:root {
  --ink: #17202a;
  --muted: #65727d;
  --line: #dce4e8;
  --paper: #fbfcfd;
  --panel: #ffffff;
  --teal: #007f7a;
  --teal-dark: #005f5b;
  --berry: #b7355b;
  --amber: #d7971f;
  --mint: #e7f6f2;
  --rose: #faeef2;
  --blue: #eaf2fb;
  --success: #207a42;
  --danger: #b93030;
  --shadow: 0 18px 45px rgba(23, 32, 42, 0.08);
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    linear-gradient(180deg, rgba(231, 246, 242, 0.9), rgba(251, 252, 253, 0.5) 34rem),
    var(--paper);
  color: var(--ink);
}

button,
input {
  font: inherit;
}

button {
  cursor: pointer;
}

.app-shell {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
  padding: 24px 0 48px;
}

.topbar {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 18px;
  align-items: center;
  padding: 28px;
  min-height: 180px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background:
    linear-gradient(135deg, rgba(255, 255, 255, 0.95), rgba(234, 242, 251, 0.9)),
    var(--panel);
  box-shadow: var(--shadow);
}

.eyebrow,
.subtitle,
.panel-heading p,
.exercise-title p,
.result,
.score-label {
  margin: 0;
  color: var(--muted);
}

.eyebrow {
  font-size: 0.84rem;
  font-weight: 700;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  margin: 0;
  line-height: 1.1;
  letter-spacing: 0;
}

h1 {
  margin-top: 8px;
  font-size: clamp(2.5rem, 9vw, 5.4rem);
}

.subtitle {
  margin-top: 8px;
  font-size: clamp(1rem, 2.5vw, 1.35rem);
}

.score-panel {
  display: grid;
  place-items: center;
  width: 118px;
  height: 118px;
  border: 1px solid rgba(0, 127, 122, 0.24);
  border-radius: 8px;
  background: var(--mint);
}

.score-panel strong {
  font-size: 2rem;
}

.tabs {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  margin: 16px 0;
}

.tab-button,
.segment,
.primary-button,
.secondary-button,
.ghost-button,
.know-button,
.mark-card-button {
  min-height: 44px;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--ink);
  font-weight: 700;
}

.tab-button.is-active {
  border-color: var(--teal);
  background: var(--teal);
  color: #fff;
}

.tab-panel {
  display: none;
}

.tab-panel.is-active {
  display: block;
}

.panel-heading {
  display: flex;
  gap: 16px;
  align-items: center;
  justify-content: space-between;
  margin: 22px 0 16px;
}

.panel-heading h2 {
  font-size: clamp(1.45rem, 4vw, 2.25rem);
}

.exercise-block,
.reference-section,
.flashcard-area {
  margin-top: 16px;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.92);
  box-shadow: 0 12px 30px rgba(23, 32, 42, 0.05);
}

.exercise-title {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  margin-bottom: 18px;
}

.number-badge {
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  width: 34px;
  height: 34px;
  border-radius: 8px;
  background: var(--rose);
  color: var(--berry);
  font-weight: 800;
}

.grid {
  display: grid;
  gap: 12px;
}

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

.answer-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(120px, 0.55fr);
  gap: 10px;
  align-items: center;
  min-height: 58px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
}

.prompt {
  font-weight: 700;
  overflow-wrap: anywhere;
}

.answer-row input {
  width: 100%;
  min-height: 42px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 9px 10px;
  background: #fff;
}

.answer-row input:focus,
.pattern-answer-line input:focus,
.tab-button:focus-visible,
.primary-button:focus-visible,
.secondary-button:focus-visible,
.ghost-button:focus-visible,
.know-button:focus-visible,
.mark-card-button:focus-visible,
.char-button:focus-visible,
.segment:focus-visible,
.choice:focus-visible,
.combo-mark:focus-visible,
.flashcard:focus-visible {
  outline: 3px solid rgba(215, 151, 31, 0.45);
  outline-offset: 2px;
}

.answer-row.is-correct,
.pattern-item.is-correct {
  border-color: rgba(32, 122, 66, 0.5);
  background: #f0fbf3;
}

.answer-row.is-wrong,
.pattern-item.is-wrong {
  border-color: rgba(185, 48, 48, 0.45);
  background: #fff3f3;
}

