/**
 * Academic Atelier — tokens from DESIGN.md
 */
@import url("https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600&family=Manrope:wght@500;600;700&display=swap");

:root {
  --surface: #f8f9fa;
  --surface-container-low: #f3f4f5;
  --surface-container-lowest: #ffffff;
  --surface-container-high: #eceef1;
  --surface-bright: rgba(248, 249, 250, 0.8);
  --surface-tint: rgba(25, 28, 29, 0.08);
  --primary: #004493;
  --primary_container: #005bc0;
  --on_primary: #ffffff;
  --on_surface: #191c1d;
  --on_secondary_container: #1a1c1e;
  --secondary_container: #dce3e8;
  --outline_variant: rgba(195, 198, 214, 0.15);
  --tertiary: #6b5a4a;
  --success: #1b6e3a;
  --error: #b3261e;
  /* Filled destructive — lighter red, still readable with white label */
  --danger-fill: #d14b42;
  --on-danger-fill: #ffffff;
  --danger-fill-hover: #b33f37;
  --ambient-shadow: 0 20px 40px rgba(25, 28, 29, 0.06);
  --card-raise:
    0 1px 2px rgba(25, 28, 29, 0.05),
    0 4px 12px rgba(25, 28, 29, 0.04),
    0 14px 32px rgba(25, 28, 29, 0.06);
  --card-edge: color-mix(in srgb, var(--on_surface) 9%, transparent);
  --primary-hover-mix: black;
  --shadow-footer-up: 0 -12px 40px rgba(25, 28, 29, 0.08);
  --radius-md: 0.75rem;
  --radius-full: 9999px;
  --font-display: "Manrope", system-ui, sans-serif;
  --font-body: "Inter", system-ui, sans-serif;
  --tracking-label: 0.05em;
  --tracking-display: -0.02em;
}

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

html {
  font-size: 100%;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font-body);
  font-weight: 400;
  color: var(--on_surface);
  background: var(--surface-container-low);
  line-height: 1.5;
}

/* —— Layout —— */
.app-shell {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.top-bar {
  position: sticky;
  top: 0;
  z-index: 20;
  padding: 1rem 1.5rem 1.25rem;
  background: color-mix(in srgb, var(--surface-container-lowest) 80%, transparent);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.quiz-head-sticky {
  position: sticky;
  top: 0;
  z-index: 25;
  background: var(--surface-container-low);
  padding-bottom: 0.5rem;
}

.quiz-sticky-top {
  margin-bottom: 1.15rem;
}

.quiz-sticky-nav {
  padding-top: 1.1rem;
  margin-top: 0.25rem;
  background: color-mix(in srgb, var(--surface-container-high) 28%, var(--surface-container-lowest));
  margin-left: -1.75rem;
  margin-right: -1.75rem;
  margin-bottom: -2rem;
  padding-left: 1.75rem;
  padding-right: 1.75rem;
  padding-bottom: 1.5rem;
  border-radius: 0 0 var(--radius-md) var(--radius-md);
}

.quiz-outer {
  max-width: min(100%, 72rem);
  margin: 0 auto;
  width: 100%;
}

.quiz-columns {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
  align-items: start;
  margin-top: 0.75rem;
  padding: 1.25rem 1.35rem 1.5rem;
  background: var(--surface-container-lowest);
  border-radius: var(--radius-md);
  box-shadow: var(--card-raise);
  outline: 1px solid var(--card-edge);
  outline-offset: 0;
}

@media (min-width: 960px) {
  .quiz-columns {
    grid-template-columns: minmax(0, 1fr) 15.5rem;
    gap: 1.75rem;
  }
}

@media (min-width: 1100px) {
  .quiz-columns {
    grid-template-columns: minmax(0, 1fr) 17.5rem;
  }
}

.quiz-main-column {
  min-width: 0;
}

.quiz-sidebar {
  min-width: 0;
}

.quiz-sidebar-inner {
  position: sticky;
  top: 1rem;
  max-height: min(72vh, 24rem);
  display: flex;
  flex-direction: column;
  padding: 0.85rem 0.85rem 0.95rem;
  margin: 0;
  background: color-mix(in srgb, var(--surface-container-high) 55%, var(--surface-container-lowest));
  border-radius: calc(var(--radius-md) - 2px);
  outline: 1px solid color-mix(in srgb, var(--on_surface) 6%, transparent);
  outline-offset: 0;
}

