:root {
  --bg: #f4f5f7;
  --bg-elevated: #ffffff;
  --card: #ffffff;
  --text: #1a1c23;
  --text-muted: #6b7280;
  --border: #e5e7eb;
  --accent: #4f46e5;
  --accent-hover: #4338ca;
  --accent-text: #ffffff;
  --success: #16a34a;
  --success-bg: #dcfce7;
  --danger: #dc2626;
  --danger-bg: #fee2e2;
  --warning-bg: #fef9c3;
  --warning-text: #854d0e;
  --radius: 14px;
  --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
}

[data-theme="dark"] {
  --bg: #14161c;
  --bg-elevated: #1c1f27;
  --card: #1c1f27;
  --text: #eef0f4;
  --text-muted: #9199a8;
  --border: #2b2f3a;
  --accent: #6366f1;
  --accent-hover: #7476f3;
  --accent-text: #ffffff;
  --success: #4ade80;
  --success-bg: #14301f;
  --danger: #f87171;
  --danger-bg: #3a1a1a;
  --warning-bg: #3a3319;
  --warning-text: #fde68a;
  --shadow: 0 1px 3px rgba(0,0,0,0.4), 0 1px 2px rgba(0,0,0,0.3);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  transition: background 0.2s ease, color 0.2s ease;
}

#app {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a { color: var(--accent); }

button {
  font-family: inherit;
  cursor: pointer;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 10px 18px;
  border-radius: 10px;
  border: 1px solid transparent;
  font-size: 14px;
  font-weight: 600;
  transition: background 0.15s ease, transform 0.05s ease;
}
.btn:active { transform: scale(0.98); }
.btn-primary { background: var(--accent); color: var(--accent-text); }
.btn-primary:hover { background: var(--accent-hover); }
.btn-secondary { background: transparent; color: var(--text); border-color: var(--border); }
.btn-secondary:hover { background: var(--border); }
.btn-danger { background: var(--danger-bg); color: var(--danger); }
.btn-block { width: 100%; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

input, select {
  width: 100%;
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg-elevated);
  color: var(--text);
  font-size: 14px;
}
input:focus, select:focus { outline: 2px solid var(--accent); outline-offset: 1px; }

label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  margin-bottom: 6px;
  color: var(--text-muted);
}

.field { margin-bottom: 14px; }

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 20px;
  border-bottom: 1px solid var(--border);
  background: var(--bg-elevated);
  position: sticky;
  top: 0;
  z-index: 10;
}
.topbar .brand { font-weight: 800; font-size: 18px; display: flex; align-items: center; gap: 8px; }
.topbar-actions { display: flex; align-items: center; gap: 10px; }
.icon-btn {
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 10px;
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text);
  font-size: 16px;
}
.icon-btn:hover { background: var(--border); }

.icon-svg { display: block; flex-shrink: 0; }
.mode-card .icon-svg { color: var(--accent); }
.brand-header .icon-svg, .brand .icon-svg { color: var(--accent); }

.password-field-wrap {
  position: relative;
}
.password-field-wrap input {
  padding-right: 42px;
}
.password-toggle-btn {
  position: absolute;
  top: 50%;
  right: 6px;
  transform: translateY(-50%);
  background: transparent;
  border: none;
  color: var(--text-muted);
  width: 30px;
  height: 30px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 8px;
}
.password-toggle-btn:hover { color: var(--text); background: var(--border); }

select.lang-select {
  width: auto;
  padding: 8px 10px;
}

main {
  flex: 1;
  width: 100%;
  max-width: 880px;
  margin: 0 auto;
  padding: 24px 20px 24px;
  display: flex;
  flex-direction: column;
}

.centered-screen {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.auth-card {
  width: 100%;
  max-width: 380px;
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 32px 28px;
  border: 1px solid var(--border);
}
.auth-card h1 { margin-top: 0; font-size: 22px; }
.auth-card .brand-header {
  display: flex; align-items: center; gap: 10px; margin-bottom: 18px; font-weight: 800; font-size: 20px;
}