.char-toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  align-items: center;
  margin: -2px 0 16px;
  color: var(--muted);
  font-size: 0.95rem;
  font-weight: 700;
}

.char-button {
  min-width: 34px;
  min-height: 34px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  color: var(--ink);
  font-weight: 800;
}

.char-button:hover {
  border-color: var(--teal);
  background: var(--mint);
}

.pattern-list {
  display: grid;
  gap: 14px;
}

.exercise-example {
  max-width: 620px;
  margin: -2px 0 18px;
  color: var(--ink);
}

.example-heading {
  display: flex;
  gap: 5px;
  align-items: baseline;
  font-size: 1.28rem;
  line-height: 1.2;
}

.example-heading span {
  text-decoration: underline;
  text-underline-offset: 3px;
}

.example-heading em {
  color: var(--muted);
  font-style: italic;
}

.example-line {
  display: grid;
  grid-template-columns: 100px minmax(180px, 1fr);
  gap: 18px;
  align-items: end;
  margin-top: 6px;
  font-size: 1.12rem;
}

.example-word mark {
  background: #eff400;
  color: inherit;
  padding: 0 1px;
}

.example-answer {
  display: block;
  padding-bottom: 2px;
  border-bottom: 1px solid var(--ink);
}

.bracket-text {
  font-style: italic;
}

.pattern-item {
  display: grid;
  grid-template-columns: minmax(130px, 0.25fr) minmax(220px, 1fr);
  gap: 22px;
  align-items: end;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
}

.pattern-word {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  font-size: 1.2rem;
  font-weight: 800;
}

.combo-mark {
  display: inline;
  min-height: 0;
  border: 0;
  border-radius: 0;
  background: transparent;
  color: inherit;
  padding: 0 1px;
  font-weight: 800;
  line-height: 1.2;
}

.combo-mark.is-marked {
  background: #eff400;
}

.combo-mark.is-wrong-mark {
  background: #ffd7d7;
  box-shadow: inset 0 -2px 0 rgba(185, 48, 48, 0.55);
}

.combo-mark.is-solution {
  background: #d8f5df;
  box-shadow: inset 0 -2px 0 rgba(32, 122, 66, 0.5);
}

.pattern-answer-line input {
  width: 100%;
  min-height: 42px;
  border: 0;
  border-bottom: 1px solid var(--ink);
  border-radius: 0;
  background: transparent;
  padding: 8px 6px 4px;
}

.pattern-answer-line input::placeholder {
  color: #9aa4ad;
}

.choice-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.choice {
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
  padding: 8px 10px;
  font-weight: 700;
}

.choice.is-selected {
  border-color: var(--teal);
  background: var(--mint);
  color: var(--teal-dark);
}

.choice.is-solution {
  border-color: rgba(32, 122, 66, 0.7);
  background: #f0fbf3;
  color: var(--success);
}

.word-ribbon {
  margin: 0 0 14px;
  padding: 14px;
  border-radius: 8px;
  background: var(--blue);
  font-weight: 800;
  line-height: 1.7;
  overflow-wrap: anywhere;
}

.word-ribbon mark {
  background: #eff400;
  color: inherit;
  padding: 0 1px;
}

.hidden-word-example {
  display: grid;
  grid-template-columns: auto minmax(120px, 1fr);
  gap: 6px;
  align-items: end;
  max-width: 150px;
  margin: 0 0 14px;
  font-size: 1.12rem;
}

.hidden-word-answer {
  display: block;
  padding-bottom: 2px;
  border-bottom: 1px solid var(--ink);
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
  margin-top: 16px;
}

.primary-button {
  border-color: var(--teal);
  background: var(--teal);
  color: #fff;
  padding: 0 18px;
}

.primary-button:hover {
  background: var(--teal-dark);
}

.secondary-button,
.ghost-button,
.know-button,
.mark-card-button {
  padding: 0 16px;
}

.secondary-button:hover,
.ghost-button:hover,
.segment:hover {
  border-color: var(--teal);
}

.know-button {
  border-color: rgba(32, 122, 66, 0.5);
  background: #f0fbf3;
  color: var(--success);
}