@media (min-width: 960px) {
  .quiz-sidebar-inner {
    top: calc(1rem + env(safe-area-inset-top, 0px));
    max-height: min(76vh, 26rem);
  }
}

/* Mobile: question column first; jump grid below. Bottom dock for controls. */
@media (max-width: 959px) {
  .quiz-sidebar-inner {
    max-height: 17rem;
    padding: 0.65rem 0.75rem 0.75rem;
  }

  .main-stage:has(#view-quiz:not(.hidden)) {
    padding-bottom: calc(10.5rem + env(safe-area-inset-bottom, 0px));
  }

  .quiz-head-sticky {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    top: auto;
    z-index: 40;
    padding: 0;
    padding-bottom: env(safe-area-inset-bottom, 0px);
    background: color-mix(in srgb, var(--surface-container-lowest) 94%, transparent);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border-top: 1px solid var(--card-edge);
    box-shadow: 0 -10px 32px rgba(25, 28, 29, 0.1);
  }

  html.theme-dark .quiz-head-sticky {
    box-shadow: 0 -10px 32px rgba(0, 0, 0, 0.45);
  }

  .quiz-sticky-card.card {
    padding: 0.6rem 0.85rem 0.75rem;
    margin: 0;
    max-width: 100%;
    border-radius: 0;
    box-shadow: none;
    outline: none;
    background: transparent;
  }

  .quiz-sticky-top {
    margin-bottom: 0.4rem;
  }

  .quiz-sticky-top .brand-mark {
    display: none;
  }

  .quiz-head-sticky .btn-theme-compact,
  .quiz-head-sticky .theme-switch-compact {
    display: none;
  }

  .quiz-head-sticky .brand-row {
    margin-bottom: 0.35rem;
  }

  .quiz-head-sticky .brand-row-end {
    flex: 1;
    min-width: 0;
    justify-content: space-between;
    gap: 0.35rem;
  }

  .quiz-head-sticky .quiz-timer {
    font-size: 0.75rem;
    min-width: 2.75rem;
  }

  .quiz-head-sticky #progress-meta {
    font-size: 0.75rem;
    flex: 1;
    text-align: right;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  .quiz-head-sticky .progress-wrap {
    height: 4px;
  }

  .quiz-sticky-nav {
    margin: 0;
    padding: 0.45rem 0 0;
    margin-left: 0;
    margin-right: 0;
    margin-bottom: 0;
    padding-left: 0;
    padding-right: 0;
    padding-bottom: 0;
    background: transparent;
    border-radius: 0;
    gap: 0.35rem;
    justify-content: space-between;
  }

  .quiz-sticky-nav .btn {
    font-size: 0.75rem;
    font-weight: 600;
    padding: 0.5rem 0.4rem;
    flex: 1 1 0;
    min-width: 0;
  }

  .quiz-sticky-nav .btn-primary {
    flex: 1.2 1 0;
  }

  .quiz-columns {
    margin-top: 0;
  }
}

.top-bar-inner {
  max-width: 52rem;
  margin: 0 auto;
}

.brand-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1rem;
}

.brand-row-end {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.btn-theme-compact {
  font-size: 0.8125rem;
  padding: 0.35rem 0.65rem;
  flex-shrink: 0;
}

.theme-switch {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  font-size: 0.8125rem;
  color: color-mix(in srgb, var(--on_surface) 82%, transparent);
}

.theme-switch input {
  position: absolute;
  opacity: 0;
  width: 1px;
  height: 1px;
  pointer-events: none;
}

.theme-switch-label {
  font-weight: 600;
  letter-spacing: 0.01em;
}

.theme-switch-track {
  width: 2.6rem;
  height: 1.5rem;
  border-radius: 9999px;
  background: var(--surface-container-high);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--on_surface) 16%, transparent);
  position: relative;
  transition: background 0.2s ease;
}

.theme-switch-track::after {
  content: "";
  position: absolute;
  top: 0.14rem;
  left: 0.16rem;
  width: 1.2rem;
  height: 1.2rem;
  border-radius: 50%;
  background: var(--surface-container-lowest);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.22);
  transition: transform 0.2s ease;
}

.theme-switch input:checked + .theme-switch-track {
  background: color-mix(in srgb, var(--primary) 26%, var(--surface-container-high));
}

.theme-switch input:checked + .theme-switch-track::after {
  transform: translateX(1.08rem);
}

