/* CBT — Material 3 / Android-inspired design system */

:root {
  --md-primary: #1b6ef3;
  --md-primary-container: #d3e3fd;
  --md-on-primary: #ffffff;
  --md-surface: #ffffff;
  --md-surface-dim: #f4f6fa;
  --md-surface-container: #eef1f6;
  --md-surface-container-high: #e8ecf2;
  --md-on-surface: #1a1c1e;
  --md-on-surface-variant: #5f6368;
  --md-outline-variant: #e0e4ea;
  --md-error: #dc362e;
  --md-error-container: #ffdad6;
  --md-success: #1e8e3e;
  --md-success-container: #ceead6;
  --md-warning: #f9ab00;
  --md-warning-container: #fef0c7;
  --md-elevation-1: 0 1px 2px rgba(0, 0, 0, 0.06), 0 1px 3px rgba(0, 0, 0, 0.04);
  --md-elevation-2: 0 2px 6px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.04);
  --md-elevation-3: 0 4px 12px rgba(0, 0, 0, 0.1);
  --md-radius-sm: 12px;
  --md-radius-md: 16px;
  --md-radius-lg: 28px;
  --md-radius-full: 9999px;
  --app-max: 480px;
  --topbar-h: 64px;
  --bottombar-h: 72px;
  font-family: 'Google Sans', 'Roboto', system-ui, -apple-system, sans-serif;
}

* { -webkit-tap-highlight-color: transparent; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--md-surface-dim);
  color: var(--md-on-surface);
  min-height: 100dvh;
  -webkit-font-smoothing: antialiased;
}

/* ─── App Shell ─────────────────────────────────────── */

.app-shell {
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  max-width: 100%;
}

.app-shell--center {
  justify-content: center;
  align-items: center;
  padding: 24px 20px;
}

.app-shell--wide {
  --app-max: 960px;
}

.app-content {
  flex: 1;
  width: 100%;
  max-width: var(--app-max);
  margin: 0 auto;
  padding: 16px 20px calc(var(--bottombar-h) + 24px);
}

.app-content--no-bottom {
  padding-bottom: 24px;
}

/* ─── Top App Bar ───────────────────────────────────── */

.app-topbar {
  position: sticky;
  top: 0;
  z-index: 40;
  height: var(--topbar-h);
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 0 8px 0 4px;
  background: color-mix(in srgb, var(--md-surface) 88%, transparent);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--md-outline-variant);
}

.app-topbar__title {
  flex: 1;
  min-width: 0;
}

.app-topbar__title h1 {
  margin: 0;
  font-size: 1.125rem;
  font-weight: 500;
  letter-spacing: 0.01em;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.app-topbar__title p {
  margin: 0;
  font-size: 0.75rem;
  color: var(--md-on-surface-variant);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.app-topbar__action {
  flex-shrink: 0;
}

/* ─── Hero / Login ──────────────────────────────────── */

.app-hero {
  text-align: center;
  margin-bottom: 32px;
}

.app-hero__icon {
  width: 72px;
  height: 72px;
  margin: 0 auto 16px;
  border-radius: var(--md-radius-lg);
  background: linear-gradient(135deg, var(--md-primary) 0%, #4285f4 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--md-elevation-2);
}

.app-hero__icon svg {
  width: 36px;
  height: 36px;
  fill: white;
}

.app-hero h1 {
  margin: 0 0 6px;
  font-size: 1.5rem;
  font-weight: 500;
}

.app-hero p {
  margin: 0;
  font-size: 0.875rem;
  color: var(--md-on-surface-variant);
  line-height: 1.5;
}

/* ─── Form Fields (Material filled) ─────────────────── */

.field {
  margin-bottom: 20px;
}

.field__label {
  display: block;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--md-on-surface-variant);
  margin-bottom: 6px;
  padding-left: 4px;
}

.field__input {
  width: 100%;
  box-sizing: border-box;
  padding: 16px 16px;
  font-size: 1rem;
  font-family: inherit;
  color: var(--md-on-surface);
  background: var(--md-surface-container);
  border: none;
  border-radius: var(--md-radius-sm);
  outline: none;
  transition: background 0.2s, box-shadow 0.2s;
}

