:root {
  --color-bg: #f5f6fa;
  --color-surface: #ffffff;
  --color-border: #d9dce3;
  --color-text: #1f2430;
  --color-text-muted: #5b6172;
  --color-primary: #2d5bff;
  --color-primary-dark: #1f42c9;
  --color-danger: #d63946;
  --color-danger-dark: #b32836;
  --color-correct-bg: #e4f7e9;
  --color-correct-text: #1c7a3c;
  --color-spelling-bg: #fff6df;
  --color-spelling-text: #8a6300;
  --color-wrong-bg: #fdeaec;
  --color-wrong-text: #a4222d;
  --radius: 10px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.5;
}

.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding: 1.25rem 1rem 0;
}

.site-header h1 {
  margin: 0 0 0.25rem;
  font-size: 1.6rem;
}

.site-subtitle {
  margin: 0 0 1rem;
  color: var(--color-text-muted);
}

.main-nav {
  display: flex;
  gap: 0.25rem;
  flex-wrap: wrap;
}

.main-nav button {
  border: none;
  background: transparent;
  padding: 0.7rem 1rem;
  font-size: 0.95rem;
  cursor: pointer;
  border-bottom: 3px solid transparent;
  color: var(--color-text-muted);
}

.main-nav button.active {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
  font-weight: 600;
}

.site-main {
  max-width: 960px;
  margin: 0 auto;
  padding: 1.25rem 1rem 3rem;
}

.site-footer {
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.85rem;
  padding: 1rem;
}

.panel {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.25rem;
  margin-bottom: 1rem;
}

.panel h2 {
  margin-top: 0;
}

.hint {
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

.hint code {
  background: var(--color-bg);
  padding: 0.1rem 0.3rem;
  border-radius: 4px;
}

button {
  font: inherit;
  cursor: pointer;
}

button:not(.btn-icon) {
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: 6px;
  padding: 0.55rem 1rem;
  margin: 0.15rem 0.3rem 0.15rem 0;
}

button:not(.btn-icon):hover {
  background: var(--color-primary-dark);
}

button.danger {
  background: var(--color-danger);
}

button.danger:hover {
  background: var(--color-danger-dark);
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-icon {
  border: none;
  background: transparent;
  color: var(--color-text-muted);
  font-size: 1rem;
  padding: 0.2rem 0.4rem;
}

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

input[type='text'],
input[type='number'],
select,
textarea {
  font: inherit;
  padding: 0.5rem;
  border: 1px solid var(--color-border);
  border-radius: 6px;
  background: var(--color-surface);
  color: var(--color-text);
  width: 100%;
}

.set-toolbar,
.game-toolbar {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  align-items: end;
  margin-bottom: 1rem;
}

.set-toolbar label,
.game-toolbar label {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  font-size: 0.9rem;
  min-width: 160px;
}

.table-scroll {
  overflow-x: auto;
  margin-bottom: 0.75rem;
}

table {
  border-collapse: collapse;
  width: 100%;
}

.vocab-table th,
.vocab-table td,
.review-table th,
.review-table td,
.scale-table th,
.scale-table td {
  border: 1px solid var(--color-border);
  padding: 0.4rem;
  text-align: left;
  vertical-align: top;
}

.vocab-table input {
  min-width: 140px;
}

.vocab-table th,
.review-table th,
.scale-table th {
  background: var(--color-bg);
  font-size: 0.85rem;
}

.io-toolbar {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  align-items: center;
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--color-border);
}

.file-import {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  font-size: 0.9rem;
}

.share-toolbar {
  flex-direction: column;
  align-items: stretch;
  gap: 0.5rem;
}

.share-link {
  margin: 0;
  word-break: break-all;
}

.hint-inline {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.quiz-config {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  margin: 1rem 0;
}

.quiz-config label {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  font-size: 0.9rem;
}

.quiz-config input {
  width: 6rem;
}

.warnings {
  margin-top: 0.75rem;
}

.quiz-panel .quiz-progress {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-bottom: 0.35rem;
}

.progress-bar {
  height: 6px;
  border-radius: 4px;
  background: var(--color-bg);
  overflow: hidden;
  margin-bottom: 1rem;
}

.progress-bar-fill {
  height: 100%;
  background: var(--color-primary);
}

.quiz-de-hint {
  color: var(--color-text-muted);
  margin: 0 0 0.25rem;
}

.quiz-prompt {
  font-size: 1.15rem;
  margin: 0 0 0.75rem;
}

.quiz-actions {
  margin-top: 0.75rem;
}

.feedback {
  padding: 0.6rem 0.75rem;
  border-radius: 6px;
  margin-top: 0.75rem;
  font-size: 0.95rem;
}

.feedback-correct {
  background: var(--color-correct-bg);
  color: var(--color-correct-text);
}

.feedback-spelling {
  background: var(--color-spelling-bg);
  color: var(--color-spelling-text);
}

.feedback-wrong {
  background: var(--color-wrong-bg);
  color: var(--color-wrong-text);
}

.model-sentence {
  background: var(--color-bg);
  padding: 0.6rem 0.75rem;
  border-radius: 6px;
}

.rubric {
  margin-top: 0.75rem;
  padding-top: 0.75rem;
  border-top: 1px dashed var(--color-border);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.rubric label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  max-width: 260px;
}

.rubric input {
  width: 5rem;
}

.results-summary {
  display: flex;
  gap: 1.25rem;
  align-items: center;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}

.grade-badge {
  font-size: 1.75rem;
  font-weight: 700;
  background: var(--color-bg);
  border-radius: var(--radius);
  padding: 0.75rem 1.25rem;
}

.review-table .row-correct {
  background: var(--color-correct-bg);
}

.review-table .row-spelling {
  background: var(--color-spelling-bg);
}

.review-table .row-wrong {
  background: var(--color-wrong-bg);
}

.game-status {
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

.memory-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(110px, 1fr));
  gap: 0.6rem;
  margin-top: 1rem;
}

.memory-card {
  aspect-ratio: 1.2 / 1;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  background: var(--color-primary);
  color: transparent;
  font-size: 0.95rem;
  padding: 0.4rem;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
}

.memory-card.flipped {
  background: var(--color-surface);
  color: var(--color-text);
}

.memory-card.matched {
  background: var(--color-correct-bg);
  color: var(--color-correct-text);
  border-color: var(--color-correct-text);
}

.scale-table input {
  width: 5rem;
  display: inline-block;
}

@media (max-width: 600px) {
  .site-header h1 {
    font-size: 1.35rem;
  }

  .grade-badge {
    font-size: 1.4rem;
  }
}