(0.98);
}

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

.btn-primary {
    background: var(--accent-blue);
    color: #0f172a;
}

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

.btn-success {
    background: var(--accent-green);
    color: #0f172a;
}

.btn-success:hover:not(:disabled) {
    background: var(--accent-green-hover);
    color: #ffffff;
}

.btn-secondary {
    background: var(--bg-card);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover:not(:disabled) {
    border-color: var(--accent-blue);
    color: var(--accent-blue);
}

/* Status Banner */
.status-banner {
    padding: 14px 18px;
    border-radius: var(--radius-md);
    font-size: 0.9rem;
}

.status-banner.hidden {
    display: none;
}

.status-banner.success {
    background: rgba(34, 197, 94, 0.15);
    border: 1px solid var(--accent-green);
    color: #4ade80;
}

.status-banner.error {
    background: rgba(239, 68, 68, 0.15);
    border: 1px solid #ef4444;
    color: #fca5a5;
}

.status-banner.info {
    background: rgba(56, 189, 248, 0.15);
    border: 1px solid var(--accent-blue);
    color: #7dd3fc;
}

/* Gallery */
.gallery-section .card-header.gallery-header {
    align-items: center;
}

.gallery-header .badge {
    flex-shrink: 0;
}

.badge {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
}

.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 48px 20px;
    color: var(--text-secondary);
    text-align: center;
}

.empty-icon {
    width: 48px;
    height: 48px;
    margin-bottom: 12px;
    opacity: 0.5;
}

.image-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 20px;
}

.image-grid.hidden {
    display: none;
}

.thumbnail-card {
    position: relative;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    overflow: hidden;
    aspect-ratio: 4 / 3;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: transform 0.2s, box-shadow 0.2s;
}

.thumbnail-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 20px -5px rgba(0, 0, 0, 0.5);
    border-color: var(--accent-blue);
}

.thumbnail-card img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.overlay {
    position: absolute;
    background: rgba(15, 23, 42, 0.85);
    color: var(--text-primary);
    backdrop-filter: blur(4px);
    border-radius: var(--radius-sm);
    padding: 4px 8px;
    font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
    font-size: 0.75rem;
    pointer-events: none;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.4);
    z-index: 10;
}

.overlay-top-left {
    top: 8px;
    left: 8px;
    max-width: calc(100% - 16px);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.overlay-bottom-left {
    bottom: 8px;
    left: 8px;
    color: #4ade80;
    font-weight: 600;
    border: 1px solid rgba(74, 222, 128, 0.2);
}

/* Export progress */
.export-progress {
    margin-top: 16px;
}

.export-progress.hidden {
    display: none;
}

.progress-track {
    width: 100%;
    height: 10px;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 999px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    width: 0;
    background: var(--accent-green);
    transition: width 0.15s ease-out;
}

.progress-text {
    display: block;
    margin-top: 8px;
    color: var(--text-secondary);
    font-size: 0.85rem;
}

/* Content / docs on the tool page */
.content-block {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.content-block h2 {
    font-size: 1.15rem;
    margin-bottom: 10px;
}

.content-block h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin: 16px 0 8px;
}

.content-block p,
.content-block li {
    margin-bottom: 8px;
}

.content-block ol,
.content-block ul {
    padding-left: 1.25rem;
    margin-bottom: 8px;
}

.content-block a {
    color: var(--accent-blue);
    text-decoration: none;
}

.content-block a:hover {
    text-decoration: underline;
}

.privacy-callout {
    margin-top: 12px;
    padding: 14px 16px;
    border-radius: var(--radius-md);
    background: rgba(56, 189, 248, 0.1);
    border: 1px solid var(--accent-blue);
    color: #e0f2fe;
    font-weight: 500;
}

.faq-item {
    margin-top: 14px;
}

.faq-item h3 {
    margin-top: 0;
}

/* Content pages */
.prose {
    max-width: 720px;
}

.prose h1 {
    font-size: 1.75rem;
    margin-bottom: 12px;
}

.prose h2 {
    font-size: 1.15rem;
    margin: 24px 0 8px;
}

.prose p,
.prose li {
    color: var(--text-secondary);
    margin-bottom: 10px;
}

.prose ul {
    padding-left: 1.25rem;
}

.prose a {
    color: var(--accent-blue);
}

/* Footer */
.site-footer {
    margin-top: 28px;
    padding-top: 16px;
    border-top: 1px solid var(--border-color);
    color: var(--text-secondary);
    font-size: 0.88rem;
    display: flex;
    flex-wrap: wrap;
    gap: 8px 16px;
    align-items: center;
    justify-content: space-between;
}

.footer-nav {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

.footer-nav a {
    color: var(--accent-blue);
    text-decoration: none;
}

.footer-nav a:hover,
.footer-nav a[aria-current="page"] {
    text-decoration: underline;
}