.field__input:focus {
  background: var(--md-surface-container-high);
  box-shadow: 0 0 0 2px var(--md-primary-container), 0 0 0 3px var(--md-primary);
}

.field__input::placeholder {
  color: color-mix(in srgb, var(--md-on-surface-variant) 60%, transparent);
}

/* ─── Buttons ───────────────────────────────────────── */

.btn-md {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 24px;
  font-size: 0.9375rem;
  font-weight: 500;
  font-family: inherit;
  border: none;
  border-radius: var(--md-radius-full);
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.15s, opacity 0.15s;
  text-decoration: none;
  line-height: 1.2;
}

.btn-md:active { transform: scale(0.97); }

.btn-md--filled {
  background: var(--md-primary);
  color: var(--md-on-primary);
  box-shadow: var(--md-elevation-1);
}

.btn-md--filled:hover { box-shadow: var(--md-elevation-2); }

.btn-md--tonal {
  background: var(--md-primary-container);
  color: var(--md-primary);
}

.btn-md--text {
  background: transparent;
  color: var(--md-primary);
  padding: 10px 16px;
}

.btn-md--danger {
  background: var(--md-error);
  color: white;
}

.btn-md--success {
  background: var(--md-success-container);
  color: var(--md-success);
}

.btn-md--block { width: 100%; }

.btn-md:disabled,
.btn-md--disabled {
  opacity: 0.38;
  pointer-events: none;
  cursor: not-allowed;
}

.icon-btn {
  width: 40px;
  height: 40px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: none;
  background: transparent;
  border-radius: var(--md-radius-full);
  color: var(--md-on-surface);
  cursor: pointer;
  transition: background 0.15s;
}

.icon-btn:hover { background: var(--md-surface-container); }

/* ─── Sections & Lists (no boxes) ───────────────────── */

.section {
  margin-bottom: 28px;
}

.section__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
  padding: 0 4px;
}

.section__title {
  margin: 0;
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--md-on-surface-variant);
}

.list-surface {
  background: var(--md-surface);
  border-radius: var(--md-radius-md);
  overflow: hidden;
  box-shadow: var(--md-elevation-1);
}

.list-item {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 16px 20px;
  position: relative;
  transition: background 0.15s;
}

.list-item + .list-item::before {
  content: '';
  position: absolute;
  top: 0;
  left: 20px;
  right: 20px;
  height: 1px;
  background: var(--md-outline-variant);
}

.list-item--clickable { cursor: pointer; }
.list-item--clickable:active { background: var(--md-surface-container); }

.list-item__icon {
  width: 40px;
  height: 40px;
  border-radius: var(--md-radius-full);
  background: var(--md-primary-container);
  color: var(--md-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-size: 1.125rem;
}

.list-item__body { flex: 1; min-width: 0; }

.list-item__title {
  margin: 0 0 2px;
  font-size: 1rem;
  font-weight: 500;
}

.list-item__subtitle {
  margin: 0;
  font-size: 0.8125rem;
  color: var(--md-on-surface-variant);
  line-height: 1.4;
}

.list-item__meta { flex-shrink: 0; }

/* ─── Chips / Pills ─────────────────────────────────── */

.chip {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 6px 12px;
  font-size: 0.75rem;
  font-weight: 500;
  border-radius: var(--md-radius-full);
  white-space: nowrap;
}

.chip--primary { background: var(--md-primary-container); color: var(--md-primary); }
.chip--success { background: var(--md-success-container); color: var(--md-success); }
.chip--warning { background: var(--md-warning-container); color: #b06000; }
.chip--neutral { background: var(--md-surface-container); color: var(--md-on-surface-variant); }
.chip--timer { background: var(--md-warning-container); color: #b06000; font-variant-numeric: tabular-nums; font-size: 0.875rem; padding: 8px 14px; }
.chip--timer.urgent { background: var(--md-error-container); color: var(--md-error); }

/* ─── Exam cards (list style, not box) ──────────────── */

.exam-tile {
  padding: 20px;
  background: var(--md-surface);
  border-radius: var(--md-radius-md);
  box-shadow: var(--md-elevation-1);
  margin-bottom: 12px;
  transition: box-shadow 0.2s;
}

.exam-tile:active { box-shadow: var(--md-elevation-2); }

.exam-tile__head {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 12px;
  margin-bottom: 16px;
}

