:root {
  color-scheme: light;
  --bg: #f5f5f7;
  --surface: #ffffff;
  --surface-muted: #eeeeef;
  --surface-hover: #e8e8ea;
  --text: #1d1d1f;
  --text-secondary: #6e6e73;
  --text-tertiary: #8e8e93;
  --separator: rgba(60, 60, 67, 0.18);
  --separator-soft: rgba(60, 60, 67, 0.10);
  --accent: #2c2c2e;
  --accent-hover: #000000;
  --success: #2f6b4f;
  --success-bg: #edf5f0;
  --error: #9a3535;
  --error-bg: #f8eeee;
  --focus: rgba(0, 122, 255, 0.24);
  --radius-small: 10px;
  --radius-medium: 16px;
  --radius-large: 24px;
  --content: 1180px;
  --shadow-float: 0 10px 30px rgba(0, 0, 0, 0.06);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "SF Pro Display", "Segoe UI", Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.48;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

button,
input,
select,
textarea {
  font: inherit;
}

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

button:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 64px;
  padding: 10px max(24px, calc((100vw - var(--content)) / 2));
  background: rgba(245, 245, 247, 0.82);
  border-bottom: 1px solid var(--separator-soft);
  backdrop-filter: saturate(180%) blur(24px);
  -webkit-backdrop-filter: saturate(180%) blur(24px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  color: inherit;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 36px;
  height: 36px;
  place-items: center;
  border-radius: 10px;
  background: var(--text);
  color: #fff;
  font-size: 17px;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.brand strong,
.brand small {
  display: block;
}

.brand strong {
  font-size: 15px;
  font-weight: 650;
  letter-spacing: -0.01em;
}

.brand small {
  color: var(--text-secondary);
  font-size: 12px;
}

.topnav {
  display: inline-flex;
  gap: 2px;
  padding: 3px;
  border-radius: 11px;
  background: rgba(118, 118, 128, 0.12);
}

.nav-btn,
.content-tab {
  min-height: 38px;
  border: 0;
  background: transparent;
  color: var(--text-secondary);
  font-weight: 600;
}

.nav-btn {
  min-width: 84px;
  padding: 8px 13px;
  border-radius: 8px;
  font-size: 14px;
}

.nav-btn.active {
  background: var(--surface);
  color: var(--text);
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.08);
}

.nav-btn:hover:not(.active) {
  color: var(--text);
}

.view {
  display: none;
}

.view.active {
  display: block;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.55fr) minmax(260px, 0.45fr);
  gap: clamp(44px, 7vw, 96px);
  align-items: end;
  max-width: var(--content);
  min-height: 490px;
  margin: 0 auto;
  padding: clamp(76px, 10vw, 132px) 24px 70px;
}

.hero-copy {
  max-width: 820px;
}

.eyebrow {
  display: inline-block;
  margin-bottom: 12px;
  color: var(--text-secondary);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1,
h2,
h3 {
  letter-spacing: -0.035em;
}

h1,
h2 {
  line-height: 1.06;
}

.hero h1 {
  max-width: 820px;
  margin-bottom: 22px;
  font-size: clamp(48px, 7vw, 82px);
  font-weight: 720;
}

.hero-copy > p {
  max-width: 690px;
  margin-bottom: 0;
  color: var(--text-secondary);
  font-size: clamp(18px, 2vw, 21px);
  line-height: 1.5;
}

.hero-actions,
.result-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 30px;
}

.primary-btn,
.secondary-btn {
  min-height: 44px;
  padding: 11px 18px;
  border-radius: 12px;
  font-weight: 650;
  letter-spacing: -0.01em;
  transition: background 150ms ease, transform 150ms ease, opacity 150ms ease;
}

.primary-btn {
  border: 1px solid var(--accent);
  background: var(--accent);
  color: #fff;
}

.primary-btn:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
}

.secondary-btn {
  border: 1px solid var(--separator);
  background: transparent;
  color: var(--text);
}

.secondary-btn:hover {
  background: rgba(118, 118, 128, 0.08);
}

.primary-btn.large {
  width: 100%;
  margin-top: 14px;
  padding: 14px 18px;
}

.secondary-btn.danger {
  color: var(--error);
}

.hero-card {
  padding: 0 0 5px 28px;
  border-left: 1px solid var(--separator);
  background: transparent;
}

.hero-card-label {
  margin-bottom: 3px;
  color: var(--text-secondary);
  font-size: 14px;
}

.hero-card > strong {
  display: block;
  margin-bottom: 16px;
  font-size: 44px;
  font-weight: 700;
  letter-spacing: -0.045em;
}

