/* ================================
   ROOT VARIABLES
   ================================ */
:root {
  --clr-bg: #ffffff;
  --clr-bg-alt: #f7f7f9;
  --clr-surface: #ffffff;
  --clr-border: #e1e1e6;
  --clr-text: #1a1a2e;
  --clr-text-muted: #5b6370;
  --clr-accent: #2563eb;
  --clr-accent-hover: #1d4ed8;
  --clr-success: #16a34a;
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'Fira Code', 'Courier New', Courier, monospace;
  --radius: 0.5rem;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.12);
}

[data-theme="dark"] {
  --clr-bg: #0f172a;
  --clr-bg-alt: #1e293b;
  --clr-surface: #1e293b;
  --clr-border: #334155;
  --clr-text: #f1f5f9;
  --clr-text-muted: #94a3b8;
  --clr-accent: #3b82f6;
  --clr-accent-hover: #60a5fa;
  --clr-success: #22c55e;
}

/* ================================
   RESET
   ================================ */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

[hidden] {
  display: none !important;
}

html {
  font-size: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background-color: var(--clr-bg);
  color: var(--clr-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

img,
video {
  max-width: 100%;
  display: block;
}

/* ================================
   SKIP LINK
   ================================ */
.skip-link {
  position: absolute;
  top: -100%;
  left: 1rem;
  z-index: 9999;
  background-color: var(--clr-accent);
  color: #ffffff;
  padding: 0.5rem 1rem;
  border-radius: var(--radius);
  font-weight: 600;
  text-decoration: none;
}

.skip-link:focus {
  top: 1rem;
  color: #ffffff;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
}

/* ================================
   TYPOGRAPHY
   ================================ */
h1,
h2,
h3,
h4,
h5,
h6 {
  line-height: 1.25;
  font-weight: 700;
}

h1 { font-size: clamp(1.75rem, 1.4rem + 1.75vw, 2.75rem); }
h2 { font-size: clamp(1.375rem, 1.1rem + 1.375vw, 2rem); }
h3 { font-size: clamp(1.125rem, 1rem + 0.625vw, 1.5rem); }

p {
  margin-bottom: 1rem;
}

p:last-child {
  margin-bottom: 0;
}

a {
  color: var(--clr-accent);
  text-decoration: underline;
}

a:hover {
  color: var(--clr-accent-hover);
}

code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background-color: var(--clr-bg-alt);
  border: 1px solid var(--clr-border);
  border-radius: 0.25rem;
  padding: 0.125em 0.375em;
}

/* ================================
   LAYOUT
   ================================ */
.site-main {
  width: 100%;
  max-width: 72rem;
  margin-inline: auto;
  padding-inline: 1.25rem;
}

.content-layout {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: 2rem;
  align-items: start;
  margin-block: 2rem;
}

@media (max-width: 64em) {
  .content-layout {
    grid-template-columns: 1fr;
  }
}

/* ================================
   SITE HEADER
   ================================ */
.site-header {
  border-bottom: 1px solid var(--clr-border);
  padding-block: 1rem;
  background-color: var(--clr-surface);
  position: sticky;
  top: 0;
  z-index: 100;
}

.site-header__inner {
  max-width: 72rem;
  margin-inline: auto;
  padding-inline: 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-header__logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.25rem;
  font-weight: 700;
  text-decoration: none;
  color: var(--clr-text);
}

.site-header__icon {
  width: 2rem;
  height: 2rem;
  flex-shrink: 0;
}

.site-header__logo:hover {
  color: var(--clr-accent);
}

.site-header__actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.site-header__hub-link {
  display: inline-flex;
  align-items: center;
  height: 2.25rem;
  padding-inline: 0.75rem;
  border: 1px solid var(--clr-border);
  border-radius: 999px;
  color: var(--clr-text-muted);
  text-decoration: none;
  font-size: 0.8125rem;
  font-weight: 600;
  white-space: nowrap;
  transition: border-color 0.15s ease, color 0.15s ease, background-color 0.15s ease;
}

