body.frame-rate-tester-page {
  color-scheme: light;

  /* Base palette */
  --frame-page: #f4f6f8;
  --frame-surface: #ffffff;
  --frame-surface-soft: #f6f8fa;
  --frame-border: #d0d7de;
  --frame-text: #1f2328;
  --frame-muted: #57606a;
  --frame-accent: #0969da;
  --frame-accent-hover: #0757b5;
  --frame-on-accent: #ffffff;

  /* Feedback palette */
  --frame-success: #1a7f37;
  --frame-warning: #9a6700;
  --frame-danger: #cf222e;
  --frame-notice-text: #0550ae;
  --frame-notice-bg: #ddf4ff;
  --frame-notice-border: #b6e3ff;
  --frame-success-bg: #dafbe1;
  --frame-success-border: #aceebb;
  --frame-warning-bg: #fff8c5;
  --frame-warning-border: #eac54f;
  --frame-danger-bg: #ffebe9;
  --frame-danger-border: #ff8182;

  /* Measurement surface palette */
  --frame-test-surface: #0d1117;
  --frame-test-surface-soft: #161b22;
  --frame-test-text: #f0f6fc;
  --frame-test-muted: #b1bac4;
  --frame-test-accent: #58a6ff;
  --frame-test-accent-soft: rgba(88, 166, 255, 0.1);
  --frame-test-accent-glow: rgba(88, 166, 255, 0.16);
  --frame-test-accent-shadow: rgba(88, 166, 255, 0.75);
  --frame-test-overlay-border: rgba(255, 255, 255, 0.2);
  --frame-test-overlay-bg: rgba(13, 17, 23, 0.82);
  --frame-test-overlay-shadow: rgba(0, 0, 0, 0.28);
  --frame-test-progress-track: #30363d;

  /* Layout and component dimensions */
  --frame-shadow: 0 14px 36px rgba(31, 35, 40, 0.07);
  --frame-content-max-width: 1320px;
  --frame-page-gutter: 40px;
  --frame-page-gutter-mobile: 20px;
  --frame-panel-radius: 12px;
  --frame-panel-padding: 18px;
  --frame-panel-gap: 16px;
  --frame-control-height: 38px;
  --frame-control-radius: 8px;
  --frame-pill-radius: 999px;
  --frame-small-font-size: 0.9rem;
  --frame-result-meta-font-size: 0.82rem;
  --frame-measurement-min-height: 320px;
  --frame-measurement-min-height-mobile: 420px;
  --frame-chart-height: 260px;
  --frame-mobile-panel-padding: 14px;
  --frame-focus-ring: rgba(9, 105, 218, 0.24);
  margin: 0;
  min-height: 100vh;
  color: var(--frame-text);
  background: var(--frame-page);
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
}

/* Page foundation */
.frame-rate-tester,
.frame-rate-tester * {
  box-sizing: border-box;
}

body.frame-rate-tester-page > .frame-rate-main {
  width: min(var(--frame-content-max-width), calc(100% - var(--frame-page-gutter)));
  margin: 0 auto;
  padding-block: 40px;
  padding-inline: 0;
}

/* Page heading and navigation */
.frame-rate-tester .frame-rate-page-header {
  margin-block-end: 18px;
}

.frame-rate-tester :is(.frame-rate-page-title, .frame-rate-panel-title) {
  margin: 0;
}

.frame-rate-tester .frame-rate-page-title {
  font-size: clamp(1.7rem, 3vw, 2.2rem);
}

.frame-rate-tester .frame-rate-page-description {
  margin-block: 8px 0;
  margin-inline: 0;
  color: var(--frame-muted);
  line-height: 1.7;
}

.frame-rate-tester .breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-block-end: 12px;
  color: var(--frame-muted);
  font-size: var(--frame-small-font-size);
}

.frame-rate-tester a {
  color: var(--frame-accent);
  font-weight: 700;
  text-decoration: none;
}

.frame-rate-tester a:hover,
.frame-rate-tester a:focus-visible {
  text-decoration: underline;
}

