:root {
  color-scheme: light dark;

  /* Light theme palette */
  --bg-page-light: #f8fafc;
  --bg-surface-light: #ffffff;
  --bg-subtle-light: #f1f5f9;
  --text-primary-light: #0f172a;
  --text-secondary-light: #475569;
  --border-light: #cbd5e1;
  --border-subtle-light: #e2e8f0;
  --accent-light: #1d4ed8;
  --accent-hover-light: #1e40af;
  --accent-text-light: #ffffff;
  --badge-bg-light: #eff6ff;
  --badge-text-light: #1e40af;
  --error-light: #b91c1c;
  --error-bg-light: #fef2f2;
  --success-light: #15803d;
  --unavailable-bg-light: #f1f5f9;
  --unavailable-text-light: #64748b;

  /* Dark theme palette */
  --bg-page-dark: #0b1120;
  --bg-surface-dark: #111827;
  --bg-subtle-dark: #1e293b;
  --text-primary-dark: #f8fafc;
  --text-secondary-dark: #94a3b8;
  --border-dark: #334155;
  --border-subtle-dark: #1e293b;
  --accent-dark: #3b82f6;
  --accent-hover-dark: #60a5fa;
  --accent-text-dark: #0b1120;
  --badge-bg-dark: #1e3a8a;
  --badge-text-dark: #bfdbfe;
  --error-dark: #f87171;
  --error-bg-dark: #450a0a;
  --success-dark: #4ade80;
  --unavailable-bg-dark: #0f172a;
  --unavailable-text-dark: #94a3b8;

  /* Active tokens (light default + prefers-color-scheme fallback) */
  --bg-page: var(--bg-page-light);
  --bg-surface: var(--bg-surface-light);
  --bg-subtle: var(--bg-subtle-light);
  --text-primary: var(--text-primary-light);
  --text-secondary: var(--text-secondary-light);
  --border: var(--border-light);
  --border-subtle: var(--border-subtle-light);
  --accent: var(--accent-light);
  --accent-hover: var(--accent-hover-light);
  --accent-text: var(--accent-text-light);
  --badge-bg: var(--badge-bg-light);
  --badge-text: var(--badge-text-light);
  --error: var(--error-light);
  --error-bg: var(--error-bg-light);
  --success: var(--success-light);
  --unavailable-bg: var(--unavailable-bg-light);
  --unavailable-text: var(--unavailable-text-light);

  --font-sans: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.06);
  --shadow-md: 0 4px 12px -2px rgb(0 0 0 / 0.08);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-page: var(--bg-page-dark);
    --bg-surface: var(--bg-surface-dark);
    --bg-subtle: var(--bg-subtle-dark);
    --text-primary: var(--text-primary-dark);
    --text-secondary: var(--text-secondary-dark);
    --border: var(--border-dark);
    --border-subtle: var(--border-subtle-dark);
    --accent: var(--accent-dark);
    --accent-hover: var(--accent-hover-dark);
    --accent-text: var(--accent-text-dark);
    --badge-bg: var(--badge-bg-dark);
    --badge-text: var(--badge-text-dark);
    --error: var(--error-dark);
    --error-bg: var(--error-bg-dark);
    --success: var(--success-dark);
    --unavailable-bg: var(--unavailable-bg-dark);
    --unavailable-text: var(--unavailable-text-dark);
  }
}