.progress-track {
  height: 6px;
  overflow: hidden;
  border-radius: 999px;
  background: rgba(118, 118, 128, 0.18);
}

.progress-track span {
  display: block;
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: var(--text);
  transition: width 280ms ease;
}

.progress-track.compact {
  height: 5px;
}

.hero-card #hero-progress-text {
  margin: 13px 0 0;
  color: var(--text-secondary);
  font-size: 14px;
}

.section-shell {
  max-width: var(--content);
  margin: 0 auto;
  padding: 70px 24px 100px;
}

#home-view .section-shell {
  border-top: 1px solid var(--separator-soft);
}

.section-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 42px;
  margin-bottom: 28px;
}

.section-heading h1,
.section-heading h2 {
  margin-bottom: 0;
  font-size: clamp(36px, 4.5vw, 56px);
  font-weight: 700;
}

.section-heading > p {
  max-width: 500px;
  margin-bottom: 4px;
  color: var(--text-secondary);
}

.unit-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  border-top: 1px solid var(--separator);
}

.unit-card {
  position: relative;
  display: grid;
  grid-template-columns: 54px minmax(0, 1fr) auto;
  gap: 16px;
  align-items: center;
  min-height: 126px;
  padding: 22px 18px 22px 0;
  border: 0;
  border-bottom: 1px solid var(--separator);
  background: transparent;
  color: inherit;
  text-align: left;
}

.unit-card:nth-child(odd) {
  padding-right: 32px;
  border-right: 1px solid var(--separator);
}

.unit-card:nth-child(even) {
  padding-left: 32px;
}

.unit-card:hover {
  background: rgba(255, 255, 255, 0.46);
}

.unit-number {
  display: grid;
  width: 44px;
  height: 44px;
  place-items: center;
  border-radius: 50%;
  background: var(--surface-muted);
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 700;
}

.unit-card h3 {
  margin-bottom: 5px;
  font-size: 19px;
  font-weight: 650;
}

.unit-card p {
  margin-bottom: 0;
  color: var(--text-secondary);
  font-size: 14px;
}

.unit-arrow {
  color: var(--text-tertiary);
  font-size: 22px;
}

.unit-badge {
  position: absolute;
  top: 14px;
  right: 18px;
  color: var(--text-tertiary);
  font-size: 11px;
  font-weight: 650;
}

.unit-layout {
  display: grid;
  grid-template-columns: 248px minmax(0, 1fr);
  min-height: calc(100vh - 65px);
}

.unit-sidebar {
  padding: 28px 18px;
  border-right: 1px solid var(--separator-soft);
  background: rgba(238, 238, 239, 0.52);
}

.back-link {
  min-height: 44px;
  margin-bottom: 14px;
  padding: 0 10px;
  border: 0;
  background: transparent;
  color: var(--text-secondary);
  font-weight: 600;
}

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

.side-unit-btn {
  width: 100%;
  min-height: 44px;
  margin-bottom: 3px;
  padding: 10px 12px;
  border: 0;
  border-radius: 10px;
  background: transparent;
  color: var(--text-secondary);
  text-align: left;
}

.side-unit-btn.active {
  background: var(--surface);
  color: var(--text);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
  font-weight: 600;
}

.side-unit-btn:hover:not(.active) {
  background: rgba(118, 118, 128, 0.08);
}

.unit-content {
  width: min(100%, 1020px);
  padding: 66px clamp(28px, 6vw, 84px) 100px;
}

.unit-title-row {
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: 34px;
}

.unit-title-row h1 {
  margin-bottom: 13px;
  font-size: clamp(42px, 5vw, 64px);
  font-weight: 710;
}

.unit-title-row p {
  max-width: 660px;
  color: var(--text-secondary);
  font-size: 17px;
}

.content-tabs {
  display: flex;
  gap: 3px;
  margin: 38px 0 34px;
  overflow-x: auto;
  border-bottom: 1px solid var(--separator);
  scrollbar-width: none;
}

.content-tabs::-webkit-scrollbar {
  display: none;
}

.content-tab {
  flex: 0 0 auto;
  padding: 11px 13px 12px;
  border-bottom: 2px solid transparent;
  font-size: 14px;
}

.content-tab.active {
  border-bottom-color: var(--text);
  color: var(--text);
}

.content-tab:hover:not(.active) {
  color: var(--text);
}

.tab-panel {
  min-height: 360px;
}

.vocab-table {
  width: 100%;
  border-collapse: collapse;
  background: transparent;
}

.vocab-table th,
.vocab-table td {
  padding: 15px 4px;
  border-bottom: 1px solid var(--separator-soft);
  text-align: left;
}

.vocab-table th {
  color: var(--text-tertiary);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.vocab-table td:first-child {
  width: 46%;
}