/* Panels */
.frame-rate-tester :is(.frame-rate-panel-shell, .frame-rate-panel) {
  margin-block-end: var(--frame-panel-gap);
  border: 1px solid var(--frame-border);
  border-radius: var(--frame-panel-radius);
  background: var(--frame-surface);
  box-shadow: var(--frame-shadow);
}

.frame-rate-tester .frame-rate-notice {
  padding-block: 12px;
  padding-inline: 14px;
  border-color: var(--frame-notice-border);
  color: var(--frame-notice-text);
  background: var(--frame-notice-bg);
  line-height: 1.65;
}

.frame-rate-tester .frame-rate-panel {
  padding: var(--frame-panel-padding);
}

.frame-rate-tester .frame-rate-panel-heading {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 18px;
  margin-block-end: var(--frame-panel-gap);
}

.frame-rate-tester .frame-rate-panel-copy {
  min-width: 0;
}

.frame-rate-tester .frame-rate-panel-title {
  font-size: 1.08rem;
}

.frame-rate-tester .frame-rate-panel-description {
  margin-block: 6px 0;
  margin-inline: 0;
  color: var(--frame-muted);
  line-height: 1.6;
}

.frame-rate-tester .frame-rate-panel-actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
}

/* Controls */
.frame-rate-tester :is(button, select, input) {
  color: var(--frame-text);
  font: inherit;
}

.frame-rate-tester :is(button, select) {
  min-height: var(--frame-control-height);
  border: 1px solid var(--frame-border);
  border-radius: var(--frame-control-radius);
  background: var(--frame-surface-soft);
}

.frame-rate-tester button {
  padding-block: 7px;
  padding-inline: 13px;
  font-weight: 700;
  cursor: pointer;
}

.frame-rate-tester .frame-rate-primary-button {
  border-color: var(--frame-accent);
  color: var(--frame-on-accent);
  background: var(--frame-accent);
}

/* Settings and live status */
.frame-rate-tester .frame-rate-settings-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(180px, 1fr));
  gap: 12px;
}

.frame-rate-tester .frame-rate-setting-field {
  display: grid;
  align-content: center;
  gap: 7px;
  color: var(--frame-muted);
  font-size: var(--frame-small-font-size);
  font-weight: 700;
}

.frame-rate-tester .frame-rate-setting-field select {
  width: 100%;
  padding-block: 7px;
  padding-inline: 10px 36px;
}

.frame-rate-tester .frame-rate-check-field {
  display: flex;
  align-items: center;
  align-self: end;
  min-height: var(--frame-control-height);
  padding-block: 8px;
  padding-inline: 10px;
}

.frame-rate-tester .frame-rate-check-field input {
  margin: 0;
  accent-color: var(--frame-accent);
}

.frame-rate-tester .frame-rate-status-list {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px 20px;
  margin-block-start: 14px;
  padding-block: 11px;
  padding-inline: 12px;
  color: var(--frame-muted);
  font-size: var(--frame-small-font-size);
}

.frame-rate-tester .frame-rate-status-list strong {
  color: var(--frame-text);
}

.frame-rate-tester .frame-rate-message {
  margin-block: 12px 0;
  margin-inline: 0;
  padding-block: 10px;
  padding-inline: 12px;
  color: var(--frame-muted);
  line-height: 1.55;
}

.frame-rate-tester :is(
  .frame-rate-check-field,
  .frame-rate-status-list,
  .frame-rate-message,
  .frame-rate-result-card
) {
  border-radius: var(--frame-control-radius);
  background: var(--frame-surface-soft);
}

.frame-rate-tester :is(
  .frame-rate-check-field,
  .frame-rate-message,
  .frame-rate-result-card
) {
  border: 1px solid var(--frame-border);
}

/* Measurement surface */
.frame-rate-tester .frame-rate-measurement-panel {
  padding: 0;
  overflow: hidden;
}

.frame-rate-tester .frame-rate-measurement-panel > .frame-rate-panel-heading {
  margin: 0;
  padding: var(--frame-panel-padding);
}