.error-banner {
  background: var(--danger-bg);
  color: var(--danger);
  padding: 10px 14px;
  border-radius: 10px;
  font-size: 13px;
  margin-bottom: 14px;
}
.info-banner {
  background: var(--warning-bg);
  color: var(--warning-text);
  padding: 10px 14px;
  border-radius: 10px;
  font-size: 13px;
  margin-bottom: 14px;
}
.success-banner {
  background: var(--success-bg);
  color: var(--success);
  padding: 10px 14px;
  border-radius: 10px;
  font-size: 13px;
  margin-bottom: 14px;
}

h1, h2, h3 { letter-spacing: -0.01em; }

.greeting { font-size: 22px; font-weight: 700; margin-bottom: 4px; }
.subtle { color: var(--text-muted); font-size: 14px; }

.stats-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin: 20px 0 24px;
}
.stat-box {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px;
  text-align: center;
}
.stat-box .value { font-size: 22px; font-weight: 800; }
.stat-box .label { font-size: 12px; color: var(--text-muted); margin-top: 2px; }

.card-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
}
@media (max-width: 520px) {
  .card-grid { grid-template-columns: 1fr; }
}

.mode-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
  text-align: left;
  display: flex;
  flex-direction: column;
  gap: 8px;
  transition: transform 0.1s ease, border-color 0.15s ease;
}
.mode-card:hover { border-color: var(--accent); transform: translateY(-1px); }
.mode-card .mode-icon {
  width: 42px;
  height: 42px;
  border-radius: 12px;
  background: var(--bg);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
}
.mode-card h3 { margin: 0; font-size: 17px; }
.mode-card p { margin: 0; color: var(--text-muted); font-size: 13px; line-height: 1.4; }

.progress-bar {
  height: 8px;
  border-radius: 6px;
  background: var(--border);
  overflow: hidden;
  margin-bottom: 20px;
}
.progress-bar-fill {
  height: 100%;
  background: var(--accent);
  transition: width 0.2s ease;
}

.question-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px;
}
.question-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--text-muted);
  font-size: 13px;
  margin-bottom: 10px;
}
.question-text { font-size: 17px; font-weight: 600; margin: 0 0 18px; line-height: 1.45; }

.options-list { display: flex; flex-direction: column; gap: 10px; }
.option-btn {
  text-align: left;
  padding: 12px 14px;
  border-radius: 12px;
  border: 1.5px solid var(--border);
  background: var(--bg-elevated);
  color: var(--text);
  font-size: 14px;
  line-height: 1.4;
  display: flex;
  gap: 10px;
  align-items: flex-start;
}
.option-btn:hover:not(:disabled) { border-color: var(--accent); }
.option-btn .bullet {
  flex-shrink: 0;
  width: 22px; height: 22px;
  border-radius: 50%;
  border: 1.5px solid var(--border);
  display: flex; align-items: center; justify-content: center;
  font-size: 12px; font-weight: 700;
  color: var(--text-muted);
}
.option-btn.selected { border-color: var(--accent); background: color-mix(in srgb, var(--accent) 10%, var(--bg-elevated)); }
.option-btn.selected .bullet { border-color: var(--accent); color: var(--accent); }
.option-btn.correct { border-color: var(--success); background: var(--success-bg); }
.option-btn.correct .bullet { border-color: var(--success); background: var(--success); color: white; }
.option-btn.incorrect { border-color: var(--danger); background: var(--danger-bg); }
.option-btn.incorrect .bullet { border-color: var(--danger); background: var(--danger); color: white; }
.option-btn:disabled { cursor: default; }

.feedback-box {
  margin-top: 16px;
  padding: 12px 14px;
  border-radius: 12px;
  font-size: 14px;
  font-weight: 600;
}
.feedback-box.correct { background: var(--success-bg); color: var(--success); }
.feedback-box.incorrect { background: var(--danger-bg); color: var(--danger); }

.quiz-nav {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  position: sticky;
  bottom: 0;
  padding: 16px 0;
  background: var(--bg);
  z-index: 50;
  margin-top: auto;
}