.site-header__hub-link:hover {
  border-color: var(--clr-accent);
  color: var(--clr-accent);
  background-color: var(--clr-bg-alt);
}

.site-header__hub-link:focus-visible {
  outline: 3px solid rgba(37, 99, 235, 0.4);
  outline-offset: 2px;
}

[data-theme="dark"] .site-header__hub-link:focus-visible {
  outline-color: rgba(96, 165, 250, 0.4);
}

/* ================================
   THEME TOGGLE
   ================================ */
.theme-toggle {
  background: none;
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  padding: 0.375rem 0.625rem;
  cursor: pointer;
  font-size: 1rem;
  color: var(--clr-text);
  transition: background-color 0.15s ease, border-color 0.15s ease;
}

.theme-toggle:hover {
  background-color: var(--clr-bg-alt);
  color: var(--clr-text);
}

.theme-toggle:focus-visible {
  outline: 3px solid var(--clr-accent);
  outline-offset: 2px;
}

.theme-toggle__icon--dark {
  display: none;
}

[data-theme="dark"] .theme-toggle__icon--light {
  display: none;
}

[data-theme="dark"] .theme-toggle__icon--dark {
  display: inline;
}

/* ================================
   TOOL SECTION
   ================================ */
.tool-section {
  background-color: var(--clr-bg-alt);
  border-bottom: 1px solid var(--clr-border);
  padding-block: 2.5rem;
}

.tool-section__inner {
  max-width: 72rem;
  margin-inline: auto;
  padding-inline: 1.25rem;
}

.tool-section__title {
  margin-bottom: 0.5rem;
}

.tool-section__description {
  color: var(--clr-text-muted);
  margin-bottom: 1.75rem;
  max-width: 60ch;
}

/* ================================
   TAB NAVIGATION
   ================================ */
.tab-nav {
  display: flex;
  gap: 0.25rem;
  border-bottom: 2px solid var(--clr-border);
  margin-bottom: 1.75rem;
}

.tab-btn {
  padding: 0.625rem 1.25rem;
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--clr-text-muted);
  cursor: pointer;
  transition: color 0.15s ease, border-color 0.15s ease;
  border-radius: var(--radius) var(--radius) 0 0;
}

.tab-btn:hover {
  color: var(--clr-text);
}

.tab-btn--active {
  color: var(--clr-accent);
  border-bottom-color: var(--clr-accent);
}

.tab-btn:focus-visible {
  outline: 3px solid var(--clr-accent);
  outline-offset: 2px;
}

/* ================================
   TOOL LAYOUT (CONTROLS + PREVIEW)
   ================================ */
.tool-layout {
  display: grid;
  grid-template-columns: 340px 1fr;
  gap: 1.75rem;
  align-items: start;
}

@media (max-width: 56em) {
  .tool-layout {
    grid-template-columns: 1fr;
  }
}

/* ================================
   TOOL CONTROLS
   ================================ */
.tool-controls {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.control-intro {
  font-size: 0.9rem;
  color: var(--clr-text-muted);
  margin-bottom: 0;
  line-height: 1.55;
}

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

.control-group__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.control-group__label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--clr-text);
}

.control-fieldset {
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.875rem;
}

.control-fieldset__legend {
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.075em;
  color: var(--clr-text-muted);
  padding-inline: 0.375rem;
}

.grid-2col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.875rem;
}

/* ================================
   FORM ELEMENTS
   ================================ */
.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
}

.form-group__label {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--clr-text);
}

.form-group__input {
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: 0.875rem;
  background-color: var(--clr-surface);
  color: var(--clr-text);
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
  width: 100%;
}

.form-group__input:focus {
  outline: none;
  border-color: var(--clr-accent);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}

select.form-group__input {
  font-family: var(--font-sans);
  cursor: pointer;
}

.form-group__hint {
  font-size: 0.8rem;
  color: var(--clr-text-muted);
  line-height: 1.5;
}

/* ================================
   TRACK HINTS (CHIP BUTTONS)
   ================================ */
.track-hints {
  display: flex;
  gap: 0.25rem;
  flex-wrap: wrap;
}