.frame-rate-tester .frame-rate-measurement-surface {
  position: relative;
  min-height: var(--frame-measurement-min-height);
  overflow: hidden;
  border-block-start: 1px solid var(--frame-border);
  color: var(--frame-test-text);
  background: var(--frame-test-surface);
}

.frame-rate-tester .frame-rate-motion-stage {
  position: absolute;
  inset: 0;
  overflow: hidden;
}

.frame-rate-tester .frame-rate-motion-grid {
  position: absolute;
  inset: 0;
  opacity: 0.8;
  background:
    linear-gradient(var(--frame-test-accent-soft) 1px, transparent 1px) 0 0 / 32px 32px,
    linear-gradient(90deg, var(--frame-test-accent-soft) 1px, transparent 1px) 0 0 / 32px 32px,
    radial-gradient(circle at center, var(--frame-test-surface-soft), var(--frame-test-surface) 72%);
}

.frame-rate-tester .frame-rate-motion-marker,
.frame-rate-tester .frame-rate-motion-trail {
  --motion-x: 24px;
  position: absolute;
  top: 50%;
  left: 0;
  transform: translate3d(var(--motion-x), -50%, 0);
  will-change: transform;
}

.frame-rate-tester .frame-rate-motion-marker {
  width: 46px;
  height: 46px;
  border: 2px solid var(--frame-on-accent);
  border-radius: 50%;
  background: var(--frame-test-accent);
  box-shadow:
    0 0 0 8px var(--frame-test-accent-glow),
    0 0 28px var(--frame-test-accent-shadow);
}

.frame-rate-tester .frame-rate-motion-trail {
  width: 92px;
  height: 8px;
  border-radius: var(--frame-pill-radius);
  background: linear-gradient(90deg, transparent, var(--frame-test-accent-shadow));
}

.frame-rate-tester .frame-rate-surface-overlay {
  position: absolute;
  inset: auto 18px 18px;
  display: grid;
  gap: 9px;
  padding-block: 13px;
  padding-inline: 14px;
  border: 1px solid var(--frame-test-overlay-border);
  border-radius: 10px;
  background: var(--frame-test-overlay-bg);
  box-shadow: 0 10px 30px var(--frame-test-overlay-shadow);
}

.frame-rate-tester .frame-rate-surface-summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.frame-rate-tester .frame-rate-surface-overlay span {
  color: var(--frame-test-muted);
}

.frame-rate-tester .frame-rate-progress {
  --frame-progress: 0%;
  height: 6px;
  overflow: hidden;
  border-radius: var(--frame-pill-radius);
  background: var(--frame-test-progress-track);
}

.frame-rate-tester .frame-rate-progress::before {
  display: block;
  width: var(--frame-progress);
  height: 100%;
  border-radius: inherit;
  background: var(--frame-test-accent);
  content: "";
}

/* Results */
.frame-rate-tester .frame-rate-result-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 10px;
}

.frame-rate-tester .frame-rate-result-card {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: end;
  gap: 5px 8px;
  min-width: 0;
  padding-block: 13px;
  padding-inline: 13px;
}

.frame-rate-tester .frame-rate-result-label {
  grid-column: 1 / -1;
  color: var(--frame-muted);
  font-size: var(--frame-result-meta-font-size);
  font-weight: 700;
}

.frame-rate-tester .frame-rate-result-value {
  overflow: hidden;
  font-size: clamp(1.2rem, 2.4vw, 1.75rem);
  text-overflow: ellipsis;
  white-space: nowrap;
}

.frame-rate-tester .frame-rate-result-unit {
  padding-block-end: 3px;
  color: var(--frame-muted);
  font-size: var(--frame-result-meta-font-size);
}

/* Charts and guidance */
.frame-rate-tester .frame-rate-chart-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.frame-rate-tester .frame-rate-chart-grid canvas {
  display: block;
  width: 100%;
  height: var(--frame-chart-height);
  border: 1px solid var(--frame-border);
  border-radius: var(--frame-control-radius);
  background: var(--frame-test-surface);
}

.frame-rate-tester .frame-rate-guide-list {
  margin: 0;
  padding-inline-start: 1.4rem;
  color: var(--frame-muted);
  line-height: 1.8;
}