@supports (color: light-dark(white, black)) {
  :root {
    --bg-page: light-dark(var(--bg-page-light), var(--bg-page-dark));
    --bg-surface: light-dark(var(--bg-surface-light), var(--bg-surface-dark));
    --bg-subtle: light-dark(var(--bg-subtle-light), var(--bg-subtle-dark));
    --text-primary: light-dark(var(--text-primary-light), var(--text-primary-dark));
    --text-secondary: light-dark(var(--text-secondary-light), var(--text-secondary-dark));
    --border: light-dark(var(--border-light), var(--border-dark));
    --border-subtle: light-dark(var(--border-subtle-light), var(--border-subtle-dark));
    --accent: light-dark(var(--accent-light), var(--accent-dark));
    --accent-hover: light-dark(var(--accent-hover-light), var(--accent-hover-dark));
    --accent-text: light-dark(var(--accent-text-light), var(--accent-text-dark));
    --badge-bg: light-dark(var(--badge-bg-light), var(--badge-bg-dark));
    --badge-text: light-dark(var(--badge-text-light), var(--badge-text-dark));
    --error: light-dark(var(--error-light), var(--error-dark));
    --error-bg: light-dark(var(--error-bg-light), var(--error-bg-dark));
    --success: light-dark(var(--success-light), var(--success-dark));
    --unavailable-bg: light-dark(var(--unavailable-bg-light), var(--unavailable-bg-dark));
    --unavailable-text: light-dark(var(--unavailable-text-light), var(--unavailable-text-dark));
  }
}

:root:has(> head > meta[name="color-scheme"][content="dark"]) {
  color-scheme: dark;
}

:root:has(> head > meta[name="color-scheme"][content="light"]) {
  color-scheme: light;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-block-size: 100dvb;
  display: grid;
  grid-template-rows: auto 1fr auto;
  font-family: var(--font-sans);
  line-height: 1.5;
  color: var(--text-primary);
  background-color: var(--bg-page);
  accent-color: var(--accent);
}

.visually-hidden:where(:not(:focus-within, :active)) {
  position: absolute !important;
  clip-path: inset(50%) !important;
  overflow: hidden !important;
  width: 1px !important;
  height: 1px !important;
  margin: -1px !important;
  padding: 0 !important;
  border: 0 !important;
  white-space: nowrap !important;
}

.skip-link:focus {
  position: fixed;
  inset-block-start: 0.75rem;
  inset-inline-start: 0.75rem;
  z-index: 100;
  padding: 0.75rem 1rem;
  background: var(--accent);
  color: var(--accent-text);
  border-radius: var(--radius-md);
  font-weight: 600;
  text-decoration: none;
}

:where(a:any-link, button, input, textarea, select):focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 2px;
}

.container {
  inline-size: min(100% - 2rem, 64rem);
  margin-inline: auto;
}

/* Header */
.site-header {
  border-block-end: 1px solid var(--border-subtle);
  background-color: var(--bg-surface);
  padding-block: 1.75rem 1.5rem;
}

.header-layout {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1.25rem 2rem;
}

.header-brand-block {
  flex: 1 1 26rem;
  min-inline-size: 0;
}

.primary-nav {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 1rem;
}

.primary-nav ul,
.footer-nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.theme-toggle-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  min-block-size: 40px;
  padding: 0.35rem 0.75rem;
  font: inherit;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-primary);
  background-color: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: 999px;
  cursor: pointer;
  transition: background-color 0.15s ease, border-color 0.15s ease;
}

.theme-toggle-btn:hover {
  border-color: var(--accent);
}

.theme-icon--moon {
  display: none;
}

:root:has(> head > meta[name="color-scheme"][content="dark"]) .theme-icon--sun {
  display: none;
}
:root:has(> head > meta[name="color-scheme"][content="dark"]) .theme-icon--moon {
  display: inline;
}

@media (prefers-color-scheme: dark) {
  :root:not(:has(> head > meta[name="color-scheme"][content="light"])) .theme-icon--sun {
    display: none;
  }
  :root:not(:has(> head > meta[name="color-scheme"][content="light"])) .theme-icon--moon {
    display: inline;
  }
}

.primary-nav a,
.footer-nav a {
  display: inline-flex;
  align-items: center;
  min-block-size: 40px;
  padding: 0.25rem 0.5rem;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 600;
  text-decoration: none;
  transition: color 0.15s ease, background-color 0.15s ease;
}

.primary-nav a:hover,
.footer-nav a:hover {
  color: var(--text-primary);
  background-color: var(--bg-subtle);
}