.exam-tile__title {
  margin: 0 0 4px;
  font-size: 1.0625rem;
  font-weight: 500;
}

.exam-tile__meta {
  margin: 0;
  font-size: 0.8125rem;
  color: var(--md-on-surface-variant);
}

/* ─── Question area ─────────────────────────────────── */

.question-panel {
  background: var(--md-surface);
  border-radius: var(--md-radius-md);
  padding: 24px 20px;
  box-shadow: var(--md-elevation-1);
  margin-bottom: 16px;
}

.question-panel__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
}

.question-panel__number {
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--md-primary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.question-panel__stem {
  font-size: 1.0625rem;
  line-height: 1.65;
  margin: 0 0 24px;
  color: var(--md-on-surface);
}

/* ─── Answer options (Android radio tiles) ──────────── */

.option-tile {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 16px 18px;
  margin-bottom: 10px;
  background: var(--md-surface-container);
  border-radius: var(--md-radius-sm);
  cursor: pointer;
  transition: background 0.15s, box-shadow 0.15s;
  border: 2px solid transparent;
}

.option-tile:last-child { margin-bottom: 0; }

.option-tile:hover { background: var(--md-surface-container-high); }

.option-tile--selected {
  background: var(--md-primary-container);
  border-color: var(--md-primary);
}

.option-tile__radio {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  border: 2px solid var(--md-on-surface-variant);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: border-color 0.15s;
}

.option-tile--selected .option-tile__radio {
  border-color: var(--md-primary);
}

.option-tile--selected .option-tile__radio::after {
  content: '';
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--md-primary);
}

.option-tile__label {
  flex: 1;
  font-size: 0.9375rem;
  line-height: 1.45;
}

.option-tile__key {
  font-weight: 500;
  color: var(--md-primary);
  margin-right: 6px;
}

.option-tile input { display: none; }

/* ─── Question nav grid ─────────────────────────────── */

.nav-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
}

.nav-pill {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8125rem;
  font-weight: 500;
  border: none;
  border-radius: var(--md-radius-full);
  background: var(--md-surface-container);
  color: var(--md-on-surface);
  cursor: pointer;
  transition: background 0.15s, transform 0.1s;
  font-family: inherit;
}

.nav-pill:active { transform: scale(0.92); }

.nav-pill--current { background: var(--md-primary); color: white; }
.nav-pill--answered { background: var(--md-success-container); color: var(--md-success); }
.nav-pill--flagged { background: var(--md-warning-container); color: #b06000; }

/* ─── Bottom bar (Android nav) ────────────────────────── */

.bottom-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 50;
  background: color-mix(in srgb, var(--md-surface) 92%, transparent);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-top: 1px solid var(--md-outline-variant);
  padding: 12px 20px calc(12px + env(safe-area-inset-bottom));
  display: flex;
  gap: 10px;
  align-items: center;
  justify-content: center;
}

.bottom-bar .btn-md { flex: 1; max-width: 160px; padding: 12px 16px; font-size: 0.875rem; }

/* ─── Bottom sheet modal ────────────────────────────── */

.sheet-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  z-index: 60;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s;
}

.sheet-backdrop.open {
  opacity: 1;
  pointer-events: auto;
}

.sheet {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 70;
  background: var(--md-surface);
  border-radius: var(--md-radius-lg) var(--md-radius-lg) 0 0;
  padding: 12px 24px calc(24px + env(safe-area-inset-bottom));
  transform: translateY(100%);
  transition: transform 0.3s cubic-bezier(0.32, 0.72, 0, 1);
  max-width: var(--app-max);
  margin: 0 auto;
}

.sheet.open { transform: translateY(0); }

.sheet__handle {
  width: 32px;
  height: 4px;
  background: var(--md-outline-variant);
  border-radius: var(--md-radius-full);
  margin: 0 auto 20px;
}

.sheet__title {
  margin: 0 0 8px;
  font-size: 1.25rem;
  font-weight: 500;
}

.sheet__text {
  margin: 0 0 24px;
  font-size: 0.9375rem;
  color: var(--md-on-surface-variant);
  line-height: 1.5;
}

