:root {
  --bg: #f7f7f8;
  --surface: #ffffff;
  --border: #e5e5ea;
  --text: #1c1c1e;
  --muted: #6b6b70;
  --primary: #0066ff;
  --primary-hover: #0050cc;
  --danger: #d93b3b;
  --success: #1f9b53;
  --warn: #c98318;
  --easy: #1f9b53;
  --medium: #c98318;
  --hard: #d93b3b;
  --radius: 8px;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.05), 0 4px 16px rgba(0, 0, 0, 0.04);
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font:
    14px/1.5 -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    Roboto,
    Helvetica,
    Arial,
    sans-serif;
}

.hidden {
  display: none !important;
}
.muted {
  color: var(--muted);
}

/* Topbar */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 20px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}
.brand {
  display: flex;
  align-items: baseline;
  gap: 8px;
}
.brand strong {
  font-size: 15px;
}
.topbar-right {
  display: flex;
  align-items: center;
  gap: 12px;
}
.auth-status {
  font-size: 13px;
}

/* Layout */
main {
  display: grid;
  grid-template-columns: 260px 1fr;
  min-height: calc(100vh - 53px);
}

.sidebar {
  background: var(--surface);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
}
.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 16px 8px;
}
.sidebar-header h2 {
  margin: 0;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
}

.topic-list {
  list-style: none;
  margin: 0;
  padding: 4px 8px;
  flex: 1;
}
.topic-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 10px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 14px;
}
.topic-item:hover {
  background: var(--bg);
}
.topic-item.active {
  background: rgba(0, 102, 255, 0.08);
  color: var(--primary);
}
.topic-item.dirty .topic-name::after {
  content: " •";
  color: var(--warn);
}
.topic-version {
  font-size: 11px;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

/* Content */
.content {
  padding: 24px 28px;
  max-width: 920px;
  width: 100%;
}
.content-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 16px;
}
.content-header h1 {
  margin: 0 0 4px;
  font-size: 22px;
  text-transform: capitalize;
}
.content-header p {
  margin: 0;
  font-size: 13px;
}
.content-actions {
  display: flex;
  gap: 8px;
}

.banner {
  background: #fff8e6;
  border: 1px solid #f3dc9c;
  color: #6a4d00;
  padding: 8px 12px;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
  font-size: 13px;
}

.empty-state {
  padding: 80px 0;
  text-align: center;
  color: var(--muted);
}

/* Question cards */
.questions {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.qcard {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 16px;
  box-shadow: var(--shadow);
}
.qcard-header {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 8px;
}
.qcard-num {
  font-size: 12px;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}
.qcard-actions {
  margin-left: auto;
  display: flex;
  gap: 6px;
}
.qcard-q {
  margin: 0 0 8px;
  font-weight: 500;
}
.qcard-opts {
  margin: 0 0 8px;
  padding-left: 22px;
  color: var(--text);
}
.qcard-opts li {
  padding: 1px 0;
}
.qcard-opts li.correct {
  color: var(--success);
  font-weight: 500;
}
.qcard-opts li.correct::after {
  content: " ✓";
}
.qcard-exp {
  margin: 0;
  font-size: 13px;
  font-style: italic;
}

/* Pills */
.pill {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 500;
  background: var(--bg);
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.diff-easy {
  background: rgba(31, 155, 83, 0.12);
  color: var(--easy);
}
.diff-medium {
  background: rgba(201, 131, 24, 0.12);
  color: var(--medium);
}
.diff-hard {
  background: rgba(217, 59, 59, 0.12);
  color: var(--hard);
}

/* Buttons */
.btn {
  appearance: none;
  border: 1px solid transparent;
  background: var(--surface);
  color: var(--text);
  font: inherit;
  padding: 6px 12px;
  border-radius: 6px;
  cursor: pointer;
  transition:
    background 0.15s,
    border-color 0.15s,
    color 0.15s;
}
.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}
.btn.small {
  padding: 4px 10px;
  font-size: 12px;
}
.btn.primary {
  background: var(--primary);
  color: white;
}
.btn.primary:hover:not(:disabled) {
  background: var(--primary-hover);
}
.btn.ghost {
  background: transparent;
  border-color: var(--border);
}
.btn.ghost:hover:not(:disabled) {
  background: var(--bg);
}
.btn.danger {
  background: transparent;
  color: var(--danger);
  border-color: var(--border);
}
.btn.danger:hover:not(:disabled) {
  background: rgba(217, 59, 59, 0.08);
  border-color: rgba(217, 59, 59, 0.3);
}

/* Modals */
.modal {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.35);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16px;
  z-index: 100;
}
.modal-card {
  background: var(--surface);
  border-radius: 12px;
  padding: 24px;
  width: 100%;
  max-width: 420px;
  box-shadow:
    0 10px 40px rgba(0, 0, 0, 0.2),
    0 2px 8px rgba(0, 0, 0, 0.1);
  max-height: 90vh;
  overflow-y: auto;
}
.modal-card.wide {
  max-width: 600px;
}
.modal-card h2 {
  margin: 0 0 12px;
  font-size: 18px;
}
.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: 8px;
  margin-top: 16px;
}

/* Forms */
form label {
  display: block;
  margin-bottom: 12px;
}
form label > span {
  display: block;
  font-size: 12px;
  color: var(--muted);
  margin-bottom: 4px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
form input,
form select,
form textarea {
  width: 100%;
  padding: 8px 10px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font: inherit;
  background: white;
  color: var(--text);
}
form input:focus,
form select:focus,
form textarea:focus {
  outline: 2px solid var(--primary);
  outline-offset: -1px;
  border-color: var(--primary);
}
form textarea {
  resize: vertical;
  min-height: 60px;
}
.options-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0 12px;
}
.row {
  display: flex;
  gap: 12px;
}
.row .grow {
  flex: 1;
}

/* Device flow */
.device-code {
  display: flex;
  align-items: center;
  gap: 12px;
  background: var(--bg);
  padding: 14px;
  border-radius: 8px;
  margin: 12px 0;
}
.device-code code {
  font-size: 22px;
  font-weight: 600;
  letter-spacing: 0.15em;
  font-family:
    ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  flex: 1;
}

/* Publish summary */
.publish-summary {
  background: var(--bg);
  border-radius: 6px;
  padding: 10px 16px 10px 28px;
  font-size: 13px;
  font-variant-numeric: tabular-nums;
  margin: 8px 0 16px;
}
.publish-summary li {
  margin: 2px 0;
}

/* Toast */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  background: #1c1c1e;
  color: white;
  padding: 10px 16px;
  border-radius: 6px;
  font-size: 13px;
  box-shadow: var(--shadow);
  z-index: 200;
}
.toast.success {
  background: var(--success);
}
.toast.error {
  background: var(--danger);
}