:root {
  color-scheme: dark;
  --bg: #090d18;
  --bg-deep: #050711;
  --surface: #11182a;
  --surface-raised: #182238;
  --surface-soft: #202d47;
  --text: #ecf4ff;
  --muted: #9aabc3;
  --faint: #63738c;
  --line: #2d3c58;
  --accent: #64d5ff;
  --accent-strong: #20ade2;
  --accent-ink: #062334;
  --success: #75df9a;
  --danger: #ff8c9c;
  --shadow: 0 18px 50px rgba(0, 0, 0, 0.28);
  --radius: 18px;
  --font: ui-rounded, "Avenir Next", "Segoe UI", system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
}

body.theme-light {
  color-scheme: light;
  --bg: #edf4fb;
  --bg-deep: #dcebf7;
  --surface: #ffffff;
  --surface-raised: #f8fbff;
  --surface-soft: #e9f4fc;
  --text: #15233a;
  --muted: #526783;
  --faint: #71839b;
  --line: #c9d9e8;
  --accent: #087faf;
  --accent-strong: #006d9c;
  --accent-ink: #ffffff;
  --success: #197b42;
  --danger: #bd3852;
  --shadow: 0 18px 45px rgba(38, 74, 111, 0.14);
}

* {
  box-sizing: border-box;
}

body {
  min-width: 320px;
  min-height: 100vh;
  margin: 0;
  background:
    radial-gradient(circle at 8% 0%, rgba(59, 157, 220, 0.14), transparent 30rem),
    radial-gradient(circle at 95% 18%, rgba(89, 79, 196, 0.14), transparent 28rem),
    var(--bg);
  color: var(--text);
  font-family: var(--font);
  transition: background-color 180ms ease, color 180ms ease;
}

button,
input {
  font: inherit;
}

button {
  -webkit-tap-highlight-color: transparent;
}

button:focus-visible,
input:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 3px;
}

.hidden {
  display: none !important;
}

#app {
  width: min(100%, 1120px);
  min-height: 100vh;
  margin: 0 auto;
  padding: 0 16px;
}

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 90px;
  gap: 20px;
  padding: 18px 0;
}

.brand h1,
.welcome-card h2,
.section-heading h2,
.review-heading h2,
.modal-card h2 {
  margin: 0;
  letter-spacing: -0.04em;
}

.brand h1 {
  font-size: clamp(1.5rem, 5vw, 2rem);
  line-height: 1;
}

.eyebrow {
  margin: 0 0 5px;
  color: var(--accent);
  font-size: 0.7rem;
  font-weight: 800;
  letter-spacing: 0.13em;
  text-transform: uppercase;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.button {
  min-height: 44px;
  border: 1px solid transparent;
  border-radius: 12px;
  padding: 10px 14px;
  cursor: pointer;
  font-weight: 800;
  line-height: 1.1;
  transition: transform 140ms ease, background 140ms ease, border-color 140ms ease, opacity 140ms ease;
}

.button:hover:not(:disabled) {
  transform: translateY(-1px);
}

.button:active:not(:disabled) {
  transform: translateY(1px);
}

.button:disabled,
.quiz-option:disabled,
.word-token:disabled,
.match-target:disabled {
  cursor: not-allowed;
  opacity: 0.64;
}

.button-primary {
  border-color: var(--accent);
  background: var(--accent);
  color: var(--accent-ink);
}

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

.button-secondary {
  border-color: var(--line);
  background: var(--surface-raised);
  color: var(--text);
}

.button-secondary:hover:not(:disabled),
.button-quiet:hover:not(:disabled) {
  border-color: var(--accent);
  background: var(--surface-soft);
}

.button-quiet {
  border-color: var(--line);
  background: transparent;
  color: var(--muted);
}

.count-pill {
  display: inline-grid;
  min-width: 22px;
  min-height: 22px;
  place-items: center;
  margin-left: 5px;
  padding: 1px 6px;
  border-radius: 999px;
  background: var(--surface-soft);
  color: var(--muted);
  font-size: 0.75rem;
}

.count-pill.has-words {
  background: var(--accent);
  color: var(--accent-ink);
}

main {
  padding-bottom: 28px;
}

.welcome-card {
  position: relative;
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
  overflow: hidden;
  padding: clamp(22px, 5vw, 40px);
  border: 1px solid var(--line);
  border-radius: 24px;
  background:
    linear-gradient(115deg, rgba(61, 198, 255, 0.11), transparent 52%),
    var(--surface);
  box-shadow: var(--shadow);
}