.timer-pill {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 6px 14px;
  font-weight: 700;
  font-size: 13px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.timer-pill.low-time { color: var(--danger); border-color: var(--danger); }

.results-summary {
  text-align: center;
  padding: 30px 20px;
  background: var(--card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  margin-bottom: 24px;
}
.results-summary .big-score { font-size: 42px; font-weight: 800; margin: 8px 0; }
.results-summary .status-pill {
  display: inline-block;
  padding: 6px 16px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 13px;
}
.results-summary .status-pill.passed { background: var(--success-bg); color: var(--success); }
.results-summary .status-pill.failed { background: var(--danger-bg); color: var(--danger); }

.review-item {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 18px;
  margin-bottom: 12px;
  cursor: pointer;
}
.review-item:hover { border-color: var(--accent); }
.review-item .q-text { font-weight: 600; margin-bottom: 6px; }
.review-item .q-answers { font-size: 13px; color: var(--text-muted); }
.review-item .q-answers .wrong-ans { color: var(--danger); }
.review-item .q-answers .right-ans { color: var(--success); }

.topics-list .topic-item {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 14px 16px;
  margin-bottom: 10px;
}
.topics-list .topic-item .q-num { color: var(--text-muted); font-size: 12px; font-weight: 700; }
.topics-list .topic-item .q-text { font-weight: 600; margin: 4px 0 8px; }
.topics-list .opt-row { font-size: 13px; padding: 6px 8px; border-radius: 8px; margin-bottom: 4px; }
.topics-list .opt-row.correct-opt { background: var(--success-bg); color: var(--success); font-weight: 600; }

.history-item {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 18px;
  margin-bottom: 12px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 10px;
}
.history-item .h-left { display: flex; flex-direction: column; gap: 4px; }
.history-item .h-date { font-size: 12px; color: var(--text-muted); }
.history-item .h-score { font-weight: 700; }
.badge {
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 700;
}
.badge.passed { background: var(--success-bg); color: var(--success); }
.badge.failed { background: var(--danger-bg); color: var(--danger); }
.badge.mode { background: var(--border); color: var(--text-muted); }

table.admin-table {
  width: 100%;
  border-collapse: collapse;
  background: var(--card);
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
}
table.admin-table th, table.admin-table td {
  padding: 12px 14px;
  text-align: left;
  border-bottom: 1px solid var(--border);
  font-size: 13px;
  vertical-align: top;
}
table.admin-table th { color: var(--text-muted); font-weight: 700; font-size: 12px; text-transform: uppercase; letter-spacing: 0.03em; }
table.admin-table tr:last-child td { border-bottom: none; }
.table-scroll { overflow-x: auto; }

.row-actions { display: flex; gap: 6px; flex-wrap: wrap; }
.row-actions .btn { padding: 6px 10px; font-size: 12px; }

.modal-backdrop {
  position: fixed; inset: 0;
  background: rgba(0,0,0,0.4);
  display: flex; align-items: center; justify-content: center;
  z-index: 100;
  padding: 20px;
}
.modal {
  background: var(--card);
  border-radius: var(--radius);
  padding: 24px;
  max-width: 420px;
  width: 100%;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
}
.modal h3 { margin-top: 0; }
.modal .modal-actions { display: flex; gap: 10px; justify-content: flex-end; margin-top: 18px; }

.password-reveal {
  font-family: 'SF Mono', Consolas, Monaco, monospace;
  font-size: 20px;
  font-weight: 700;
  background: var(--bg);
  border: 1px dashed var(--border);
  border-radius: 10px;
  padding: 12px;
  text-align: center;
  letter-spacing: 2px;
  margin: 14px 0;
  user-select: all;
}

.section-title { display: flex; align-items: center; justify-content: space-between; margin-bottom: 14px; }

.empty-state { text-align: center; color: var(--text-muted); padding: 40px 20px; }

.search-box { margin-bottom: 16px; }

footer.app-footer {
  text-align: center;
  color: var(--text-muted);
  font-size: 12px;
  padding: 20px;
}