*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #f5f5f7;
  --surface: #ffffff;
  --border: #e5e5ea;
  --text: #1c1c1e;
  --text-secondary: #6c6c70;
  --accent: #007aff;
  --accent-hover: #0062cc;
  --correct: #34c759;
  --error: #ff3b30;
  --warning: #ff9500;
  --radius: 12px;
  --shadow: 0 2px 12px rgba(0,0,0,0.08);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.5;
}

/* Nav */
.nav {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 0 1.5rem;
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 10;
}
.nav-brand { font-weight: 700; font-size: 1.05rem; color: var(--accent); }
.nav-links { display: flex; align-items: center; gap: 0.25rem; }
.nav-link {
  padding: 0.35rem 0.75rem;
  border-radius: 8px;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.9rem;
  transition: background 0.15s;
}
.nav-link:hover, .nav-link.active { background: var(--bg); color: var(--text); }
.nav-user { padding: 0.35rem 0.75rem; font-size: 0.9rem; color: var(--text-secondary); }

.main { padding: 2rem 1.5rem; max-width: 900px; margin: 0 auto; }

/* Cards */
.card {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 2rem;
  border: 1px solid var(--border);
}
.card-center { max-width: 480px; margin: 3rem auto; text-align: center; }
.card-title { font-size: 1.4rem; font-weight: 700; margin-bottom: 1.5rem; }
.card-subtitle { font-size: 1rem; font-weight: 600; margin-bottom: 1rem; color: var(--text); }

/* Login */
.login-body { display: flex; align-items: center; justify-content: center; min-height: 100vh; }
.login-card {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 2.5rem;
  width: 100%;
  max-width: 380px;
  border: 1px solid var(--border);
}
.login-title { font-size: 1.6rem; font-weight: 700; text-align: center; margin-bottom: 0.25rem; }
.login-subtitle { text-align: center; color: var(--text-secondary); font-size: 0.9rem; margin-bottom: 2rem; }
.login-form { display: flex; flex-direction: column; gap: 0.75rem; }

/* Form */
.field-label { font-size: 0.85rem; font-weight: 600; color: var(--text-secondary); display: block; margin-bottom: 0.25rem; }
.field-input {
  width: 100%;
  padding: 0.6rem 0.85rem;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  font-size: 0.95rem;
  background: var(--surface);
  color: var(--text);
  transition: border-color 0.15s;
  outline: none;
}
.field-input:focus { border-color: var(--accent); }

/* Buttons */
.btn {
  padding: 0.6rem 1.25rem;
  border: none;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, opacity 0.15s;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.btn:disabled { opacity: 0.5; cursor: not-allowed; }
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover:not(:disabled) { background: var(--accent-hover); }
.btn-secondary { background: var(--bg); color: var(--text); border: 1.5px solid var(--border); }
.btn-secondary:hover { background: #e5e5ea; }
.btn-outline { background: transparent; color: var(--accent); border: 1.5px solid var(--accent); }
.btn-outline:hover { background: rgba(0,122,255,0.06); }
.btn-full { width: 100%; }
.btn-flag {
  width: 40px;
  height: 40px;
  padding: 0;
  border-radius: 8px;
  font-size: 1.1rem;
  background: var(--bg);
  border: 1.5px solid var(--border);
  cursor: pointer;
  color: var(--text-secondary);
  transition: all 0.15s;
  flex-shrink: 0;
}
.btn-flag:hover { background: #fff3cd; border-color: var(--warning); color: var(--warning); }
.btn-flag.flagged { background: #fff3cd; border-color: var(--warning); color: var(--warning); }

/* Language selector */
.lang-grid { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; }
.lang-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  padding: 1.5rem 2rem;
  background: var(--bg);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  transition: all 0.15s;
  min-width: 130px;
}
.lang-card:hover { border-color: var(--accent); background: rgba(0,122,255,0.04); }
.lang-flag { font-size: 2.5rem; }
.lang-name { font-weight: 700; font-size: 1rem; }

/* Loading */
.spinner {
  width: 40px; height: 40px;
  border: 3px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
  margin: 0 auto 1rem;
}
@keyframes spin { to { transform: rotate(360deg); } }
.loading-text { font-weight: 600; font-size: 1rem; }
.loading-sub { color: var(--text-secondary); margin-top: 0.25rem; }

/* Quiz layout */
.quiz-layout {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 1.5rem;
  align-items: start;
}
@media (max-width: 640px) {
  .quiz-layout { grid-template-columns: 1fr; }
}

/* Stats panel */
.stats-panel {
  background: var(--surface);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  padding: 1.25rem;
  position: sticky;
  top: 68px;
}
.stats-title { font-weight: 700; font-size: 0.9rem; margin-bottom: 1rem; color: var(--accent); }
.stat-row { display: flex; justify-content: space-between; align-items: center; padding: 0.35rem 0; border-bottom: 1px solid var(--bg); }
.stat-row:last-of-type { border-bottom: none; }
.stat-label { font-size: 0.82rem; color: var(--text-secondary); }
.stat-value { font-weight: 700; font-size: 1rem; }
.correct-color { color: var(--correct); }
.error-color { color: var(--error); }
.mt-4 { margin-top: 1rem; }

