/* ---------- Design tokens ---------- */
:root {
  /* Cool "slate" neutrals instead of flat grey */
  --dk-bg: #f8fafc;
  --dk-surface: #ffffff;
  --dk-text: #0f172a;
  --dk-text-2: #334155;
  --dk-muted: #64748b;
  --dk-faint: #94a3b8;
  --dk-border: #e2e8f0;
  --dk-border-strong: #cbd5e1;
  --dk-subtle: #f1f5f9;

  /* One accent colour (indigo) */
  --dk-accent: #4f46e5;
  --dk-accent-hover: #4338ca;
  --dk-accent-active: #3730a3;
  --dk-accent-soft: #eef2ff;
  --dk-accent-ring: rgba(79, 70, 229, .22);

  --dk-radius: 12px;
  --dk-shadow: 0 1px 2px rgba(15, 23, 42, .04), 0 1px 3px rgba(15, 23, 42, .06);
  --dk-shadow-lg: 0 10px 30px -12px rgba(15, 23, 42, .18);

  /* Default tone; decks and feature cards override it with .tone-N */
  --tone: var(--dk-accent);
  --tone-soft: var(--dk-accent-soft);

  --bs-body-font-family: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --bs-body-color: var(--dk-text);
  --bs-body-bg: var(--dk-bg);
  --bs-border-color: var(--dk-border);
  --bs-secondary-color: var(--dk-muted);
  --bs-link-color-rgb: 79, 70, 229;
  --bs-link-hover-color-rgb: 55, 48, 163;
  --bs-border-radius: 8px;
  --bs-border-radius-lg: 10px;
}

html {
  font-size: 15px;
}

@media (min-width: 768px) {
  html {
    font-size: 16px;
  }
}

body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, h5 {
  font-weight: 600;
  letter-spacing: -0.02em;
}

a {
  text-underline-offset: 3px;
}

/* ---------- Header ---------- */
.site-header {
  background: rgba(255, 255, 255, .85);
  backdrop-filter: saturate(180%) blur(8px);
  border-bottom: 1px solid var(--dk-border);
}

.navbar {
  padding-block: .75rem;
}

.navbar-brand {
  display: flex;
  align-items: center;
  gap: .5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--dk-text);
}

.brand-mark {
  display: block;
  width: 28px;
  height: 28px;
}

.navbar .nav-link {
  color: var(--dk-muted);
  font-weight: 500;
  font-size: .95rem;
  padding-inline: .85rem !important;
  border-radius: 8px;
  transition: color .15s, background-color .15s;
}

.navbar .nav-link:hover {
  color: var(--dk-text);
  background: var(--dk-subtle);
}

.navbar .nav-link.active {
  color: var(--dk-text);
}

.navbar-toggler:focus {
  box-shadow: none;
}

.user-chip {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  color: var(--dk-text);
  font-size: .9rem;
  font-weight: 500;
  text-decoration: none;
  padding: .25rem .5rem .25rem .25rem;
  border-radius: 999px;
}

.user-chip:hover {
  background: var(--dk-subtle);
}

.user-avatar {
  display: inline-grid;
  place-items: center;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--dk-subtle);
  border: 1px solid var(--dk-border);
  font-size: .8rem;
  font-weight: 600;
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--dk-border);
  background: var(--dk-surface);
  color: var(--dk-muted);
  font-size: .875rem;
  padding-block: 1.5rem;
}

.site-footer a {
  color: var(--dk-muted);
  text-decoration: none;
}

.site-footer a:hover {
  color: var(--dk-text);
}

/* ---------- Buttons ---------- */
.btn {
  font-weight: 500;
  border-radius: 8px;
  transition: background-color .15s, border-color .15s, color .15s, box-shadow .15s;
}

.btn-lg {
  padding: .7rem 1.4rem;
  font-size: 1rem;
  border-radius: 10px;
}

.btn-dark {
  --bs-btn-bg: var(--dk-accent);
  --bs-btn-border-color: var(--dk-accent);
  --bs-btn-hover-bg: var(--dk-accent-hover);
  --bs-btn-hover-border-color: var(--dk-accent-hover);
  --bs-btn-active-bg: var(--dk-accent-active);
  --bs-btn-active-border-color: var(--dk-accent-active);
  --bs-btn-disabled-bg: var(--dk-accent);
  --bs-btn-disabled-border-color: var(--dk-accent);
}