.vocab-table td strong {
  font-weight: 620;
}

.phrase-list {
  border-top: 1px solid var(--separator);
}

.phrase-item {
  padding: 18px 4px;
  border-bottom: 1px solid var(--separator-soft);
}

.phrase-item strong {
  display: block;
  margin-bottom: 4px;
  font-size: 17px;
  font-weight: 620;
}

.phrase-item span {
  color: var(--text-secondary);
}

.dialogue-box,
.reading-box,
.speaking-box {
  padding: 0;
  background: transparent;
}

.dialogue-line {
  display: grid;
  grid-template-columns: 100px 1fr;
  gap: 18px;
  margin: 0;
  padding: 16px 0;
  border-bottom: 1px solid var(--separator-soft);
}

.dialogue-line:first-child {
  border-top: 1px solid var(--separator);
}

.dialogue-line strong {
  font-weight: 650;
}

.reading-box p {
  max-width: 760px;
  font-size: 20px;
  line-height: 1.72;
}

.speaking-box h2 {
  max-width: 680px;
  font-size: clamp(30px, 4vw, 42px);
  font-weight: 680;
}

.speaking-box ul {
  max-width: 700px;
  margin: 22px 0 28px;
  padding-left: 24px;
}

.speaking-box li {
  padding: 6px 0;
}

.practice-shell {
  max-width: 920px;
}

.practice-setup,
.quiz-card,
.result-card {
  background: transparent;
}

.practice-setup label {
  display: grid;
  gap: 8px;
  margin-bottom: 28px;
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 600;
}

select,
.text-answer,
.reply-answer {
  width: 100%;
  border: 1px solid var(--separator);
  border-radius: 12px;
  background: var(--surface);
  color: var(--text);
  outline: none;
}

select {
  min-height: 48px;
  padding: 11px 42px 11px 14px;
}

.practice-type-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  border-top: 1px solid var(--separator);
  border-bottom: 1px solid var(--separator);
}

.practice-type-card {
  min-height: 150px;
  padding: 22px 20px;
  border: 0;
  border-right: 1px solid var(--separator);
  background: transparent;
  color: var(--text);
  text-align: left;
}

.practice-type-card:last-child {
  border-right: 0;
}

.practice-type-card:hover {
  background: rgba(255, 255, 255, 0.46);
}

.practice-type-card.selected {
  background: var(--surface);
  box-shadow: inset 0 -3px 0 var(--text);
}

.practice-type-card strong,
.practice-type-card small {
  display: block;
}

.practice-type-card strong {
  margin-top: 16px;
  font-size: 16px;
  font-weight: 650;
}

.practice-type-card small {
  margin-top: 5px;
  color: var(--text-secondary);
  line-height: 1.4;
}

.type-icon {
  display: inline-flex;
  min-width: 34px;
  height: 28px;
  align-items: center;
  justify-content: center;
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 700;
}

.quiz-card {
  padding-top: 12px;
}

.quiz-topline {
  display: flex;
  justify-content: space-between;
  margin-bottom: 12px;
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 600;
}

.quiz-body {
  min-height: 390px;
  padding: 58px 0 36px;
}

.quiz-body h2 {
  max-width: 760px;
  margin-bottom: 13px;
  font-size: clamp(34px, 5vw, 52px);
  font-weight: 700;
}

#question-instruction {
  margin-bottom: 26px;
  color: var(--text-secondary);
}

.text-answer,
.reply-answer {
  padding: 14px 15px;
  font-size: 17px;
}

.reply-answer {
  min-height: 120px;
  resize: vertical;
}

.choice-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.choice-btn {
  min-height: 54px;
  padding: 14px 16px;
  border: 1px solid var(--separator);
  border-radius: 12px;
  background: var(--surface);
  color: var(--text);
  text-align: left;
}

.choice-btn:hover:not(.correct):not(.incorrect) {
  background: var(--surface-muted);
}

.choice-btn.selected {
  border-color: var(--text-secondary);
  background: var(--surface-muted);
}

.choice-btn.correct {
  border-color: rgba(47, 107, 79, 0.45);
  background: var(--success-bg);
}

.choice-btn.incorrect {
  border-color: rgba(154, 53, 53, 0.4);
  background: var(--error-bg);
}

.feedback {
  margin-top: 18px;
  padding: 14px 0;
  border-top: 1px solid var(--separator);
}

.feedback.success {
  color: var(--success);
}

.feedback.error {
  color: var(--error);
}

.feedback.neutral {
  color: var(--text-secondary);
}

.quiz-actions {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  padding-top: 18px;
  border-top: 1px solid var(--separator-soft);
}