.brand {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem;
  margin-block-end: 0.5rem;
}

.badge {
  display: inline-flex;
  align-items: center;
  padding: 0.2rem 0.6rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  background-color: var(--badge-bg);
  color: var(--badge-text);
}

h1 {
  margin: 0;
  font-size: clamp(1.5rem, 1.2rem + 1.5vw, 2.125rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.2;
}

.subtitle {
  margin: 0;
  max-inline-size: 65ch;
  color: var(--text-secondary);
  font-size: 0.975rem;
}

/* Main */
main {
  padding-block: 2rem 3rem;
}

.input-panel {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
}

.panel-header {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 0.75rem 1.25rem;
  padding-block-end: 1rem;
  margin-block-end: 1rem;
  border-block-end: 1px solid var(--border-subtle);
}

.panel-header h2 {
  margin: 0;
  font-size: 1.125rem;
  font-weight: 600;
}

.panel-header-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem 1.25rem;
}

.btn-clear {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-block-size: 40px;
  padding: 0.35rem 0.85rem;
  font: inherit;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
  background-color: transparent;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: color 0.15s ease, border-color 0.15s ease, background-color 0.15s ease;
}

.btn-clear:hover {
  color: var(--text-primary);
  background-color: var(--bg-subtle);
  border-color: var(--text-secondary);
}

.mode-toggle-wrap {
  display: inline-flex;
  align-items: center;
  gap: 0.625rem;
}

.mode-label {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-primary);
}

.switch-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.25rem;
  min-block-size: 44px;
  min-inline-size: 52px;
  background: transparent;
  border: none;
  cursor: pointer;
}

.switch-track {
  position: relative;
  display: inline-flex;
  align-items: center;
  inline-size: 46px;
  block-size: 26px;
  padding: 3px;
  border-radius: 999px;
  background-color: var(--border);
  transition: background-color 0.2s ease;
}

.switch-thumb {
  inline-size: 20px;
  block-size: 20px;
  border-radius: 50%;
  background-color: var(--bg-surface);
  box-shadow: var(--shadow-sm);
  transition: transform 0.2s ease;
}

.switch-btn[aria-checked="true"] .switch-track {
  background-color: var(--accent);
}

.switch-btn[aria-checked="true"] .switch-thumb {
  transform: translateX(20px);
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
}

.field label {
  font-weight: 600;
  font-size: 0.95rem;
}

.hint {
  margin: 0;
  color: var(--text-secondary);
  font-size: 0.875rem;
}

.hint code,
.site-footer code {
  font-family: var(--font-mono);
  font-size: 0.825em;
  padding: 0.1rem 0.35rem;
  border-radius: 0.25rem;
  background-color: var(--bg-subtle);
}

.input-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-block-start: 0.375rem;
}

.input-row input,
.batch-fields textarea,
.resolution-field select {
  min-inline-size: 0;
  min-block-size: 48px;
  padding: 0.625rem 0.875rem;
  font: inherit;
  font-size: max(1rem, 1em);
  color: var(--text-primary);
  background-color: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  transition: border-color 0.15s ease, background-color 0.15s ease;
}

.input-row input {
  flex: 1 1 20rem;
}

.batch-fields {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.batch-fields[hidden],
#single-mode-fields[hidden] {
  display: none;
}

.batch-fields textarea {
  inline-size: 100%;
  resize: vertical;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 1.5;
}

.batch-controls-row {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  gap: 0.75rem 1rem;
}

.resolution-field {
  flex: 1 1 16rem;
  min-inline-size: 0;
}

.input-row input:is(:user-invalid, .user-invalid-fallback),
.batch-fields textarea:is(:user-invalid, .user-invalid-fallback) {
  border-color: var(--error);
  background-color: var(--error-bg);
}

.input-row input:is(:user-valid, .user-valid-fallback),
.batch-fields textarea:is(:user-valid, .user-valid-fallback) {
  border-color: var(--success);
}