.btn-light {
  --bs-btn-bg: var(--dk-surface);
  --bs-btn-color: var(--dk-text);
  --bs-btn-border-color: var(--dk-border);
  --bs-btn-hover-bg: var(--dk-subtle);
  --bs-btn-hover-border-color: var(--dk-border-strong);
  --bs-btn-active-bg: var(--dk-border);
  --bs-btn-active-border-color: var(--dk-border-strong);
}

.btn:focus-visible,
.form-control:focus,
.form-check-input:focus {
  border-color: var(--dk-accent);
  box-shadow: 0 0 0 3px var(--dk-accent-ring);
}

/* ---------- Forms ---------- */
.form-control {
  border-radius: 8px;
  border-color: var(--dk-border);
}

.form-floating > .form-control-plaintext::placeholder,
.form-floating > .form-control::placeholder {
  color: transparent;
}

.form-check-input:checked {
  background-color: var(--dk-accent);
  border-color: var(--dk-accent);
}

.text-danger {
  font-size: .85rem;
}

/* ---------- Cards / surfaces ---------- */
.card,
.surface {
  background: var(--dk-surface);
  border: 1px solid var(--dk-border);
  border-radius: var(--dk-radius);
  box-shadow: var(--dk-shadow);
}

/* ---------- Home ---------- */
.hero {
  padding: 3.5rem 1rem 3rem;
  border-radius: 20px;
  background:
    radial-gradient(60% 80% at 50% 0%, #ffffff 0%, rgba(255, 255, 255, 0) 70%),
    linear-gradient(180deg, #eef2ff 0%, #f8fafc 100%);
  border: 1px solid var(--dk-border);
}

@media (min-width: 768px) {
  .hero {
    padding: 5rem 2rem 4.5rem;
  }
}

.eyebrow {
  display: inline-block;
  margin-bottom: 1rem;
  padding: .3rem .75rem;
  border-radius: 999px;
  border: 1px solid var(--dk-border);
  background: var(--dk-surface);
  color: var(--dk-muted);
  font-size: .8rem;
  font-weight: 500;
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.25rem);
  font-weight: 700;
  letter-spacing: -0.035em;
  margin-bottom: .75rem;
}

.hero-lead {
  max-width: 34rem;
  margin: 0 auto 2rem;
  color: var(--dk-muted);
  font-size: 1.125rem;
}

.section {
  padding-block: 3.5rem 1rem;
}

.section-title {
  font-size: 1.75rem;
  margin-bottom: .5rem;
}

.flashcard {
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: .5rem;
  padding: 1.5rem;
  background: var(--dk-surface);
  border: 1px solid var(--dk-border);
  border-radius: var(--dk-radius);
  box-shadow: var(--dk-shadow);
  transition: box-shadow .2s, transform .2s;
}

.flashcard:hover {
  box-shadow: var(--dk-shadow-lg);
  transform: translateY(-2px);
}

.flashcard-word {
  font-size: 1.25rem;
  margin: 0;
}

.flashcard-definition {
  flex-grow: 1;
  margin: 0 0 .5rem;
  color: var(--dk-muted);
  transition: filter .25s;
}

.flashcard-definition.is-hidden {
  filter: blur(6px);
  user-select: none;
}

.cta {
  margin-top: 3rem;
  padding: 3rem 1rem;
  border-radius: 20px;
  background: var(--dk-surface);
  border: 1px solid var(--dk-border);
}

/* ---------- Auth pages ---------- */
.auth-card {
  max-width: 420px;
  margin: 0 auto;
  padding: 2rem;
  background: var(--dk-surface);
  border: 1px solid var(--dk-border);
  border-radius: 16px;
  box-shadow: var(--dk-shadow);
}

.auth-card h1 {
  font-size: 1.5rem;
  margin-bottom: .25rem;
}

.auth-links {
  display: flex;
  flex-direction: column;
  gap: .35rem;
  margin-top: 1.25rem;
  font-size: .9rem;
}

.auth-links a {
  color: var(--dk-muted);
}

.auth-links a:hover {
  color: var(--dk-text);
}

/* ---------- App pages ---------- */
.page-header {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: flex-end;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.page-title {
  font-size: 1.75rem;
  margin-bottom: .25rem;
}

.back-link {
  display: inline-block;
  margin-bottom: 1rem;
  color: var(--dk-muted);
  font-size: .9rem;
  text-decoration: none;
}