.welcome-card::after {
  position: absolute;
  right: -56px;
  bottom: -62px;
  width: 240px;
  height: 240px;
  content: "";
  background-image: url("https://assets.popchat.com/assets/kenney/puzzle/PNG/Particles%20blue/particleBlue_2.png");
  background-repeat: no-repeat;
  background-size: contain;
  opacity: 0.22;
  pointer-events: none;
}

.welcome-copy {
  position: relative;
  z-index: 1;
  max-width: 630px;
}

.welcome-card h2 {
  max-width: 520px;
  font-size: clamp(1.8rem, 7vw, 3rem);
  line-height: 0.98;
}

.welcome-copy > p:last-child {
  max-width: 610px;
  margin: 14px 0 0;
  color: var(--muted);
  line-height: 1.6;
}

.streak-card {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  width: fit-content;
  min-height: 72px;
  gap: 12px;
  padding: 12px 16px 12px 12px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: rgba(5, 12, 27, 0.28);
  backdrop-filter: blur(8px);
}

.theme-light .streak-card {
  background: rgba(255, 255, 255, 0.64);
}

.coin-mark {
  display: block;
  width: 42px;
  height: 42px;
  flex: 0 0 42px;
  background: url("https://assets.popchat.com/assets/kenney/puzzle/PNG/Coins/coin_01.png") center / contain no-repeat;
  filter: drop-shadow(0 5px 7px rgba(0, 0, 0, 0.25));
}

.streak-card strong,
.streak-card span:not(.coin-mark) {
  display: block;
}

.streak-card strong {
  font-size: 1.1rem;
}

.streak-card span:not(.coin-mark) {
  margin-top: 2px;
  color: var(--muted);
  font-size: 0.82rem;
}

.batch-nav {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
  margin: 20px 0;
}

.batch-button {
  display: grid;
  min-height: 88px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 15px;
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  text-align: left;
  transition: border-color 140ms ease, background 140ms ease, transform 140ms ease;
}

.batch-button:hover {
  border-color: var(--accent);
  transform: translateY(-1px);
}

.batch-button.active {
  border-color: var(--accent);
  background: linear-gradient(125deg, rgba(72, 205, 255, 0.15), var(--surface));
  box-shadow: inset 0 0 0 1px rgba(94, 212, 255, 0.15);
}

.batch-button-label,
.batch-button small {
  color: var(--muted);
  font-size: 0.76rem;
}

.batch-button-label {
  color: var(--accent);
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.batch-button strong {
  margin: 3px 0;
  font-size: 1rem;
}

.learn-view,
.review-view {
  padding: clamp(20px, 4vw, 34px);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow);
}

.section-heading,
.review-heading,
.quiz-heading {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 14px;
}

.section-heading h2,
.review-heading h2 {
  font-size: clamp(1.45rem, 5vw, 2rem);
}

.progress-text {
  margin: 7px 0 0;
  color: var(--muted);
  font-size: 0.84rem;
  font-weight: 700;
  white-space: nowrap;
}

.progress-track {
  height: 8px;
  margin: 20px 0 26px;
  overflow: hidden;
  border-radius: 99px;
  background: var(--surface-soft);
}

.progress-fill {
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--accent-strong), var(--accent));
  transition: width 260ms ease;
}

.word-card {
  min-height: 310px;
  padding: clamp(24px, 7vw, 48px);
  border: 1px solid var(--line);
  border-radius: 20px;
  background:
    linear-gradient(145deg, rgba(66, 191, 244, 0.08), transparent 54%),
    var(--surface-raised);
}

.card-label,
.word-batch {
  margin: 0;
  color: var(--accent);
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.word-card h3 {
  margin: 12px 0 2px;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(2.2rem, 11vw, 4.5rem);
  font-weight: 700;
  letter-spacing: -0.05em;
  line-height: 0.98;
}

.pronunciation {
  margin: 0;
  color: var(--muted);
  font-size: 0.93rem;
  font-style: italic;
}

.definition-area {
  margin-top: 28px;
}

.definition-area.concealed {
  display: none;
}

.definition {
  max-width: 690px;
  margin: 0;
  font-size: clamp(1.08rem, 3vw, 1.3rem);
  font-weight: 700;
  line-height: 1.5;
}

.example {
  max-width: 680px;
  margin: 16px 0 0;
  color: var(--muted);
  font-size: 0.97rem;
  font-style: italic;
  line-height: 1.55;
}