.theme-switch input:focus-visible + .theme-switch-track {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

.theme-switch-compact .theme-switch-label {
  display: none;
}

.quiz-timer {
  font-family: var(--font-body);
  font-size: 0.8125rem;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  color: var(--on_surface);
  min-width: 3.25rem;
  text-align: right;
}

.brand-mark {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 0.75rem;
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
  color: var(--primary);
}

.meta-muted {
  font-size: 0.8125rem;
  color: color-mix(in srgb, var(--on_surface) 55%, transparent);
}

/* Progress: 8px track, gradient fill */
.progress-wrap {
  height: 8px;
  border-radius: var(--radius-full);
  background: var(--secondary_container);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  width: 0%;
  border-radius: var(--radius-full);
  background: linear-gradient(
    135deg,
    var(--primary) 0%,
    var(--primary_container) 100%
  );
  transition: width 0.35s ease;
}

.main-stage {
  flex: 1;
  padding: 2rem 1.5rem 4rem;
  max-width: 52rem;
  margin: 0 auto;
  width: 100%;
}

.main-stage:has(#view-quiz:not(.hidden)) {
  max-width: min(100%, 72rem);
}

/* —— Typography —— */
.display-intro {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(2rem, 5vw, 3.5rem);
  letter-spacing: var(--tracking-display);
  line-height: 1.15;
  margin: 0 0 1rem;
  color: var(--on_surface);
}

.lede {
  font-size: 1.0625rem;
  color: color-mix(in srgb, var(--on_surface) 72%, transparent);
  margin: 0 0 2.5rem;
  max-width: 36rem;
}

.title-lg {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.375rem;
  line-height: 1.35;
  letter-spacing: -0.01em;
  margin: 0 0 1.75rem;
  color: var(--on_surface);
}

.label-md {
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
  color: color-mix(in srgb, var(--on_surface) 50%, transparent);
}

.section-label {
  display: block;
  width: fit-content;
  padding: 0.28rem 0.6rem;
  border-radius: var(--radius-full);
  color: var(--primary);
  background: color-mix(in srgb, var(--primary) 12%, var(--surface-container-lowest));
  letter-spacing: 0.06em;
}

/* —— Surfaces —— */
.card {
  background: var(--surface-container-lowest);
  border-radius: var(--radius-md);
  padding: 1.75rem 1.75rem 2rem;
  box-shadow: var(--card-raise);
  outline: 1px solid var(--card-edge);
  outline-offset: 0;
}

.card + .card {
  margin-top: 1.5rem;
}

/* —— Buttons —— */
.btn {
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 0.9375rem;
  padding: 0.75rem 1.5rem;
  border: none;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: background 0.2s ease, box-shadow 0.2s ease;
}

.btn-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
}

.btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.btn-primary {
  background: var(--primary);
  color: var(--on_primary);
  box-shadow: var(--ambient-shadow);
}

.btn-primary:hover:not(:disabled) {
  background: color-mix(in srgb, var(--primary) 88%, var(--primary-hover-mix));
}

.btn-secondary {
  background: var(--surface-container-high);
  color: var(--on_secondary_container);
}

.btn-secondary:hover:not(:disabled) {
  background: color-mix(in srgb, var(--surface-container-high) 85%, var(--on_surface));
}

.btn-danger {
  background: var(--danger-fill);
  color: var(--on-danger-fill);
  box-shadow: var(--ambient-shadow);
}

.btn-danger:hover:not(:disabled) {
  background: var(--danger-fill-hover);
}

.btn-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 2rem;
}

/* —— Options (radio list, choices shuffled per question in JS) —— */
.options {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.options--radio .option-radio {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  margin: 0;
  cursor: pointer;
}

.options--radio .option-radio-input {
  margin: 0.2rem 0 0;
  flex-shrink: 0;
  width: 1.125rem;
  height: 1.125rem;
  accent-color: var(--primary);
  cursor: pointer;
}

.options--radio .option-radio-input:disabled {
  cursor: default;
}

.options--radio .option-radio-text {
  flex: 1;
  min-width: 0;
  line-height: 1.45;
}

.option-btn {
  display: block;
  width: 100%;
  text-align: left;
  font-family: var(--font-body);
  font-size: 0.9375rem;
  padding: 1rem 1.125rem;
  border: none;
  border-radius: var(--radius-md);
  background: var(--surface-container-low);
  color: var(--on_surface);
  cursor: pointer;
  transition: background 0.2s ease, box-shadow 0.2s ease;
}