.back-link:hover {
  color: var(--dk-text);
}

.surface {
  padding: 1rem;
}

.inline-form {
  display: flex;
  gap: .5rem;
}

.card-form {
  padding: 1.25rem;
}

.notice {
  margin-bottom: 1rem;
  padding: .75rem 1rem;
  border-radius: 10px;
  border: 1px solid;
  font-size: .9rem;
}

.notice-error {
  color: #b91c1c;
  background: #fef2f2;
  border-color: #fecaca;
}

.notice-success {
  color: #15803d;
  background: #f0fdf4;
  border-color: #bbf7d0;
}

.empty-state {
  padding: 3rem 1rem;
  text-align: center;
  border: 1px dashed var(--dk-border-strong);
  border-radius: var(--dk-radius);
}

.empty-icon {
  font-size: 2rem;
  margin-bottom: .5rem;
}

/* Deck tiles */
.deck-tile {
  position: relative;
  height: 100%;
  display: flex;
  flex-direction: column;
  gap: .25rem;
  padding: 1.25rem;
  background: var(--dk-surface);
  border: 1px solid var(--dk-border);
  border-radius: var(--dk-radius);
  box-shadow: var(--dk-shadow);
  transition: box-shadow .2s, transform .2s, border-color .2s;
}

.deck-tile:hover {
  border-color: var(--dk-border-strong);
  box-shadow: var(--dk-shadow-lg);
  transform: translateY(-2px);
}

.deck-tile-name {
  color: var(--dk-text);
  font-weight: 600;
  font-size: 1.1rem;
  text-decoration: none;
  overflow-wrap: anywhere;
}

.deck-tile-action {
  position: relative;
  z-index: 2;
  align-self: flex-start;
  margin-top: .75rem;
}

/* Card list */
.card-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.card-row {
  padding: .9rem 1.25rem;
  border-bottom: 1px solid var(--dk-border);
}

.card-row:last-child {
  border-bottom: 0;
}

.card-row-view {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 2fr) auto;
  gap: 1rem;
  align-items: center;
}

.card-row-word {
  font-weight: 600;
  overflow-wrap: anywhere;
}

.card-row-definition {
  color: var(--dk-muted);
  overflow-wrap: anywhere;
}

.card-row-actions {
  display: flex;
}

.card-row-actions .btn-link {
  color: var(--dk-muted);
  text-decoration: none;
}

.card-row-actions .btn-link:hover {
  color: var(--dk-text);
}

@media (max-width: 575.98px) {
  .card-row-view {
    grid-template-columns: 1fr auto;
  }

  .card-row-definition {
    grid-column: 1 / -1;
    grid-row: 2;
  }
}

/* Study mode */
.study {
  max-width: 600px;
  margin: 0 auto;
}

.study-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: .5rem;
}

.study-progress {
  height: 4px;
  margin-bottom: 2rem;
  border-radius: 999px;
  background: var(--dk-border);
  overflow: hidden;
}

.study-progress-bar {
  width: 0;
  height: 100%;
  background: var(--dk-accent);
  transition: width .3s;
}

/* Stack: the cards waiting underneath peek out below the current one */
.study-stack {
  position: relative;
  isolation: isolate;
  padding-bottom: 24px;
}

.study-stack::before,
.study-stack::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  bottom: 24px;
  transform-origin: bottom center;
  z-index: -1;
  background: var(--dk-surface);
  border: 1px solid var(--dk-border-strong);
  box-shadow: var(--dk-shadow);
  border-radius: 18px;
  transition: opacity .25s;
}

.study-stack::before {
  transform: translateY(12px) scale(.95);
}

.study-stack::after {
  z-index: -2;
  transform: translateY(24px) scale(.9);
  opacity: .6;
}

.study-stack[data-remaining="1"]::after,
.study-stack[data-remaining="0"]::after,
.study-stack[data-remaining="0"]::before {
  opacity: 0;
}

.study-card {
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: center;
  min-height: 300px;
  padding: 2.5rem 2rem 3rem;
  background: var(--dk-surface);
  border: 1px solid var(--dk-border);
  border-left: 4px solid var(--dk-accent);
  border-radius: 18px;
  box-shadow: var(--dk-shadow-lg);
  color: var(--dk-text);
  cursor: pointer;
  outline: none;
  transition: transform .32s cubic-bezier(.4, 0, .2, 1), opacity .32s, border-color .2s, box-shadow .2s;
}