.error-msg {
  display: none;
  margin-block-start: 0.25rem;
  color: var(--error);
  font-size: 0.875rem;
  font-weight: 500;
}

.field:has(:is(input, textarea):is(:user-invalid, .user-invalid-fallback)) .error-msg,
.error-msg.is-visible {
  display: block;
}

.btn-primary,
.btn-secondary,
.btn-download {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  min-block-size: 48px;
  padding: 0.625rem 1.25rem;
  font: inherit;
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: background-color 0.15s ease, border-color 0.15s ease, transform 0.1s ease;
}

.btn-primary {
  flex: 0 0 auto;
  background-color: var(--accent);
  color: var(--accent-text);
}

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

.btn-primary:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

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

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

.btn-secondary:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

.btn-primary:active:not(:disabled),
.btn-secondary:active:not(:disabled),
.btn-download:active:not(:disabled) {
  transform: translateY(1px);
}

/* Results */
.results-section {
  margin-block-start: 2rem;
}

.results-header {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: baseline;
  gap: 0.75rem;
  margin-block-end: 1.25rem;
}

.results-header h2 {
  margin: 0;
  font-size: 1.25rem;
  font-weight: 600;
}

.video-meta {
  margin: 0.25rem 0 0;
  color: var(--text-secondary);
  font-size: 0.875rem;
}

.video-id-chip {
  font-family: var(--font-mono);
  font-weight: 600;
  color: var(--text-primary);
  background-color: var(--bg-subtle);
  padding: 0.15rem 0.45rem;
  border-radius: 0.25rem;
}

.thumbnail-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 280px), 1fr));
  gap: 1.25rem;
}

.thumbnail-card {
  display: grid;
  grid-template-rows: auto 1fr auto;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.thumbnail-frame {
  position: relative;
  aspect-ratio: 16 / 9;
  background-color: var(--bg-subtle);
  border-block-end: 1px solid var(--border-subtle);
  display: grid;
  place-items: center;
}

.thumbnail-frame img {
  display: block;
  inline-size: 100%;
  block-size: 100%;
  object-fit: cover;
}

.thumbnail-frame img[hidden] {
  display: none;
}

.unavailable-placeholder {
  display: grid;
  place-items: center;
  gap: 0.35rem;
  padding: 1.25rem;
  text-align: center;
  inline-size: 100%;
  block-size: 100%;
  background-color: var(--unavailable-bg);
  color: var(--unavailable-text);
}

.unavailable-placeholder[hidden] {
  display: none;
}

.unavailable-badge {
  display: inline-block;
  padding: 0.25rem 0.65rem;
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 600;
  border: 1px solid var(--border);
  background-color: var(--bg-surface);
}

.unavailable-note {
  margin: 0;
  font-size: 0.8rem;
}

.card-body {
  padding: 1rem 1.125rem 0.75rem;
  min-inline-size: 0;
}

.card-title-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 0.5rem;
}

.card-title {
  margin: 0;
  font-size: 1rem;
  font-weight: 600;
}

.card-dimensions {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.card-filename {
  margin: 0.35rem 0 0;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-secondary);
  overflow-wrap: anywhere;
}

.card-actions {
  padding: 0 1.125rem 1.125rem;
}

.btn-download {
  inline-size: 100%;
  background-color: var(--bg-subtle);
  color: var(--text-primary);
  border-color: var(--border);
}

.btn-download:hover:not(:disabled) {
  background-color: var(--accent);
  color: var(--accent-text);
  border-color: var(--accent);
}

.btn-download:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

/* Batch Results Table */
.batch-export-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.625rem;
}

.zip-progress-panel {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1rem 1.125rem;
  margin-block-end: 1rem;
  box-shadow: var(--shadow-sm);
}

.zip-progress-panel[hidden],
.zip-summary-alert[hidden] {
  display: none;
}

.zip-progress-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 0.75rem;
  margin-block-end: 0.5rem;
  font-size: 0.9rem;
  font-weight: 600;
}

.zip-progress-percent {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--text-secondary);
}