.track-hint-btn {
  padding: 0.2rem 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  background-color: var(--clr-bg);
  border: 1px solid var(--clr-border);
  border-radius: 0.25rem;
  color: var(--clr-accent);
  cursor: pointer;
  transition: background-color 0.1s ease, border-color 0.1s ease;
  white-space: nowrap;
}

.track-hint-btn:hover {
  background-color: var(--clr-accent);
  border-color: var(--clr-accent);
  color: #ffffff;
}

.track-hint-btn:focus-visible {
  outline: 2px solid var(--clr-accent);
  outline-offset: 1px;
}

/* ================================
   GAP ROW
   ================================ */
.gap-row {
  display: flex;
  align-items: flex-end;
  gap: 0.75rem;
}

.gap-input-group {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  flex: 1;
}

.gap-input-group__label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--clr-text-muted);
}

.gap-input-group__input {
  max-width: 100%;
}

.link-toggle {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.25rem;
  cursor: pointer;
  padding-bottom: 0.1rem;
  flex-shrink: 0;
}

.link-toggle input[type="checkbox"] {
  width: 1rem;
  height: 1rem;
  cursor: pointer;
  accent-color: var(--clr-accent);
}

.link-toggle__label {
  font-size: 0.7rem;
  color: var(--clr-text-muted);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ================================
   TOGGLE LABEL
   ================================ */
.toggle-label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  cursor: pointer;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--clr-text);
}

.toggle-label__checkbox {
  width: 1rem;
  height: 1rem;
  cursor: pointer;
  accent-color: var(--clr-accent);
}

/* ================================
   NAMED AREAS GRID
   ================================ */
.areas-grid {
  display: grid;
  gap: 4px;
}

.areas-cell {
  padding: 0.375rem 0.5rem;
  border: 1px solid var(--clr-border);
  border-radius: 0.25rem;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  background-color: var(--clr-surface);
  color: var(--clr-text);
  text-align: center;
  width: 100%;
  min-width: 0;
  transition: border-color 0.1s ease;
}

.areas-cell:focus {
  outline: none;
  border-color: var(--clr-accent);
  box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.2);
}

.areas-error {
  margin-top: 0.5rem;
  padding: 0.5rem 0.75rem;
  background-color: #fef2f2;
  border: 1px solid #fca5a5;
  border-radius: var(--radius);
  font-size: 0.8125rem;
  color: #dc2626;
}

[data-theme="dark"] .areas-error {
  background-color: #450a0a;
  border-color: #7f1d1d;
  color: #fca5a5;
}

/* ================================
   ADD ITEM BUTTON
   ================================ */
.add-item-btn {
  padding: 0.3rem 0.75rem;
  background-color: var(--clr-accent);
  color: #ffffff;
  border: none;
  border-radius: var(--radius);
  font-size: 0.8125rem;
  font-weight: 600;
  cursor: pointer;
  transition: background-color 0.15s ease;
  white-space: nowrap;
  flex-shrink: 0;
}

.add-item-btn:hover {
  background-color: var(--clr-accent-hover);
  color: #ffffff;
}

.add-item-btn:focus-visible {
  outline: 3px solid var(--clr-accent);
  outline-offset: 2px;
}

/* ================================
   FLEX ITEMS LIST
   ================================ */
.flex-items-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.flex-item-card {
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  background-color: var(--clr-surface);
}

.flex-item-card__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.5rem 0.75rem;
  background-color: var(--clr-bg-alt);
  border-bottom: 1px solid var(--clr-border);
  border-radius: var(--radius) var(--radius) 0 0;
}

.flex-item-card__label {
  font-size: 0.8125rem;
  font-weight: 700;
  color: var(--clr-text-muted);
}

.flex-item-card__remove {
  background: none;
  border: 1px solid var(--clr-border);
  border-radius: 0.25rem;
  width: 1.5rem;
  height: 1.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  line-height: 1;
  color: var(--clr-text-muted);
  cursor: pointer;
  transition: background-color 0.1s ease, color 0.1s ease;
}

.flex-item-card__remove:hover {
  background-color: #fef2f2;
  border-color: #fca5a5;
  color: #dc2626;
}