.study-card:focus-visible {
  box-shadow: 0 0 0 3px var(--dk-accent-ring), var(--dk-shadow-lg);
}

.study-card.is-revealed {
  cursor: default;
}

/* Enter from the stack, leave sideways depending on the grade */
.study-card.enter {
  transform: translateY(12px) scale(.96);
  opacity: 0;
  transition: none;
}

.study-card.exit-left {
  transform: translateX(-110%) rotate(-5deg);
  opacity: 0;
  border-color: #f59e0b;
}

.study-card.exit-right {
  transform: translateX(110%) rotate(5deg);
  opacity: 0;
  border-color: #22c55e;
}

.study-word {
  font-size: clamp(1.6rem, 5vw, 2.4rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  overflow-wrap: anywhere;
  transition: font-size .3s;
}

.study-card.is-revealed .study-word {
  font-size: clamp(1.3rem, 4vw, 1.75rem);
}

/* Answer unfolds underneath the word */
.study-answer {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows .35s cubic-bezier(.4, 0, .2, 1);
}

.study-card.is-revealed .study-answer {
  grid-template-rows: 1fr;
}

.study-answer-inner {
  overflow: hidden;
}

.study-divider {
  display: block;
  width: 0;
  height: 2px;
  margin: 1.25rem 0 1rem;
  background: var(--dk-accent);
  border-radius: 2px;
  transition: width .4s .1s cubic-bezier(.4, 0, .2, 1);
}

.study-card.is-revealed .study-divider {
  width: 48px;
}

.study-definition {
  display: block;
  color: var(--dk-text-2);
  font-size: clamp(1.05rem, 3vw, 1.3rem);
  line-height: 1.5;
  overflow-wrap: anywhere;
  opacity: 0;
  transform: translateY(8px);
  transition: opacity .3s .15s, transform .3s .15s;
}

.study-card.is-revealed .study-definition {
  opacity: 1;
  transform: none;
}

.study-hint {
  position: absolute;
  left: 2rem;
  bottom: 1.25rem;
  color: var(--dk-faint);
  font-size: .8rem;
  transition: opacity .2s;
}

.study-card.is-revealed .study-hint {
  opacity: 0;
}

.study-actions {
  display: grid;
  gap: .75rem;
  margin-top: 1.25rem;
}

.study-actions-grade {
  grid-template-columns: 1fr 1fr;
}

.study-actions[hidden] {
  display: none;
}

.btn-again {
  --bs-btn-hover-border-color: #f59e0b;
  --bs-btn-hover-bg: #fffbeb;
}

.btn-know {
  --bs-btn-hover-border-color: #22c55e;
  --bs-btn-hover-bg: #f0fdf4;
}

.study-actions kbd {
  margin-left: .35rem;
  padding: .1rem .4rem;
  font-size: .7rem;
  background: rgba(0, 0, 0, .08);
  color: inherit;
  border-radius: 4px;
}

.btn-dark kbd {
  background: rgba(255, 255, 255, .18);
}

.study-summary {
  padding: 2.5rem 1.5rem;
  text-align: center;
}

@media (prefers-reduced-motion: reduce) {
  .study-card,
  .study-answer,
  .study-divider,
  .study-definition {
    transition: none;
  }
}

/* About */
.about-intro .hero-title {
  max-width: 18ch;
}

.about-intro {
  padding-block: 1rem 2.5rem;
}

.feature {
  height: 100%;
  padding: 1.5rem;
  background: var(--dk-surface);
  border: 1px solid var(--dk-border);
  border-radius: var(--dk-radius);
  box-shadow: var(--dk-shadow);
}

.feature-icon {
  display: inline-grid;
  place-items: center;
  width: 40px;
  height: 40px;
  margin-bottom: 1rem;
  border-radius: 10px;
  background: var(--dk-subtle);
  font-size: 1.25rem;
}

.feature-title,
.step-title {
  font-size: 1.05rem;
  margin-bottom: .35rem;
}

.feature-text,
.step-text {
  margin: 0;
  color: var(--dk-muted);
}

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

.step {
  display: flex;
  gap: 1rem;
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--dk-border);
}

.step:last-child {
  border-bottom: 0;
}

.step-number {
  flex-shrink: 0;
  display: inline-grid;
  place-items: center;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--dk-accent);
  color: #fff;
  font-size: .9rem;
  font-weight: 600;
}