/* Interactive and measurement states */
.frame-rate-tester button:hover:not(:disabled) {
  border-color: var(--frame-accent);
  color: var(--frame-accent);
}

.frame-rate-tester button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.frame-rate-tester .frame-rate-primary-button:hover:not(:disabled) {
  border-color: var(--frame-accent-hover);
  color: var(--frame-on-accent);
  background: var(--frame-accent-hover);
}

.frame-rate-tester :is(button, select, input):focus-visible {
  outline: 3px solid var(--frame-focus-ring);
  outline-offset: 2px;
}

.frame-rate-tester .frame-rate-message[data-type="success"] {
  border-color: var(--frame-success-border);
  color: var(--frame-success);
  background: var(--frame-success-bg);
}

.frame-rate-tester .frame-rate-message[data-type="warning"] {
  border-color: var(--frame-warning-border);
  color: var(--frame-warning);
  background: var(--frame-warning-bg);
}

.frame-rate-tester .frame-rate-message[data-type="error"] {
  border-color: var(--frame-danger-border);
  color: var(--frame-danger);
  background: var(--frame-danger-bg);
}

.frame-rate-tester .frame-rate-measurement-surface.is-motion-disabled :is(
  .frame-rate-motion-marker,
  .frame-rate-motion-trail
) {
  left: calc(50% - 23px);
  transform: translate3d(0, -50%, 0);
}

.frame-rate-tester .frame-rate-measurement-surface:fullscreen {
  width: 100vw;
  height: 100vh;
  min-height: 100vh;
  border: 0;
}

.frame-rate-tester .frame-rate-measurement-surface:fullscreen .frame-rate-surface-overlay {
  inset:
    auto
    max(18px, env(safe-area-inset-right))
    max(18px, env(safe-area-inset-bottom))
    max(18px, env(safe-area-inset-left));
}

.frame-rate-tester .frame-rate-result-card[data-stability="excellent"] .frame-rate-result-value,
.frame-rate-tester .frame-rate-result-card[data-stability="good"] .frame-rate-result-value {
  color: var(--frame-success);
}

.frame-rate-tester .frame-rate-result-card[data-stability="fair"] .frame-rate-result-value {
  color: var(--frame-warning);
}

.frame-rate-tester .frame-rate-result-card[data-stability="unstable"] .frame-rate-result-value {
  color: var(--frame-danger);
}

/* Responsive layout */
/* Tablet and narrow desktop */
@media (max-width: 980px) {
  .frame-rate-tester .frame-rate-settings-grid,
  .frame-rate-tester .frame-rate-result-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .frame-rate-tester .frame-rate-status-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .frame-rate-tester .frame-rate-chart-grid {
    grid-template-columns: 1fr;
  }
}

/* Mobile */
@media (max-width: 700px) {
  body.frame-rate-tester-page > .frame-rate-main {
    width: min(100% - var(--frame-page-gutter-mobile), var(--frame-content-max-width));
    padding-block: 22px;
    padding-inline: 0;
  }

  .frame-rate-tester .frame-rate-panel {
    padding: var(--frame-mobile-panel-padding);
  }

  .frame-rate-tester .frame-rate-panel-heading {
    align-items: stretch;
    flex-direction: column;
  }

  .frame-rate-tester .frame-rate-panel-actions > button {
    flex: 1;
  }

  .frame-rate-tester :is(
    .frame-rate-settings-grid,
    .frame-rate-status-list,
    .frame-rate-result-grid
  ) {
    grid-template-columns: 1fr;
  }

  .frame-rate-tester .frame-rate-measurement-surface {
    min-height: var(--frame-measurement-min-height-mobile);
  }

  .frame-rate-tester .frame-rate-surface-overlay {
    inset: auto 10px 10px;
  }

  .frame-rate-tester .frame-rate-surface-summary {
    align-items: flex-start;
    flex-direction: column;
    gap: 4px;
  }
}

/* Motion accessibility */
@media (prefers-reduced-motion: reduce) {
  .frame-rate-tester .frame-rate-motion-marker,
  .frame-rate-tester .frame-rate-motion-trail {
    display: none;
  }
}