.flex-item-card__remove:focus-visible {
  outline: 2px solid var(--clr-accent);
  outline-offset: 1px;
}

.flex-item-card__body {
  padding: 0.75rem;
}

.flex-item-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.625rem;
}

/* ================================
   TOOL PREVIEW (RIGHT COLUMN)
   ================================ */
.tool-preview {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  min-width: 0;
}

/* ================================
   PREVIEW PANE
   ================================ */
.preview-pane {
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--clr-surface);
}

.preview-pane__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.625rem 0.875rem;
  background-color: var(--clr-bg-alt);
  border-bottom: 1px solid var(--clr-border);
}

.preview-pane__label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.075em;
  color: var(--clr-text-muted);
}

.preview-pane__meta {
  font-size: 0.75rem;
  color: var(--clr-text-muted);
  font-family: var(--font-mono);
}

.preview-container {
  padding: 1rem;
  min-height: 220px;
}

.preview-container--flex {
  min-height: 140px;
}

.preview-container--subgrid {
  min-height: 200px;
  overflow: auto;
}

/* Preview grid/flex items */
.preview-item {
  padding: 0.5rem 0.625rem;
  border-radius: 0.375rem;
  border: 1px solid transparent;
  font-size: 0.75rem;
  font-weight: 600;
  font-family: var(--font-mono);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 2.5rem;
  word-break: break-word;
  text-align: center;
}

.preview-item--parent {
  border: 2px dashed var(--clr-border);
  background: transparent;
  position: relative;
  min-height: 140px;
}

.preview-item--child-subgrid {
  position: absolute;
  border: 2px solid rgba(37, 99, 235, 0.6);
  background: rgba(37, 99, 235, 0.08);
  color: var(--clr-accent);
}

/* ================================
   SUBGRID INTERACTIVE PREVIEW
   ================================ */
.preview-item--bg {
  cursor: pointer;
  position: relative;
  transition: background-color 0.15s;
}

.preview-item--bg:hover {
  background-color: rgba(59, 130, 246, 0.1) !important;
  color: transparent !important;
}

.preview-item--bg::after {
  content: "+";
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  font-weight: 700;
  color: var(--clr-accent);
  opacity: 0;
  transition: opacity 0.15s;
  pointer-events: none;
}

.preview-item--bg:hover::after {
  opacity: 0.6;
}

.preview-item--subchild {
  position: relative;
  cursor: default;
}

.subgrid-handle {
  position: absolute;
  z-index: 10;
  opacity: 0;
  background: var(--clr-accent);
  border-radius: 2px;
  transition: opacity 0.15s;
}

.preview-item--subchild:hover .subgrid-handle {
  opacity: 0.4;
}

.subgrid-handle:hover {
  opacity: 1 !important;
}

.subgrid-handle--left {
  left: -3px;
  top: 4px;
  bottom: 4px;
  width: 6px;
  cursor: col-resize;
}

.subgrid-handle--right {
  right: -3px;
  top: 4px;
  bottom: 4px;
  width: 6px;
  cursor: col-resize;
}

.subgrid-handle--top {
  top: -3px;
  left: 4px;
  right: 4px;
  height: 6px;
  cursor: row-resize;
}

.subgrid-handle--bottom {
  bottom: -3px;
  left: 4px;
  right: 4px;
  height: 6px;
  cursor: row-resize;
}

/* ================================
   GRID LINE LABELS
   ================================ */
.grid-line-label {
  font-size: 0.5rem;
  font-family: var(--font-mono);
  color: var(--clr-accent);
  background-color: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: 3px;
  pointer-events: none;
  user-select: none;
  line-height: 1;
  padding: 1px 3px;
  z-index: 5;
}

.grid-line-label--col {
  justify-self: start;
  align-self: start;
}

.grid-line-label--row {
  justify-self: start;
  align-self: start;
}

/* ================================
   GRID ITEM REMOVE BUTTON
   ================================ */
.grid-item-remove {
  position: absolute;
  top: 2px;
  right: 2px;
  width: 18px;
  height: 18px;
  padding: 0;
  border: none;
  border-radius: 50%;
  background: rgba(0, 0, 0, 0.25);
  color: #fff;
  font-size: 0.75rem;
  line-height: 1;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.15s;
  display: flex;
  align-items: center;
  justify-content: center;
}