/* ---------- Colour accents ---------- */

/* Soft tones used to tell decks and features apart */
.tone-0 { --tone: #6366f1; --tone-soft: #eef2ff; }
.tone-1 { --tone: #10b981; --tone-soft: #d1fae5; }
.tone-2 { --tone: #f59e0b; --tone-soft: #fef3c7; }
.tone-3 { --tone: #0ea5e9; --tone-soft: #e0f2fe; }
.tone-4 { --tone: #f43f5e; --tone-soft: #ffe4e6; }
.tone-5 { --tone: #14b8a6; --tone-soft: #ccfbf1; }

.navbar .nav-link.active {
  color: var(--dk-accent);
}

.user-avatar {
  background: var(--dk-accent-soft);
  border-color: transparent;
  color: var(--dk-accent);
}

.eyebrow {
  background: var(--dk-accent-soft);
  border-color: transparent;
  color: var(--dk-accent);
}

.hero {
  border-color: #e0e7ff;
}

/* Home demo cards */
.flashcard {
  border-top: 3px solid var(--tone);
}

/* Deck tiles */
.deck-tile {
  padding-top: 1rem;
}

.deck-badge {
  display: inline-grid;
  place-items: center;
  width: 36px;
  height: 36px;
  margin-bottom: .5rem;
  border-radius: 10px;
  background: var(--tone-soft);
  color: var(--tone);
  font-weight: 700;
}

.deck-tile:hover {
  border-color: var(--tone);
}

.deck-dot {
  display: inline-block;
  width: 12px;
  height: 12px;
  margin-right: .5rem;
  border-radius: 50%;
  background: var(--tone);
  vertical-align: middle;
}

/* Study mode follows the deck's tone */
.study .study-progress-bar,
.study .study-divider {
  background: var(--tone);
}

.study .study-card {
  border-left-color: var(--tone);
}

/* About */
.feature-icon {
  background: var(--tone-soft);
}

.step-number {
  background: var(--dk-accent-soft);
  color: var(--dk-accent);
}

.cta {
  background: linear-gradient(180deg, #ffffff 0%, var(--dk-accent-soft) 100%);
  border-color: #e0e7ff;
}

.study .study-card.exit-left {
  border-color: #f59e0b;
}

.study .study-card.exit-right {
  border-color: #22c55e;
}

/* ---------- Pricing ---------- */
.pricing-intro {
  padding-block: 1rem 2.5rem;
}

.billing-toggle {
  display: inline-flex;
  gap: .25rem;
  padding: .25rem;
  background: var(--dk-surface);
  border: 1px solid var(--dk-border);
  border-radius: 999px;
}

.billing-option {
  padding: .45rem 1.1rem;
  border: 0;
  border-radius: 999px;
  background: transparent;
  color: var(--dk-muted);
  font-size: .9rem;
  font-weight: 500;
  transition: background-color .15s, color .15s;
}

.billing-option:hover {
  color: var(--dk-text);
}

.billing-option.is-active {
  background: var(--dk-accent);
  color: #fff;
}

.billing-save {
  margin-left: .25rem;
  padding: .1rem .4rem;
  border-radius: 999px;
  background: #d1fae5;
  color: #047857;
  font-size: .7rem;
  font-weight: 600;
}

.plans {
  max-width: 780px;
  margin-inline: auto;
}

.plan {
  position: relative;
  height: 100%;
  display: flex;
  flex-direction: column;
  padding: 1.75rem;
  background: var(--dk-surface);
  border: 1px solid var(--dk-border);
  border-top: 3px solid var(--tone);
  border-radius: 16px;
  box-shadow: var(--dk-shadow);
}

.plan-featured {
  border-color: var(--dk-accent);
  border-top-width: 3px;
  box-shadow: 0 0 0 1px var(--dk-accent), var(--dk-shadow-lg);
}

@media (min-width: 992px) {
  .plan-featured {
    transform: translateY(-8px);
  }
}

.plan-badge {
  position: absolute;
  top: -12px;
  right: 1.5rem;
  padding: .2rem .65rem;
  border-radius: 999px;
  background: var(--dk-accent);
  color: #fff;
  font-size: .75rem;
  font-weight: 600;
}

.plan-name {
  font-size: 1.15rem;
  margin-bottom: .25rem;
}

.plan-description {
  color: var(--dk-muted);
  font-size: .95rem;
  margin-bottom: 1.25rem;
}