/* Quiz main */
.quiz-main { display: flex; flex-direction: column; gap: 1rem; }

/* Badge */
.badge {
  display: inline-block;
  padding: 0.2rem 0.6rem;
  border-radius: 6px;
  font-size: 0.78rem;
  font-weight: 600;
  align-self: flex-start;
}
.badge-repeat { background: #fff3cd; color: #856404; }
.badge-generated { background: #d1ecf1; color: #0c5460; }
.badge-manual { background: var(--bg); color: var(--text-secondary); }

/* Question card */
.question-card {
  background: var(--surface);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  padding: 1.75rem;
  box-shadow: var(--shadow);
}
.question-label { font-size: 0.85rem; color: var(--text-secondary); margin-bottom: 0.5rem; }
.question-text { font-size: 1.5rem; font-weight: 600; }

/* Answer */
.input-row { display: flex; gap: 0.5rem; align-items: center; }
.btn-row { display: flex; gap: 0.75rem; margin-top: 0.75rem; }

/* Feedback */
.feedback-box {
  padding: 1rem 1.25rem;
  border-radius: 8px;
  font-weight: 600;
  font-size: 1rem;
}
.feedback-correct { background: #d4edda; color: #155724; }
.feedback-wrong { background: #f8d7da; color: #721c24; }
.correct-answer {
  margin-top: 0.5rem;
  padding: 0.75rem 1rem;
  background: #fff3cd;
  border-radius: 8px;
  font-size: 0.9rem;
  color: #856404;
}
.retry-label { font-size: 0.9rem; color: var(--text-secondary); margin-bottom: 0.5rem; margin-top: 1rem; }
.explanation {
  margin-top: 0.75rem;
  padding: 1rem;
  background: var(--bg);
  border-radius: 8px;
  font-size: 0.9rem;
  line-height: 1.6;
  white-space: pre-wrap;
}

/* Alert */
.alert { padding: 0.75rem 1rem; border-radius: 8px; margin-bottom: 1rem; font-size: 0.9rem; }
.alert-error { background: #f8d7da; color: #721c24; }

/* Screen utility */
.screen { width: 100%; }
.hidden { display: none !important; }

/* Vocabulary page */
.vocab-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.25rem;
  flex-wrap: wrap;
  gap: 0.75rem;
}
.page-title { font-size: 1.5rem; font-weight: 700; }
.lang-tabs { display: flex; gap: 0.5rem; }
.tab-btn {
  padding: 0.4rem 1rem;
  border-radius: 8px;
  border: 1.5px solid var(--border);
  background: var(--surface);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  color: var(--text-secondary);
  transition: all 0.15s;
}
.tab-btn.active { background: var(--accent); color: #fff; border-color: var(--accent); }
.tab-btn:hover:not(.active) { background: var(--bg); color: var(--text); }

.add-card { margin-bottom: 1.25rem; }
.add-form { display: flex; gap: 0.75rem; align-items: flex-start; flex-wrap: wrap; }
.add-fields { display: flex; flex: 1; gap: 0.75rem; flex-wrap: wrap; }
.add-fields .field-input { flex: 1; min-width: 160px; }
.add-hint { font-size: 0.8rem; color: var(--text-secondary); margin-top: 0.6rem; }

.vocab-meta { font-size: 0.85rem; color: var(--text-secondary); margin-bottom: 0.5rem; }

.table-wrap {
  background: var(--surface);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  overflow: hidden;
  box-shadow: var(--shadow);
}
.entry-table { width: 100%; border-collapse: collapse; font-size: 0.9rem; }
.entry-table th {
  background: var(--bg);
  padding: 0.75rem 1rem;
  text-align: left;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.entry-table td { padding: 0.65rem 1rem; border-top: 1px solid var(--border); vertical-align: middle; }
.entry-table tr:hover td { background: var(--bg); }
.cell-target, .cell-native { max-width: 300px; }
.cell-actions { white-space: nowrap; text-align: right; }

.btn-icon {
  padding: 0.3rem 0.5rem;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.9rem;
  background: transparent;
  color: var(--text-secondary);
  transition: all 0.15s;
}
.btn-icon:hover { background: var(--bg); }
.btn-save:hover { color: var(--correct); }
.btn-delete:hover { color: var(--error); }
.btn-edit:hover { color: var(--accent); }

.empty-state, .loading-state { padding: 2rem; text-align: center; color: var(--text-secondary); font-size: 0.9rem; }

/* Summary */
.batch-textarea { width: 100%; resize: vertical; font-family: inherit; margin-bottom: 0.75rem; }
.batch-actions { display: flex; align-items: center; gap: 1rem; }
.batch-status { font-size: 0.875rem; }
.batch-status--loading { color: var(--text-secondary); }
.batch-status--ok { color: var(--correct); }
.batch-status--error { color: var(--error); }

.summary-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin: 1.5rem 0; }
.summary-stat { display: flex; flex-direction: column; align-items: center; gap: 0.25rem; }
.summary-num { font-size: 2rem; font-weight: 700; }
.summary-label { font-size: 0.85rem; color: var(--text-secondary); }