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

:root {
  --bg: #fafaf8;
  --surface: #ffffff;
  --border: #e8e8e4;
  --text: #1a1a18;
  --muted: #888880;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --danger: #dc2626;
  --success: #16a34a;
  --gold: #d97706;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  font-size: 16px;
  line-height: 1.6;
}

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 2rem 1.5rem;
}

h1, h2, h3 {
  font-weight: 600;
  letter-spacing: -0.02em;
}

/* ===== NAV ===== */
.nav {
  display: flex;
  justify-content: flex-end;
  align-items: center;
  gap: 1.5rem;
  padding: 1rem 0 2rem;
  font-size: 0.85rem;
}

.nav a { color: var(--muted); text-decoration: none; }
.nav a:hover { color: var(--text); }
.nav-user { color: var(--accent); font-size: 0.85rem; font-weight: 500; }

/* ===== HEADER ===== */
.site-header {
  margin-bottom: 2.5rem;
}

.site-title {
  font-size: clamp(1.8rem, 5vw, 2.5rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--text);
  margin-bottom: 0.25rem;
}

.site-title span { color: var(--accent); }

.site-subtitle {
  font-size: 0.9rem;
  color: var(--muted);
}

/* ===== STATS PANEL ===== */
.stats-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 2rem;
  margin-bottom: 1.5rem;
}

.total-count {
  margin-bottom: 1.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border);
}

.total-number {
  font-size: clamp(2.5rem, 6vw, 3.5rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--text);
  display: block;
  line-height: 1;
}

.total-label {
  font-size: 0.85rem;
  color: var(--muted);
  margin-top: 0.25rem;
}

.level-bars {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.level-bar {
  display: grid;
  grid-template-columns: 70px 1fr 50px;
  align-items: center;
  gap: 1rem;
  cursor: pointer;
  padding: 0.5rem;
  border-radius: 6px;
  border: 1px solid transparent;
  transition: all 0.15s;
}

.level-bar:hover {
  background: var(--bg);
  border-color: var(--border);
}

.level-bar.selected {
  background: #eff6ff;
  border-color: #bfdbfe;
}

.level-name {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--muted);
}

.level-track {
  height: 3px;
  background: var(--border);
  border-radius: 99px;
  overflow: hidden;
}

.level-fill {
  height: 100%;
  background: var(--accent);
  border-radius: 99px;
  transition: width 0.8s ease;
}

.level-count {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text);
  text-align: right;
}

/* ===== LEVEL SELECT ===== */
.level-select {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 1.5rem 0;
}

/* ===== BUTTONS ===== */
.btn {
  display: inline-block;
  font-size: 0.85rem;
  font-weight: 500;
  padding: 0.6rem 1.25rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  transition: all 0.15s;
  text-decoration: none;
  white-space: nowrap;
}

.btn:hover { background: var(--bg); border-color: #d1d5db; }
.btn:active { transform: scale(0.98); }

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

.btn-primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); }

.btn-block { display: block; width: 100%; text-align: center; }

.btn-danger {
  background: transparent;
  border-color: #fca5a5;
  color: var(--danger);
}

.btn-danger:hover { background: #fef2f2; }

.btn.selected {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

/* ===== FORMS ===== */
.form-group { margin-bottom: 1.25rem; }

.form-label {
  display: block;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--muted);
  margin-bottom: 0.4rem;
  letter-spacing: 0.02em;
}

.form-input {
  width: 100%;
  padding: 0.65rem 0.85rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface);
  color: var(--text);
  font-size: 0.95rem;
  font-family: inherit;
  outline: none;
  transition: border-color 0.15s;
}

.form-input:focus { border-color: var(--accent); }
.form-input::placeholder { color: var(--muted); }

/* ===== CARD ===== */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.75rem;
}

.card-title {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--muted);
  text-transform: uppercase;
  margin-bottom: 1.25rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border);
}

/* ===== QUIZ ===== */
.quiz-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
  font-size: 0.8rem;
  color: var(--muted);
}

.quiz-level-badge {
  font-weight: 600;
  color: var(--accent);
  background: #eff6ff;
  border: 1px solid #bfdbfe;
  padding: 0.2rem 0.6rem;
  border-radius: 99px;
  font-size: 0.75rem;
}

.question-text {
  font-size: clamp(1.1rem, 2.5vw, 1.35rem);
  font-weight: 600;
  letter-spacing: -0.01em;
  margin-bottom: 2rem;
  line-height: 1.5;
}

.choices {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.choice {
  padding: 0.85rem 1.1rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface);
  color: var(--text);
  font-size: 0.95rem;
  font-family: inherit;
  cursor: pointer;
  text-align: left;
  transition: all 0.15s;
}

.choice:hover:not(:disabled) {
  border-color: var(--accent);
  background: #eff6ff;
}

.choice.correct {
  border-color: var(--success);
  background: #f0fdf4;
  color: #15803d;
}

.choice.wrong {
  border-color: var(--danger);
  background: #fef2f2;
  color: var(--danger);
}

.choice:disabled { cursor: default; }

.explanation {
  margin-top: 1.25rem;
  padding: 0.85rem 1rem;
  background: #f8fafc;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.88rem;
  color: var(--muted);
  display: none;
}

.explanation.visible { display: block; }

/* ===== PROGRESS BAR ===== */
.progress-bar {
  height: 3px;
  background: var(--border);
  border-radius: 99px;
  margin-bottom: 1.5rem;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--accent);
  border-radius: 99px;
  transition: width 0.4s ease;
}

/* ===== RESULT ===== */
.result-score {
  text-align: center;
  padding: 2.5rem 0;
}

.score-number {
  font-size: clamp(3.5rem, 10vw, 5rem);
  font-weight: 700;
  letter-spacing: -0.04em;
  color: var(--text);
  line-height: 1;
}

.score-label {
  font-size: 0.9rem;
  color: var(--muted);
  margin-top: 0.5rem;
}

/* ===== TABLE ===== */
.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
}

.data-table th {
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--muted);
  text-transform: uppercase;
  padding: 0.5rem 0.75rem;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

.data-table td {
  padding: 0.7rem 0.75rem;
  border-bottom: 1px solid #f4f4f2;
  color: var(--text);
}

.data-table tr:last-child td { border-bottom: none; }
.data-table tr:hover td { background: var(--bg); }

/* ===== ALERT ===== */
.alert {
  padding: 0.7rem 0.9rem;
  border-radius: 8px;
  margin-bottom: 1rem;
  font-size: 0.88rem;
}

.alert-error { background: #fef2f2; color: var(--danger); border: 1px solid #fca5a5; }
.alert-success { background: #f0fdf4; color: var(--success); border: 1px solid #86efac; }

/* ===== MISC ===== */
.hidden { display: none !important; }

.loading-text {
  text-align: center;
  color: var(--muted);
  font-size: 0.88rem;
  padding: 2rem 0;
}

.divider {
  height: 1px;
  background: var(--border);
  margin: 2rem 0;
}

@media (max-width: 600px) {
  .level-bar { grid-template-columns: 55px 1fr 40px; }
  .card { padding: 1.25rem; }
}