.mark-card-button {
  display: inline-grid;
  place-items: center;
  min-width: 48px;
  padding: 0 12px;
  font-size: 1.45rem;
  line-height: 1;
}

.mark-card-button.learned {
  border-color: rgba(32, 122, 66, 0.55);
  color: var(--success);
}

.mark-card-button.review {
  border-color: rgba(185, 48, 48, 0.45);
  color: var(--danger);
}

.mark-card-button.learned.is-active,
.mark-card-button.learned:hover {
  background: #f0fbf3;
  border-color: var(--success);
}

.mark-card-button.review.is-active,
.mark-card-button.review:hover {
  background: #fff3f3;
  border-color: var(--danger);
}

.mark-card-button:disabled,
.flashcard:disabled,
.secondary-button:disabled,
.primary-button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.result {
  font-weight: 700;
}

.result.good {
  color: var(--success);
}

.result.needs-work {
  color: var(--danger);
}

.segmented {
  display: inline-flex;
  gap: 6px;
  padding: 4px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
}

.segment {
  min-height: 38px;
  border-color: transparent;
  padding: 0 12px;
}

.segment.is-active {
  background: var(--berry);
  color: #fff;
}

.flashcard-area {
  display: grid;
  gap: 16px;
}

.flash-filter-bar {
  display: flex;
  justify-content: center;
}

.flashcard {
  position: relative;
  display: grid;
  place-items: center;
  width: 100%;
  min-height: 260px;
  padding: 38px 22px;
  border: 1px solid rgba(0, 127, 122, 0.25);
  border-radius: 8px;
  background:
    linear-gradient(135deg, rgba(231, 246, 242, 1), rgba(250, 238, 242, 0.9)),
    #fff;
  color: var(--ink);
  text-align: center;
  box-shadow: 0 12px 28px rgba(0, 95, 91, 0.08);
}

.card-meta {
  position: absolute;
  top: 14px;
  right: 14px;
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 700;
}

.card-front,
.card-back {
  display: block;
  max-width: 780px;
  font-size: clamp(2rem, 8vw, 4.5rem);
  font-weight: 850;
  line-height: 1.08;
  overflow-wrap: anywhere;
}

.card-back {
  display: none;
  color: var(--teal-dark);
  font-size: clamp(1.7rem, 6vw, 3.4rem);
}

.flashcard.is-flipped .card-front {
  display: none;
}

.flashcard.is-flipped .card-back {
  display: block;
}

.flash-actions,
.flash-progress {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  justify-content: center;
}

.flash-progress {
  justify-content: space-between;
  color: var(--muted);
  font-weight: 700;
}

.alphabet-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(76px, 1fr));
  gap: 8px;
}

.reference-notes {
  display: grid;
  gap: 14px;
  margin: 18px 0 0;
  color: var(--ink);
  font-size: 1.08rem;
  line-height: 1.45;
}

.reference-notes p {
  margin: 0;
  padding: 10px 12px;
  border: 1px solid #f0a31a;
  background: #fff8e9;
}

.reference-notes span {
  color: #f0a31a;
  font-weight: 900;
}

.letter-tile {
  min-height: 76px;
  display: grid;
  place-items: center;
  gap: 2px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  text-align: center;
}

.letter-tile strong {
  font-size: 1.45rem;
}

.letter-tile span {
  color: var(--muted);
  font-weight: 700;
}

.table-wrap {
  width: 100%;
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: 8px;
}

table {
  width: 100%;
  min-width: 680px;
  border-collapse: collapse;
  background: var(--panel);
}

th,
td {
  padding: 13px 14px;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

th {
  background: var(--mint);
}

tr:last-child td {
  border-bottom: 0;
}

@media (max-width: 760px) {
  .app-shell {
    width: min(100% - 20px, 1120px);
    padding-top: 10px;
  }

  .topbar,
  .panel-heading,
  .pattern-item {
    grid-template-columns: 1fr;
  }

  .topbar {
    padding: 22px;
  }

  .score-panel {
    width: 100%;
    height: auto;
    min-height: 82px;
  }

  .tabs,
  .two-col {
    grid-template-columns: 1fr;
  }

  .panel-heading {
    align-items: stretch;
  }

  .exercise-block,
  .reference-section,
  .flashcard-area {
    padding: 16px;
  }

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