.option-radio.option-btn:hover:not(:has(input:disabled)) {
  background: var(--surface-container-high);
}

.option-btn:focus-within {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

.option-btn:has(input:disabled) {
  cursor: default;
}

.option-btn.selected {
  background: color-mix(in srgb, var(--primary) 12%, var(--surface-container-lowest));
  color: var(--on_surface);
}

.option-btn.correct-reveal {
  background: color-mix(in srgb, var(--success) 16%, var(--surface-container-lowest));
  box-shadow: inset 0 0 0 1.5px color-mix(in srgb, var(--success) 45%, transparent);
  color: var(--on_surface);
}

.option-btn.incorrect-reveal {
  background: color-mix(in srgb, var(--error) 16%, var(--surface-container-lowest));
  box-shadow: inset 0 0 0 1.5px color-mix(in srgb, var(--error) 42%, transparent);
  color: var(--on_surface);
}

.option-btn.incorrect-reveal .option-radio-text {
  color: var(--on_surface);
}

/* —— Confidence chips —— */
.confidence-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  margin-top: 2rem;
  padding-top: 2rem;
}

.confidence-label {
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
  color: color-mix(in srgb, var(--on_surface) 45%, transparent);
  width: 100%;
  margin-bottom: 0.25rem;
}

.chip {
  font-family: var(--font-body);
  font-size: 0.8125rem;
  font-weight: 500;
  padding: 0.45rem 0.9rem;
  border: none;
  border-radius: var(--radius-full);
  cursor: pointer;
  background: var(--surface-container-high);
  color: var(--on_surface);
  transition: background 0.2s ease;
}

.chip:hover {
  background: color-mix(in srgb, var(--surface-container-high) 88%, var(--on_surface));
}

.chip[data-level="confident"] {
  background: color-mix(in srgb, var(--tertiary) 10%, var(--surface-container-lowest));
}

.chip[data-level="confident"].active {
  background: color-mix(in srgb, var(--tertiary) 22%, var(--surface-container-lowest));
}

.chip[data-level="unsure"] {
  background: color-mix(in srgb, var(--primary) 8%, var(--surface-container-lowest));
}

.chip[data-level="unsure"].active {
  background: color-mix(in srgb, var(--primary) 18%, var(--surface-container-lowest));
}

.chip[data-level="review"] {
  background: color-mix(in srgb, var(--error) 10%, var(--surface-container-lowest));
}

.chip[data-level="review"].active {
  background: color-mix(in srgb, var(--error) 20%, var(--surface-container-lowest));
}

/* —— Results —— */
.view-results {
  position: relative;
  padding-bottom: 6.25rem;
}

.results-body {
  display: grid;
  gap: 1.5rem;
  padding-bottom: 1rem;
}

.results-hero {
  background: color-mix(in srgb, var(--surface-container-lowest) 84%, var(--surface-container-high));
  box-shadow: var(--card-raise);
  outline: none;
  padding-bottom: 1.5rem;
}

.results-footer-hint {
  font-size: 0.8125rem;
  margin: 0 0 1rem;
  max-width: 32rem;
  line-height: 1.45;
}

.results-skip-link {
  font-weight: 600;
  color: var(--primary);
  text-decoration: none;
}

.results-skip-link:hover {
  text-decoration: underline;
}

.results-footer-hint-sep {
  color: color-mix(in srgb, var(--on_surface) 45%, transparent);
}

.results-review-heading {
  margin: 0;
}

.results-review-list {
  display: grid;
  gap: 1.5rem;
}

.results-footer {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 50;
  padding: 0.875rem 1.5rem calc(0.875rem + env(safe-area-inset-bottom, 0px));
  background: color-mix(in srgb, var(--surface-container-lowest) 88%, transparent);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  box-shadow: var(--shadow-footer-up);
  outline: none;
}

.results-footer-inner {
  max-width: 52rem;
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
}

.score-ring {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 3rem;
  letter-spacing: var(--tracking-display);
  color: var(--primary);
  margin: 0 0 0.5rem;
}

.results-summary {
  font-size: 1.0625rem;
  color: color-mix(in srgb, var(--on_surface) 75%, transparent);
  margin-bottom: 2rem;
}

.review-item {
  padding: 1.35rem 1.4rem 1.5rem;
  margin: 0;
  background: color-mix(in srgb, var(--surface-container-lowest) 80%, var(--surface-container-high));
  outline: none;
}