#zip-progress-bar {
  display: block;
  inline-size: 100%;
  block-size: 0.625rem;
  accent-color: var(--accent);
}

.zip-summary-alert {
  padding: 0.875rem 1.125rem;
  margin-block-end: 1rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  background-color: var(--bg-surface);
  font-size: 0.9rem;
  font-weight: 500;
}

.zip-summary-alert--success {
  border-color: var(--success);
  background-color: var(--badge-bg);
  color: var(--text-primary);
}

.zip-summary-alert--warning {
  border-color: var(--error);
  background-color: var(--error-bg);
  color: var(--error);
}

.table-wrapper {
  overflow: auto;
  max-inline-size: 100%;
  max-block-size: min(620px, 75dvb);
  container-type: inline-size;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}

.batch-table {
  inline-size: 100%;
  border-collapse: separate;
  border-spacing: 0;
  text-align: start;
  font-size: 0.9rem;
  --label-1: "Thumbnail Preview";
  --label-2: "Video ID";
  --label-3: "Detected Resolution";
  --label-4: "Direct Image URL";
}

.batch-table thead {
  position: sticky;
  inset-block-start: 0;
  z-index: 2;
}

.batch-table th {
  background-color: var(--bg-subtle);
  color: var(--text-primary);
  font-weight: 600;
  padding: 0.875rem 1rem;
  border-block-end: 1px solid var(--border);
  white-space: nowrap;
}

.batch-table td,
.batch-table tbody th {
  padding: 0.75rem 1rem;
  border-block-end: 1px solid var(--border-subtle);
  vertical-align: middle;
}

.batch-table tbody th {
  background-color: var(--bg-surface);
  font-family: var(--font-mono);
  font-weight: 600;
  white-space: nowrap;
}

.batch-table tbody tr:last-child td,
.batch-table tbody tr:last-child th {
  border-block-end: none;
}

.table-preview-frame {
  inline-size: 128px;
  aspect-ratio: 16 / 9;
  border-radius: 0.375rem;
  overflow: hidden;
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-subtle);
  display: grid;
  place-items: center;
}

.table-preview-frame img {
  display: block;
  inline-size: 100%;
  block-size: 100%;
  object-fit: cover;
}

.table-unavailable {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--unavailable-text);
}

.res-pill {
  display: inline-flex;
  align-items: center;
  padding: 0.2rem 0.55rem;
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 600;
  background-color: var(--badge-bg);
  color: var(--badge-text);
  white-space: nowrap;
}

.res-pill--unavailable {
  background-color: var(--unavailable-bg);
  color: var(--unavailable-text);
  border: 1px solid var(--border);
}

.direct-url-link {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent);
  overflow-wrap: anywhere;
  text-decoration: none;
}

.direct-url-link:hover {
  text-decoration: underline;
}

@container (width < 640px) {
  .batch-table,
  .batch-table thead,
  .batch-table tbody,
  .batch-table tr,
  .batch-table th,
  .batch-table td {
    display: block;
  }

  .batch-table thead {
    display: none;
  }

  .batch-table tbody tr {
    margin-block-end: 1rem;
    border-block-end: 2px solid var(--border);
    padding-block-end: 0.5rem;
  }

  .batch-table tbody th {
    position: sticky;
    inset-block-start: 0;
    z-index: 1;
    background-color: var(--bg-subtle);
    border-block-end: 1px solid var(--border);
  }

  .batch-table td::before {
    display: block;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-block-end: 0.25rem;
  }

  .batch-table td:nth-child(1)::before {
    content: var(--label-1);
  }

  .batch-table td:nth-child(3)::before {
    content: var(--label-3);
  }

  .batch-table td:nth-child(4)::before {
    content: var(--label-4);
  }
}

/* Content Sections (Tutorial, Resolutions, FAQ) */
.content-section {
  margin-block-start: 3rem;
  padding-block-start: 2rem;
  border-block-start: 1px solid var(--border-subtle);
}