.preview-item--subchild:hover .grid-item-remove {
  opacity: 1;
}

.grid-item-remove:hover {
  background: rgba(220, 38, 38, 0.8);
}

/* ================================
   OUTPUT PANE
   ================================ */
.output-pane {
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  overflow: hidden;
}

.output-pane__header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
  padding: 0.625rem 0.875rem;
  background-color: var(--clr-bg-alt);
  border-bottom: 1px solid var(--clr-border);
}

.output-pane__label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  flex: 1 1 auto;
  letter-spacing: 0.075em;
  color: var(--clr-text-muted);
}

.output-toggle {
  display: flex;
  gap: 0;
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  overflow: hidden;
  flex: 0 0 auto;
}

.output-toggle__btn {
  padding: 0.25rem 0.625rem;
  font-size: 0.6875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  border: none;
  background: transparent;
  color: var(--clr-text-muted);
  cursor: pointer;
  transition: background-color 0.15s, color 0.15s;
}

.output-toggle__btn--active {
  background-color: var(--clr-accent);
  color: #ffffff;
}

.output-toggle__btn:hover:not(.output-toggle__btn--active) {
  background-color: var(--clr-bg);
  color: var(--clr-text);
}

.copy-btn {
  padding: 0.3rem 0.875rem;
  background-color: var(--clr-accent);
  color: #ffffff;
  border: none;
  border-radius: var(--radius);
  font-size: 0.8125rem;
  font-weight: 600;
  cursor: pointer;
  transition: background-color 0.15s ease;
  white-space: nowrap;
}

.copy-btn:hover {
  background-color: var(--clr-accent-hover);
  color: #ffffff;
}

.copy-btn:focus-visible {
  outline: 3px solid var(--clr-accent);
  outline-offset: 2px;
}

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

.output-code {
  display: block;
  padding: 1rem;
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  line-height: 1.65;
  color: var(--clr-text);
  background-color: var(--clr-bg);
  white-space: pre;
  overflow-x: auto;
  min-height: 5rem;
  tab-size: 2;
}

.output-code:focus-visible {
  outline: 3px solid var(--clr-accent);
  outline-offset: -3px;
}

/* ================================
   CONTENT SECTION
   ================================ */
.content-section {
  padding-block: 2rem 0;
}

.content-section__body h2 {
  margin-bottom: 0.75rem;
  margin-top: 2rem;
}

.content-section__body h2:first-child {
  margin-top: 0;
}

.content-section__body h3 {
  margin-bottom: 0.5rem;
  margin-top: 1.5rem;
}

.content-section__body p {
  color: var(--clr-text);
  max-width: 70ch;
}

.content-section__body ul,
.content-section__body ol {
  padding-left: 1.5rem;
  margin-bottom: 1rem;
}

.content-section__body li {
  margin-bottom: 0.375rem;
}

/* ================================
   FAQ SECTION
   ================================ */
.faq-section {
  padding-block: 2.5rem;
  border-top: 1px solid var(--clr-border);
}

.faq-section__inner {
  max-width: 72rem;
  margin-inline: auto;
  padding-inline: 1.25rem;
}

.faq-section__title {
  margin-bottom: 1.5rem;
}

.faq__item {
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  margin-bottom: 0.625rem;
  overflow: hidden;
}

.faq__question {
  padding: 1rem 1.25rem;
  font-weight: 600;
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  background-color: var(--clr-surface);
  transition: background-color 0.15s ease;
}

.faq__question:hover {
  background-color: var(--clr-bg-alt);
}

.faq__question:focus-visible {
  outline: 3px solid var(--clr-accent);
  outline-offset: -3px;
}