.review-item + .review-item {
  margin-top: 0;
}

.hidden {
  display: none !important;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

.status-banner {
  margin-top: 1.25rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 500;
}

.status-banner.ok {
  background: color-mix(in srgb, var(--success) 12%, var(--surface-container-lowest));
  color: var(--on_surface);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--success) 22%, transparent);
}

.status-banner.bad {
  background: color-mix(in srgb, var(--error) 12%, var(--surface-container-lowest));
  color: var(--on_surface);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--error) 22%, transparent);
}

/* —— Select (ghost border) —— */
select.field-select {
  font-family: var(--font-body);
  font-size: 0.9375rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--outline_variant);
  background: var(--surface-container-lowest);
  color: var(--on_surface);
  max-width: 28rem;
  width: 100%;
  cursor: pointer;
}

select.field-select:focus {
  outline: none;
  border-color: var(--primary);
  background: var(--surface-container-lowest);
}

.quiz-body {
  padding-top: 0.25rem;
}

.explore-nav {
  margin-bottom: 1.75rem;
}

.explore-nav-hint .kbd-hint {
  display: inline-block;
  font-family: var(--font-body);
  font-size: 0.8125rem;
  font-weight: 600;
  padding: 0.1rem 0.35rem;
  margin: 0 0.1rem;
  border-radius: 0.25rem;
  background: var(--surface-container-high);
  color: var(--on_surface);
}

.nav-toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
}

.question-jump {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  max-height: 12rem;
  overflow-y: auto;
  padding: 0.25rem 0 0.5rem;
}

.question-jump--side {
  flex: 1;
  min-height: 0;
  max-height: 17rem;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(2.35rem, 1fr));
  gap: 0.35rem;
  align-content: start;
  overflow-y: auto;
  padding: 0.1rem 0.1rem 0.2rem 0;
  -webkit-overflow-scrolling: touch;
}

@media (min-width: 960px) {
  .question-jump--side {
    grid-template-columns: repeat(4, 1fr);
    max-height: 18rem;
  }
}

@media (max-width: 959px) {
  .question-jump--side {
    max-height: 9.5rem;
  }
}

.jump-btn {
  font-family: var(--font-body);
  font-size: 0.8125rem;
  font-weight: 600;
  min-width: 2.5rem;
  padding: 0.45rem 0.5rem;
  border: none;
  border-radius: var(--radius-md);
  background: var(--surface-container-low);
  color: var(--on_surface);
  cursor: pointer;
  transition: background 0.2s ease;
}

.jump-btn:hover {
  background: var(--surface-container-high);
}

.jump-btn.jump-btn--correct:not(.jump-btn--current) {
  background: color-mix(in srgb, var(--success) 18%, var(--surface-container-lowest));
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--success) 35%, transparent);
  color: var(--on_surface);
}

.jump-btn.jump-btn--correct:not(.jump-btn--current):hover {
  background: color-mix(in srgb, var(--success) 26%, var(--surface-container-lowest));
}

.jump-btn.jump-btn--wrong:not(.jump-btn--current) {
  background: color-mix(in srgb, var(--error) 16%, var(--surface-container-lowest));
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--error) 38%, transparent);
  color: var(--on_surface);
}

.jump-btn.jump-btn--wrong:not(.jump-btn--current):hover {
  background: color-mix(in srgb, var(--error) 24%, var(--surface-container-lowest));
}

.jump-btn.jump-btn--answered:not(.jump-btn--current) {
  background: color-mix(in srgb, var(--primary) 14%, var(--surface-container-lowest));
  color: var(--on_surface);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--primary) 38%, transparent);
}

.jump-btn.jump-btn--current {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary_container) 100%);
  color: var(--on_primary);
  box-shadow: var(--ambient-shadow);
}

.option-btn.exam-selected {
  background: color-mix(in srgb, var(--primary) 14%, var(--surface-container-lowest));
  box-shadow: inset 0 0 0 2px color-mix(in srgb, var(--primary) 45%, transparent);
}

.jump-btn:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

.question-history {
  font-size: 0.8125rem;
  margin: 0 0 1rem;
}

.stats-panel .stats-summary {
  font-size: 0.9375rem;
  line-height: 1.55;
  color: color-mix(in srgb, var(--on_surface) 85%, transparent);
}