.plan-price {
  display: flex;
  align-items: baseline;
  gap: .4rem;
  margin-bottom: 1.25rem;
}

.plan-amount {
  font-size: 2.25rem;
  font-weight: 700;
  letter-spacing: -0.03em;
}

.plan-period {
  color: var(--dk-muted);
  font-size: .9rem;
}

.plan .btn:disabled {
  opacity: .55;
}

.plan-features {
  list-style: none;
  margin: 1.5rem 0 0;
  padding: 1.25rem 0 0;
  border-top: 1px solid var(--dk-border);
  display: grid;
  gap: .6rem;
}

.plan-features li {
  position: relative;
  padding-left: 1.6rem;
  color: var(--dk-text-2);
  font-size: .95rem;
}

.plan-features li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .2rem;
  width: 1rem;
  height: 1rem;
  border-radius: 50%;
  background: var(--tone-soft);
}

.plan-features li::after {
  content: "";
  position: absolute;
  left: .33rem;
  top: .38rem;
  width: .35rem;
  height: .55rem;
  border: solid var(--tone);
  border-width: 0 2px 2px 0;
  transform: rotate(45deg);
}

.faq {
  max-width: 720px;
  margin: 0 auto;
  padding: 0;
}

.faq-item {
  border-bottom: 1px solid var(--dk-border);
}

.faq-item:last-child {
  border-bottom: 0;
}

.faq-item summary {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: 1rem 1.25rem;
  font-weight: 500;
  cursor: pointer;
  list-style: none;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  content: "+";
  color: var(--dk-accent);
  font-size: 1.25rem;
  line-height: 1;
  transition: transform .2s;
}

.faq-item[open] summary::after {
  transform: rotate(45deg);
}

.faq-item p {
  margin: 0;
  padding: 0 1.25rem 1rem;
  color: var(--dk-muted);
}

/* ---------- Home: How it works (interactive demo) ---------- */
.how-it-works .eyebrow {
  margin-bottom: .75rem;
}

.how-steps {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: .5rem;
}

.how-step {
  display: flex;
  gap: .9rem;
  padding: .9rem 1rem;
  border: 1px solid transparent;
  border-radius: var(--dk-radius);
  transition: background-color .25s, border-color .25s, box-shadow .25s;
}

.how-step.is-active {
  background: var(--dk-surface);
  border-color: var(--dk-border);
  box-shadow: var(--dk-shadow);
}

.how-step-number {
  flex-shrink: 0;
  display: inline-grid;
  place-items: center;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: var(--dk-subtle);
  color: var(--dk-muted);
  font-size: .85rem;
  font-weight: 600;
  transition: background-color .25s, color .25s;
}

.how-step.is-active .how-step-number {
  background: var(--dk-accent);
  color: #fff;
}

.how-step-title {
  font-size: 1rem;
  margin: .2rem 0 .15rem;
}

.how-step-text {
  margin: 0;
  color: var(--dk-muted);
  font-size: .9rem;
}

.demo {
  max-width: none;
}

.demo .study-card {
  min-height: 240px;
}

.demo-score {
  color: var(--dk-muted);
}

.demo-score-know {
  color: #059669;
  font-weight: 600;
}

.demo-score-again {
  color: #d97706;
  font-weight: 600;
}

/* ---------- Vocabulary tests (Pro) ---------- */
.plan-badge-inline {
  display: inline-block;
  padding: .1rem .5rem;
  border-radius: 999px;
  background: var(--dk-accent-soft);
  color: var(--dk-accent);
  font-size: .7rem;
  font-weight: 700;
  letter-spacing: .02em;
  vertical-align: middle;
}

.quiz-locked {
  max-width: 560px;
  margin: 0 auto;
  padding: 2.5rem 1.5rem;
  text-align: center;
}

.quiz-lock-icon {
  font-size: 2.25rem;
}

.quiz-setup {
  padding: 1.75rem;
}

.quiz-field {
  margin-bottom: 1.5rem;
}

.quiz-label {
  display: block;
  margin-bottom: .5rem;
  color: var(--dk-muted);
  font-size: .75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .06em;
}

.quiz-segment {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: .5rem;
}

@media (max-width: 575.98px) {
  .quiz-segment {
    grid-template-columns: 1fr;
  }
}