.faq__question::-webkit-details-marker {
  display: none;
}

.faq__question::after {
  content: '+';
  font-size: 1.25rem;
  font-weight: 400;
  flex-shrink: 0;
  margin-left: 1rem;
}

details[open] .faq__question::after {
  content: '-';
}

.faq__answer {
  padding: 0 1.25rem 1rem;
  color: var(--clr-text);
  background-color: var(--clr-surface);
}

/* ================================
   CONTENT SIDEBAR
   ================================ */
.content-sidebar {
  position: sticky;
  top: 5rem;
}

/* ================================
   SITE FOOTER
   ================================ */
.site-footer {
  background-color: var(--clr-bg-alt);
  border-top: 1px solid var(--clr-border);
  padding-block: 1.5rem;
  margin-top: 3rem;
}

.site-footer__inner {
  max-width: 72rem;
  margin-inline: auto;
  padding-inline: 1.25rem;
}

.site-footer__copy {
  font-size: 0.875rem;
  color: var(--clr-text-muted);
  text-align: center;
}

.site-footer__hub-link-wrap {
  margin-top: 0.375rem;
  font-size: 0.8125rem;
  color: var(--clr-text-muted);
  text-align: center;
}

.site-footer__hub-link {
  font-weight: 600;
}

/* ================================
   RESPONSIVE — TABLET (max 48em)
   ================================ */
@media (max-width: 48em) {
  .site-main {
    padding-inline: 0;
  }

  .content-layout {
    padding-inline: 1rem;
  }

  .tool-section {
    padding-block: 1.75rem;
  }

  .tool-section__inner {
    padding-inline: 1rem;
  }

  .ad-slot--inline {
    display: none;
  }

  .ad-slot--leaderboard,
  .ad-slot--rectangle {
    margin-inline: 1rem;
  }

  .grid-2col {
    grid-template-columns: 1fr 1fr;
  }

  .flex-item-row {
    grid-template-columns: 1fr 1fr;
  }
}

/* ================================
   RESPONSIVE — MOBILE (max 36em)
   ================================ */
@media (max-width: 36em) {
  .tool-section__inner,
  .faq-section__inner {
    padding-inline: 0.75rem;
  }

  .site-header__inner,
  .site-footer__inner {
    padding-inline: 0.75rem;
  }

  .content-layout {
    padding-inline: 0.75rem;
  }

  [data-tooltip]::after {
    left: 0;
    transform: none;
    max-width: 180px;
  }

  [data-tooltip]::before {
    left: 1rem;
    transform: none;
  }

  .ad-slot--leaderboard,
  .ad-slot--rectangle {
    margin-inline: 0.75rem;
  }

  .faq-section__inner {
    padding-inline: 0.75rem;
  }

  .faq__question {
    padding: 0.75rem 1rem;
    font-size: 0.9375rem;
  }

  .faq__answer {
    padding: 0 1rem 0.75rem;
    font-size: 0.9375rem;
  }

  .tab-btn {
    padding: 0.5rem 0.75rem;
    font-size: 0.875rem;
  }

  .grid-2col {
    grid-template-columns: 1fr;
  }

  .flex-item-row {
    grid-template-columns: 1fr;
  }
}

/* ================================
   REDUCED MOTION
   ================================ */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* ================================
   TOOLTIPS
   ================================ */
[data-tooltip] {
  position: relative;
}

[data-tooltip]::after {
  content: attr(data-tooltip);
  position: absolute;
  bottom: calc(100% + 7px);
  left: 50%;
  transform: translateX(-50%);
  background-color: #1a2332;
  color: #f1f5f9;
  font-size: 0.6875rem;
  font-family: var(--font-sans);
  font-weight: 400;
  line-height: 1.45;
  padding: 0.375rem 0.625rem;
  border-radius: 0.375rem;
  white-space: normal;
  width: max-content;
  max-width: 220px;
  pointer-events: none;
  opacity: 0;
  z-index: 300;
  text-align: left;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.35);
  transition: opacity 0.15s ease;
}

[data-tooltip]::before {
  content: "";
  position: absolute;
  bottom: calc(100% + 1px);
  left: 50%;
  transform: translateX(-50%);
  border: 5px solid transparent;
  border-top-color: #1a2332;
  pointer-events: none;
  opacity: 0;
  z-index: 300;
  transition: opacity 0.15s ease;
}