.content-section h2 {
  margin: 0 0 0.5rem;
  font-size: clamp(1.25rem, 1.1rem + 0.6vw, 1.5rem);
  font-weight: 700;
  letter-spacing: -0.015em;
}

.section-lead {
  margin: 0 0 1.5rem;
  max-inline-size: 68ch;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.section-lead code,
.info-card code,
.reference-table code,
.research-callout code,
.faq-item code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  padding: 0.1rem 0.35rem;
  border-radius: 0.25rem;
  background-color: var(--bg-subtle);
}

.step-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 250px), 1fr));
  gap: 1.25rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.info-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  box-shadow: var(--shadow-sm);
}

.info-card h3 {
  margin: 0 0 0.5rem;
  font-size: 1rem;
  font-weight: 600;
}

.info-card p {
  margin: 0;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.reference-table {
  inline-size: 100%;
  border-collapse: separate;
  border-spacing: 0;
  text-align: start;
  font-size: 0.9rem;
  --label-1: "Quality Tier";
  --label-2: "Filename";
  --label-3: "Dimensions";
  --label-4: "Research Notes";
}

.reference-table th {
  background-color: var(--bg-subtle);
  color: var(--text-primary);
  font-weight: 600;
  padding: 0.875rem 1rem;
  border-block-end: 1px solid var(--border);
  white-space: nowrap;
}

.reference-table td,
.reference-table tbody th {
  padding: 0.75rem 1rem;
  border-block-end: 1px solid var(--border-subtle);
  vertical-align: top;
}

.reference-table tbody th {
  background-color: var(--bg-surface);
  font-weight: 600;
  white-space: nowrap;
}

.reference-table tbody tr:last-child td,
.reference-table tbody tr:last-child th {
  border-block-end: none;
}

@container (width < 640px) {
  .reference-table,
  .reference-table thead,
  .reference-table tbody,
  .reference-table tr,
  .reference-table th,
  .reference-table td {
    display: block;
  }

  .reference-table thead {
    display: none;
  }

  .reference-table tbody tr {
    margin-block-end: 1rem;
    border-block-end: 2px solid var(--border);
    padding-block-end: 0.5rem;
  }

  .reference-table tbody th {
    background-color: var(--bg-subtle);
    border-block-end: 1px solid var(--border);
  }

  .reference-table td::before {
    display: block;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-block-end: 0.25rem;
  }

  .reference-table td:nth-child(2)::before {
    content: var(--label-2);
  }

  .reference-table td:nth-child(3)::before {
    content: var(--label-3);
  }

  .reference-table td:nth-child(4)::before {
    content: var(--label-4);
  }
}

.research-callout {
  margin-block-start: 1.5rem;
  padding: 1.25rem 1.5rem;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-inline-start: 4px solid var(--accent);
  border-radius: var(--radius-md);
}

.research-callout h3 {
  margin: 0 0 0.4rem;
  font-size: 1rem;
  font-weight: 600;
}

.research-callout p {
  margin: 0;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.faq-list {
  display: grid;
  gap: 0.75rem;
}

.faq-item {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 0.25rem 1.125rem;
}

.faq-item summary {
  padding-block: 0.875rem;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  list-style-position: outside;
}

.faq-item p {
  margin: 0 0 1rem;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

/* Footer */
.site-footer {
  border-block-start: 1px solid var(--border-subtle);
  background-color: var(--bg-surface);
  padding-block: 1.75rem;
  color: var(--text-secondary);
  font-size: 0.875rem;
}

.footer-layout {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 1rem 2rem;
}

.footer-about {
  flex: 1 1 24rem;
  min-inline-size: 0;
}

.footer-title {
  font-weight: 600;
  color: var(--text-primary);
  margin-block-end: 0.25rem;
}

.site-footer p {
  margin: 0;
}

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

.footer-about a:hover {
  text-decoration: underline;
}

@media (pointer: coarse) {
  .input-row input,
  .btn-primary,
  .btn-download {
    min-block-size: 52px;
  }
}