.quiz-option {
  display: flex;
  flex-direction: column;
  gap: .2rem;
  padding: .85rem 1rem;
  text-align: left;
  background: var(--dk-surface);
  border: 1px solid var(--dk-border);
  border-radius: 10px;
  color: var(--dk-text);
  transition: border-color .15s, background-color .15s, box-shadow .15s;
}

.quiz-option span {
  color: var(--dk-muted);
  font-size: .85rem;
}

.quiz-option:hover:not(:disabled) {
  border-color: var(--dk-border-strong);
}

.quiz-option.is-active {
  border-color: var(--tone);
  background: var(--tone-soft);
  box-shadow: 0 0 0 1px var(--tone);
}

.quiz-option:disabled {
  opacity: .5;
  cursor: not-allowed;
}

.quiz-note {
  margin: .5rem 0 0;
  color: var(--dk-muted);
  font-size: .85rem;
}

.quiz-counts {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
}

.quiz-count {
  min-width: 56px;
  padding: .45rem .9rem;
  background: var(--dk-surface);
  border: 1px solid var(--dk-border);
  border-radius: 999px;
  color: var(--dk-text);
  font-weight: 500;
}

.quiz-count.is-active {
  background: var(--tone);
  border-color: var(--tone);
  color: #fff;
}

.quiz-card {
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: .5rem;
  min-height: 170px;
  padding: 2rem;
  margin-bottom: 1.25rem;
  background: var(--dk-surface);
  border: 1px solid var(--dk-border);
  border-left: 4px solid var(--tone);
  border-radius: 18px;
  box-shadow: var(--dk-shadow-lg);
}

.quiz-prompt-label {
  color: var(--dk-muted);
  font-size: .75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .06em;
}

.quiz-prompt {
  font-size: clamp(1.3rem, 4vw, 1.9rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  overflow-wrap: anywhere;
}

.quiz-choices {
  display: grid;
  gap: .6rem;
}

.quiz-choice {
  display: flex;
  align-items: center;
  gap: .75rem;
  width: 100%;
  padding: .85rem 1rem;
  text-align: left;
  background: var(--dk-surface);
  border: 1px solid var(--dk-border);
  border-radius: 12px;
  color: var(--dk-text);
  transition: border-color .15s, background-color .15s;
}

.quiz-choice:hover:not(:disabled) {
  border-color: var(--tone);
  background: var(--tone-soft);
}

.quiz-choice kbd {
  flex-shrink: 0;
  padding: .1rem .45rem;
  background: var(--dk-subtle);
  color: var(--dk-muted);
  border-radius: 6px;
  font-size: .75rem;
}

.quiz-choice span {
  overflow-wrap: anywhere;
}

.quiz-choice:disabled {
  cursor: default;
}

.quiz-choice.is-correct {
  border-color: #22c55e;
  background: #f0fdf4;
}

.quiz-choice.is-wrong {
  border-color: #f43f5e;
  background: #fff1f2;
}

.quiz-typing {
  display: flex;
  gap: .5rem;
}

.quiz-feedback {
  margin-top: 1rem;
  padding: .8rem 1rem;
  border-radius: 10px;
  font-weight: 500;
  overflow-wrap: anywhere;
}

.quiz-feedback.is-correct {
  background: #f0fdf4;
  color: #15803d;
}

.quiz-feedback.is-wrong {
  background: #fff1f2;
  color: #be123c;
}

.quiz-results {
  padding: 2.5rem 1.5rem;
  text-align: center;
}

.quiz-score-ring {
  --p: 0;
  display: grid;
  place-items: center;
  width: 110px;
  height: 110px;
  margin: 0 auto 1rem;
  border-radius: 50%;
  background:
    radial-gradient(closest-side, var(--dk-surface) 78%, transparent 80%),
    conic-gradient(var(--tone) calc(var(--p) * 1%), var(--dk-border) 0);
  font-size: 1.6rem;
  font-weight: 700;
}

.quiz-mistakes {
  list-style: none;
  margin: 0;
  padding: 0;
  text-align: left;
  border: 1px solid var(--dk-border);
  border-radius: 12px;
}

.quiz-mistakes li {
  display: grid;
  gap: .1rem;
  padding: .75rem 1rem;
  border-bottom: 1px solid var(--dk-border);
}

.quiz-mistakes li:last-child {
  border-bottom: 0;
}

.quiz-mistakes span {
  color: var(--dk-text-2);
}

.quiz-mistakes small {
  color: #be123c;
}