.stats-panel .stats-summary strong {
  color: var(--on_surface);
  font-weight: 600;
}

.stats-attempts-wrap {
  margin-top: 0.25rem;
}

.stats-attempts {
  list-style: none;
  margin: 0;
  padding: 0;
}

.stats-attempts li {
  font-size: 0.875rem;
  padding: 0.65rem 0;
  color: color-mix(in srgb, var(--on_surface) 78%, transparent);
}

.stats-attempts li + li {
  margin-top: 0.5rem;
}

.stats-attempts time {
  color: color-mix(in srgb, var(--on_surface) 55%, transparent);
  font-size: 0.8125rem;
  display: block;
  margin-bottom: 0.2rem;
}

/* —— Flash cards —— */
.flash-layout {
  max-width: 52rem;
}

.flash-topbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.flash-controls {
  display: grid;
  gap: 1.25rem;
  margin-bottom: 1.25rem;
}

/* 3D context lives here. Faces will be `.card` elements so the whole visible box rotates. */
.flash-card {
  position: relative;
  perspective: 1200px;
  cursor: pointer;
  user-select: none;
}

.flash-card-inner {
  position: relative;
  transform-style: preserve-3d;
  transition: transform 420ms ease;
  height: clamp(13.5rem, 38vh, 22rem);
  min-height: 12rem;
  will-change: transform;
}

.flash-card.is-flipped .flash-card-inner {
  transform: rotateY(180deg);
}

.flash-face {
  position: absolute;
  inset: 0;
  box-sizing: border-box;
  padding: 0; /* Override default `.card` padding to let `.flash-face-body` handle scrolling */
  margin: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  transform: translateZ(1px);
}

/* Prevent global `.card + .card` spacing from offsetting the back face. */
.flash-card-inner > .flash-face + .flash-face {
  margin-top: 0;
}

.flash-face-body {
  height: 100%;
  box-sizing: border-box;
  padding: 1.25rem 1.35rem 1.35rem;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  position: relative;
}

.flash-face-body::after {
  content: "flip";
  position: absolute;
  top: 0.9rem;
  right: 0.95rem;
  font-size: 0.68rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: color-mix(in srgb, var(--on_surface) 48%, transparent);
}

.flash-hint {
  text-align: center;
  margin: 0.6rem 0 0;
}

.flash-face .title-lg {
  margin-bottom: 1rem;
}

.flash-face-back {
  transform: rotateY(180deg) translateZ(1px);
}

.flash-nav-row {
  display: flex;
  justify-content: center;
  gap: 1rem;
  margin-top: 1rem;
  margin-bottom: 0.5rem;
}

.flash-arrow-btn {
  min-width: 3.25rem;
  padding-left: 1rem;
  padding-right: 1rem;
  font-size: 1.25rem;
  line-height: 1;
}

@media (min-width: 640px) {
  .main-stage {
    padding-left: 2rem;
    padding-right: 2rem;
  }
}

/* —— Dark theme (DESIGN-DARK.md: primary #1A73E8, secondary #5F6368) —— */
html.theme-dark {
  color-scheme: dark;
  --surface: #121212;
  --surface-container-low: #1c1b1f;
  --surface-container-lowest: #252329;
  --surface-container-high: #2d2c31;
  --surface-bright: rgba(28, 27, 31, 0.88);
  --surface-tint: rgba(255, 255, 255, 0.08);
  --primary: #1a73e8;
  --primary_container: #4285f4;
  --on_primary: #ffffff;
  --on_surface: #e8eaed;
  --on_secondary_container: #e8eaed;
  --secondary_container: #3c4043;
  --outline_variant: rgba(232, 234, 237, 0.14);
  --tertiary: #a08b7a;
  --success: #81c995;
  --error: #f28b82;
  /* Dark UI: lighter red fill */
  --danger-fill: #ef6a65;
  --on-danger-fill: #ffffff;
  --danger-fill-hover: #e8554f;
  --ambient-shadow: 0 20px 40px rgba(0, 0, 0, 0.45);
  --card-raise:
    0 1px 2px rgba(0, 0, 0, 0.35),
    0 4px 12px rgba(0, 0, 0, 0.28),
    0 14px 32px rgba(0, 0, 0, 0.38);
  --card-edge: color-mix(in srgb, var(--on_surface) 14%, transparent);
  --primary-hover-mix: white;
  --shadow-footer-up: 0 -12px 40px rgba(0, 0, 0, 0.55);
}