[data-tooltip]:hover::after,
[data-tooltip]:focus::after,
[data-tooltip]:focus-visible::after {
  opacity: 1;
}

[data-tooltip]:hover::before,
[data-tooltip]:focus::before,
[data-tooltip]:focus-visible::before {
  opacity: 1;
}

[data-theme="light"] [data-tooltip]::after {
  background-color: #1e293b;
}

[data-theme="light"] [data-tooltip]::before {
  border-top-color: #1e293b;
}

/* ================================
   INFO BUTTON
   ================================ */
.info-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0 0.1875rem;
  font-size: 0.8125rem;
  line-height: 1;
  color: var(--clr-text-muted);
  vertical-align: middle;
  position: relative;
  border-radius: 50%;
  transition: color 0.15s ease;
}

.info-btn:hover,
.info-btn:focus-visible {
  color: var(--clr-accent);
  outline: none;
}

.info-btn:focus-visible {
  outline: 2px solid var(--clr-accent);
  outline-offset: 1px;
}

/* ================================
   SELECTOR GROUP
   ================================ */
.selector-group {
  display: inline-flex;
  align-items: stretch;
  border: 1px solid var(--clr-border);
  border-radius: 0.375rem;
  overflow: hidden;
  cursor: text;
  font-size: 0.8125rem;
}

.selector-group__prefix {
  display: flex;
  align-items: center;
  padding: 0.2rem 0.3rem 0.2rem 0.5rem;
  background: var(--clr-bg-alt);
  color: var(--clr-accent);
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.875rem;
  border-right: 1px solid var(--clr-border);
  user-select: none;
}

.selector-group__input {
  border: none;
  background: var(--clr-surface);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--clr-text);
  padding: 0.2rem 0.5rem;
  width: 7rem;
  min-width: 0;
}

.selector-group__input:focus {
  outline: none;
  background: var(--clr-bg);
}

.selector-group__input:focus-visible {
  outline: 2px solid var(--clr-accent);
  outline-offset: -2px;
  background: var(--clr-bg);
}

/* ================================
   RESET BUTTON
   ================================ */
.reset-btn {
  padding: 0.3rem 0.75rem;
  background: none;
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--clr-text-muted);
  cursor: pointer;
  transition:
    background-color 0.15s ease,
    color 0.15s ease,
    border-color 0.15s ease;
  position: relative;
}

.reset-btn:hover {
  background-color: var(--clr-bg-alt);
  border-color: var(--clr-text-muted);
  color: var(--clr-text);
}

.reset-btn:focus-visible {
  outline: 2px solid var(--clr-accent);
  outline-offset: 2px;
}

/* ================================
   CONTROLS HEADER
   ================================ */
.controls-header {
  display: flex;
  justify-content: flex-end;
  align-items: center;
  margin-bottom: 0.625rem;
}

/* ================================
   SUBGRID CHILDREN LIST
   ================================ */
.sub-children-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-top: 0.5rem;
}

.sub-child-card {
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
}

.sub-child-card__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.5rem 0.75rem;
  background: var(--clr-bg-alt);
  border-bottom: 1px solid var(--clr-border);
  border-radius: var(--radius) var(--radius) 0 0;
  gap: 0.5rem;
}

.sub-child-card__label {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--clr-text);
}

.sub-child-card__remove {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 1.5rem;
  height: 1.5rem;
  background: none;
  border: 1px solid var(--clr-border);
  border-radius: 50%;
  font-size: 1rem;
  line-height: 1;
  color: var(--clr-text-muted);
  cursor: pointer;
  transition: color 0.15s ease, border-color 0.15s ease;
  padding: 0;
}

.sub-child-card__remove:hover:not(:disabled) {
  color: #dc2626;
  border-color: #dc2626;
}

.sub-child-card__remove:focus-visible {
  outline: 2px solid var(--clr-accent);
  outline-offset: 1px;
}

.sub-child-card__remove:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.sub-child-card__body {
  padding: 0.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.625rem;
}