.result-card {
  padding: 44px 0;
  text-align: center;
}

.result-score {
  margin: 4px auto 18px;
  color: var(--text);
  font-size: 74px;
  font-weight: 720;
  letter-spacing: -0.06em;
}

.result-card h2 {
  font-size: 38px;
}

.result-card > p {
  color: var(--text-secondary);
}

.result-actions {
  justify-content: center;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  margin-bottom: 42px;
  border-top: 1px solid var(--separator);
  border-bottom: 1px solid var(--separator);
}

.stat-card {
  padding: 24px 18px;
  border-right: 1px solid var(--separator);
}

.stat-card:last-child {
  border-right: 0;
}

.stat-card span {
  color: var(--text-secondary);
  font-size: 14px;
}

.stat-card strong {
  display: block;
  margin-top: 5px;
  font-size: 36px;
  font-weight: 700;
  letter-spacing: -0.04em;
}

.progress-unit-list {
  border-top: 1px solid var(--separator);
}

.progress-row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 18px;
  padding: 20px 4px;
  border-bottom: 1px solid var(--separator-soft);
}

.progress-row p {
  margin: 3px 0 0;
  color: var(--text-secondary);
  font-size: 14px;
}

.progress-score {
  align-self: center;
  color: var(--text-secondary);
  font-weight: 650;
}

.hidden {
  display: none !important;
}

footer {
  padding: 28px 24px;
  border-top: 1px solid var(--separator-soft);
  color: var(--text-tertiary);
  text-align: center;
  font-size: 13px;
}

footer p {
  margin: 0;
}

@media (max-width: 860px) {
  .hero {
    grid-template-columns: 1fr;
    min-height: auto;
    padding-top: 72px;
  }

  .hero-card {
    max-width: 520px;
    padding: 24px 0 0;
    border-top: 1px solid var(--separator);
    border-left: 0;
  }

  .unit-layout {
    grid-template-columns: 1fr;
  }

  .unit-sidebar {
    display: none;
  }

  .unit-content {
    width: 100%;
  }

  .unit-title-row,
  .section-heading {
    align-items: start;
    flex-direction: column;
  }

  .practice-type-grid {
    grid-template-columns: 1fr;
  }

  .practice-type-card {
    min-height: auto;
    border-right: 0;
    border-bottom: 1px solid var(--separator);
  }

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

  .practice-type-card.selected {
    box-shadow: inset 3px 0 0 var(--text);
  }
}

@media (max-width: 640px) {
  body {
    padding-bottom: 70px;
  }

  .topbar {
    min-height: 58px;
    padding: 9px 16px;
  }

  .brand small {
    display: none;
  }

  .brand-mark {
    width: 34px;
    height: 34px;
  }

  .topnav {
    position: fixed;
    right: 12px;
    bottom: 10px;
    left: 12px;
    z-index: 40;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    padding: 5px;
    border: 1px solid rgba(255, 255, 255, 0.75);
    border-radius: 18px;
    background: rgba(238, 238, 239, 0.86);
    box-shadow: 0 10px 34px rgba(0, 0, 0, 0.12);
    backdrop-filter: saturate(180%) blur(22px);
    -webkit-backdrop-filter: saturate(180%) blur(22px);
  }

  .nav-btn {
    min-width: 0;
    min-height: 44px;
  }

  .hero {
    gap: 44px;
    padding: 58px 20px 56px;
  }

  .hero h1 {
    font-size: 46px;
  }

  .hero-copy > p {
    font-size: 18px;
  }

  .hero-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .hero-actions .primary-btn,
  .hero-actions .secondary-btn {
    width: 100%;
  }

  .section-shell {
    padding: 56px 20px 78px;
  }

  .unit-grid {
    grid-template-columns: 1fr;
  }

  .unit-card,
  .unit-card:nth-child(odd),
  .unit-card:nth-child(even) {
    padding: 19px 2px;
    border-right: 0;
  }

  .unit-badge {
    display: none;
  }

  .unit-content {
    padding: 50px 20px 80px;
  }

  .unit-title-row .primary-btn {
    width: 100%;
  }

  .content-tabs {
    margin-right: -20px;
  }

  .dialogue-line {
    grid-template-columns: 1fr;
    gap: 3px;
  }

  .choice-grid,
  .stats-grid {
    grid-template-columns: 1fr;
  }

  .stats-grid {
    border-bottom: 0;
  }

  .stat-card {
    border-right: 0;
    border-bottom: 1px solid var(--separator-soft);
  }

  .quiz-actions {
    align-items: stretch;
    flex-direction: column-reverse;
  }

  .quiz-actions button {
    width: 100%;
  }

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

  footer {
    display: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}