.sheet__actions {
  display: flex;
  gap: 12px;
  justify-content: flex-end;
}

/* ─── Alerts / Toast style ──────────────────────────── */

.banner {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 14px 16px;
  border-radius: var(--md-radius-sm);
  font-size: 0.875rem;
  line-height: 1.45;
  margin-bottom: 20px;
}

.banner--error { background: var(--md-error-container); color: #93000a; }
.banner--success { background: var(--md-success-container); color: #0d652d; }
.banner--info { background: var(--md-primary-container); color: var(--md-primary); }

/* ─── Loading / Gate ────────────────────────────────── */

.gate-screen {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 48px 24px;
  min-height: 50dvh;
}

.gate-screen__spinner {
  width: 48px;
  height: 48px;
  border: 3px solid var(--md-primary-container);
  border-top-color: var(--md-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin-bottom: 24px;
}

@keyframes spin { to { transform: rotate(360deg); } }

.gate-screen h2 {
  margin: 0 0 8px;
  font-size: 1.125rem;
  font-weight: 500;
}

.gate-screen p {
  margin: 0;
  font-size: 0.875rem;
  color: var(--md-on-surface-variant);
  max-width: 280px;
}

/* ─── Nav drawer panel (exam sidebar → sheet on mobile) ─ */

.nav-panel {
  background: var(--md-surface);
  border-radius: var(--md-radius-md);
  padding: 20px;
  box-shadow: var(--md-elevation-1);
}

.nav-panel__title {
  margin: 0 0 16px;
  font-size: 0.8125rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--md-on-surface-variant);
}

/* ─── Desktop exam layout ───────────────────────────── */

@media (min-width: 768px) {
  :root { --app-max: 1100px; }

  .exam-layout {
    display: grid;
    grid-template-columns: 1fr 280px;
    gap: 20px;
    align-items: start;
  }

  .bottom-bar { position: sticky; border-radius: var(--md-radius-md); margin-top: 8px; }
  .app-shell--exam .app-content { padding-bottom: 24px; }
}

@media (max-width: 767px) {
  .nav-panel--desktop-only { display: none; }

  .fab-nav {
    position: fixed;
    bottom: calc(var(--bottombar-h) + 16px);
    right: 20px;
    z-index: 45;
    width: 56px;
    height: 56px;
    border-radius: var(--md-radius-lg);
    background: var(--md-primary);
    color: white;
    border: none;
    box-shadow: var(--md-elevation-3);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 1.25rem;
    transition: transform 0.15s;
  }

  .fab-nav:active { transform: scale(0.94); }
}

@media (min-width: 768px) {
  .fab-nav { display: none; }
}

.hidden { display: none !important; }

/* ─── Admin monitor ───────────────────────────────── */

.monitor-toolbar {
  display: flex;
  gap: 12px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.stat-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  margin-bottom: 24px;
}

@media (min-width: 768px) {
  .stat-grid { grid-template-columns: repeat(4, 1fr); }
}

.stat-card {
  background: var(--md-surface);
  border-radius: var(--md-radius-md);
  padding: 16px;
  box-shadow: var(--md-elevation-1);
}

.stat-card__label {
  display: block;
  font-size: 0.75rem;
  color: var(--md-on-surface-variant);
  margin-bottom: 6px;
}

.stat-card strong {
  font-size: 1.75rem;
  font-weight: 700;
  line-height: 1;
}

.stat-card__warn { color: var(--md-warning); }
.stat-card__info { color: var(--md-primary); }
.stat-card__ok { color: var(--md-success); }

.table-wrap {
  overflow-x: auto;
  background: var(--md-surface);
  border-radius: var(--md-radius-md);
  box-shadow: var(--md-elevation-1);
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.8125rem;
}

.data-table th,
.data-table td {
  padding: 10px 12px;
  text-align: left;
  border-bottom: 1px solid var(--md-outline-variant);
  vertical-align: middle;
}

.data-table th {
  background: var(--md-surface-container);
  color: var(--md-on-surface-variant);
  font-weight: 500;
  white-space: nowrap;
}

.data-table tbody tr:last-child td { border-bottom: none; }

.chip--info {
  background: var(--md-primary-container);
  color: var(--md-primary);
}

.chip--warn {
  background: var(--md-warning-container);
  color: #8a5700;
}

.exam-body--secure {
  -webkit-user-select: none;
  user-select: none;
}