.reveal-hint {
  margin: 36px 0 0;
  color: var(--faint);
  font-size: 0.9rem;
}

.study-controls {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.3fr);
  gap: 10px;
  margin-top: 16px;
}

.study-controls .button:last-child {
  grid-column: 2;
}

.study-note {
  min-height: 1.5em;
  margin: 15px 0 0;
  color: var(--muted);
  font-size: 0.9rem;
  text-align: center;
}

.search-field {
  display: grid;
  gap: 7px;
  margin: 24px 0 18px;
  color: var(--muted);
  font-size: 0.84rem;
  font-weight: 800;
}

.search-field input,
.spelling-form input {
  width: 100%;
  min-height: 48px;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 10px 13px;
  background: var(--surface-raised);
  color: var(--text);
}

.search-field input::placeholder,
.spelling-form input::placeholder {
  color: var(--faint);
}

.empty-state,
.no-match {
  padding: 28px;
  border: 1px dashed var(--line);
  border-radius: 16px;
  background: var(--surface-raised);
  color: var(--muted);
  text-align: center;
}

.empty-state h3 {
  margin: 0;
  color: var(--text);
}

.empty-state p {
  max-width: 470px;
  margin: 9px auto 0;
  line-height: 1.6;
}

.word-list {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
}

.review-word {
  padding: 19px;
  border: 1px solid var(--line);
  border-radius: 15px;
  background: var(--surface-raised);
}

.review-word h3 {
  margin: 7px 0 1px;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.65rem;
  letter-spacing: -0.03em;
}

.review-definition {
  margin: 15px 0 0;
  font-weight: 700;
  line-height: 1.5;
}

.review-example {
  margin: 10px 0 0;
  color: var(--muted);
  font-size: 0.92rem;
  font-style: italic;
  line-height: 1.5;
}

.quiz-panel {
  margin-top: 24px;
  padding: clamp(20px, 5vw, 30px);
  border: 1px solid rgba(100, 213, 255, 0.45);
  border-radius: 18px;
  background: linear-gradient(145deg, rgba(54, 193, 245, 0.12), var(--surface-raised));
}

.quiz-heading h3 {
  margin: 0;
  font-size: 1.2rem;
}

.quiz-mode-wrap {
  margin-top: 20px;
}

.mode-label,
.quiz-question-label {
  margin: 0 0 8px;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.mode-help {
  margin: -1px 0 12px;
  color: var(--faint);
  font-size: 0.87rem;
  line-height: 1.45;
}

.quiz-modes {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.quiz-mode {
  position: relative;
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 8px 14px 8px 35px;
  background: var(--surface);
  color: var(--muted);
  cursor: pointer;
  font-size: 0.86rem;
  font-weight: 800;
}

.quiz-mode::before {
  position: absolute;
  top: 50%;
  left: 13px;
  width: 14px;
  height: 14px;
  border: 2px solid currentColor;
  border-radius: 4px;
  content: "";
  transform: translateY(-50%);
}

.quiz-mode.active {
  border-color: var(--accent);
  background: var(--accent);
  color: var(--accent-ink);
}

.quiz-mode.active::after {
  position: absolute;
  top: 50%;
  left: 17px;
  width: 7px;
  height: 4px;
  border-bottom: 2px solid var(--accent-ink);
  border-left: 2px solid var(--accent-ink);
  content: "";
  transform: translateY(-65%) rotate(-45deg);
}

.quiz-mode:hover {
  border-color: var(--accent);
}

.quiz-content {
  margin-top: 22px;
}

.quiz-style-label {
  display: inline-block;
  margin: 0 0 9px;
  padding: 5px 9px;
  border: 1px solid color-mix(in srgb, var(--accent) 45%, var(--line));
  border-radius: 999px;
  background: color-mix(in srgb, var(--accent) 10%, transparent);
  color: var(--accent);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.quiz-definition {
  margin: 0 0 20px;
  font-size: 1.08rem;
  font-weight: 700;
  line-height: 1.5;
}

.quiz-options {
  display: grid;
  grid-template-columns: 1fr;
  gap: 9px;
}

.quiz-option {
  min-height: 46px;
  border: 1px solid var(--line);
  border-radius: 11px;
  padding: 10px 12px;
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  font-weight: 800;
  text-align: left;
}

.quiz-option:hover:not(:disabled) {
  border-color: var(--accent);
  background: var(--surface-soft);
}

.quiz-option.correct,
.answer-correct {
  border-color: var(--success);
  background: color-mix(in srgb, var(--success) 17%, var(--surface));
}

.quiz-option.incorrect,
.answer-incorrect {
  border-color: var(--danger);
  background: color-mix(in srgb, var(--danger) 13%, var(--surface));
}

.spelling-form {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
}

.drag-instruction {
  margin: -5px 0 16px;
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.45;
}

.matching-board {
  display: grid;
  gap: 14px;
}

.word-bank {
  display: flex;
  flex-wrap: wrap;
  gap: 9px;
  padding: 12px;
  border: 1px dashed var(--line);
  border-radius: 14px;
  background: rgba(5, 12, 27, 0.14);
}

.word-token {
  min-height: 44px;
  border: 1px solid var(--accent);
  border-radius: 10px;
  padding: 8px 12px;
  background: var(--surface);
  color: var(--text);
  cursor: grab;
  font-weight: 800;
}

.word-token.selected {
  background: var(--accent);
  color: var(--accent-ink);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 25%, transparent);
}

.match-targets {
  display: grid;
  gap: 10px;
}

.match-target {
  display: flex;
  align-items: flex-start;
  min-height: 82px;
  gap: 10px;
  border: 1px dashed var(--line);
  border-radius: 13px;
  padding: 12px;
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  line-height: 1.45;
  text-align: left;
}

.match-target.drag-over {
  border-color: var(--accent);
  background: var(--surface-soft);
}

.match-number {
  display: inline-grid;
  width: 24px;
  height: 24px;
  flex: 0 0 24px;
  place-items: center;
  border-radius: 999px;
  background: var(--surface-soft);
  color: var(--accent);
  font-size: 0.76rem;
  font-weight: 800;
}

.placed-word {
  display: block;
  flex: 0 0 auto;
  color: var(--accent);
}

.placed-word.correction {
  color: var(--success);
}

.match-target.match-correct {
  border-color: var(--success);
}

.match-target.match-incorrect {
  border-color: var(--danger);
}

.quiz-feedback {
  min-height: 1.5em;
  margin: 15px 0 0;
  color: var(--muted);
  font-size: 0.92rem;
  font-weight: 700;
  line-height: 1.5;
}

footer {
  padding: 18px 0 28px;
  color: var(--faint);
  font-size: 0.82rem;
  text-align: center;
}

footer p {
  margin: 0;
}

.modal {
  position: fixed;
  z-index: 20;
  inset: 0;
  display: grid;
  place-items: center;
  padding: 18px;
  background: rgba(2, 6, 16, 0.76);
  backdrop-filter: blur(7px);
}

.modal-card {
  width: min(100%, 450px);
  padding: 30px;
  border: 1px solid var(--accent);
  border-radius: 22px;
  background:
    linear-gradient(145deg, rgba(74, 206, 255, 0.13), transparent 60%),
    var(--surface);
  box-shadow: 0 26px 70px rgba(0, 0, 0, 0.45);
  text-align: center;
}

.modal-card h2 {
  margin-top: 7px;
  font-size: clamp(1.6rem, 7vw, 2.25rem);
  line-height: 1.02;
}

.modal-card > p:not(.eyebrow) {
  margin: 16px 0 0;
  color: var(--muted);
  line-height: 1.55;
}

.modal-actions {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
  margin-top: 25px;
}

@media (min-width: 640px) {
  #app {
    padding: 0 24px;
  }

  .welcome-card {
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: center;
  }

  .batch-nav {
    grid-template-columns: repeat(3, 1fr);
  }

  .study-controls {
    display: flex;
    justify-content: center;
  }

  .study-controls .button,
  .study-controls .button:last-child {
    grid-column: auto;
    min-width: 140px;
  }

  .word-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .quiz-options {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .spelling-form {
    grid-template-columns: minmax(0, 1fr) auto;
  }

  .matching-board {
    grid-template-columns: minmax(160px, 0.75fr) minmax(0, 1.6fr);
  }

  .word-bank {
    align-content: start;
  }

  .modal-actions {
    grid-template-columns: 1.3fr 1fr;
  }
}

@media (max-width: 470px) {
  .site-header {
    align-items: flex-start;
    flex-direction: column;
  }

  .header-actions {
    width: 100%;
  }

  .header-actions .button {
    flex: 1;
  }

  .section-heading,
  .review-heading,
  .quiz-heading {
    flex-direction: column;
  }

  .progress-text {
    margin-top: 0;
  }

  .review-heading .button,
  .quiz-heading .button {
    width: 100%;
  }

  .quiz-mode {
    flex: 1 1 calc(50% - 8px);
  }
}