:root {
  --rv-primary: #0b3d91;
  --rv-primary-dark: #072a63;
  --rv-accent: #1e88e5;
  --rv-bg: #f4f7fb;
  --rv-card: #ffffff;
  --rv-border: #e3e8ef;
  --rv-text: #1f2937;
  --rv-muted: #6b7280;
  --rv-success: #198754;
  --rv-danger: #dc3545;
  --rv-warning: #f59e0b;
  --sidebar-width: 260px;
}

* { box-sizing: border-box; }

body {
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  background: var(--rv-bg);
  color: var(--rv-text);
  min-height: 100vh;
}

a { color: var(--rv-primary); text-decoration: none; }
a:hover { color: var(--rv-accent); }

.brand-logo {
  max-height: 52px;
  width: auto;
}

.brand-logo-sm { max-height: 40px; }

.powered-by {
  color: var(--rv-muted);
  font-size: 0.875rem;
}

.powered-by img {
  height: 22px;
  width: auto;
  vertical-align: middle;
  margin-left: 6px;
}

.auth-wrapper {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  background: linear-gradient(135deg, #e8f1ff 0%, #f8fafc 45%, #eef6ff 100%);
}

.auth-card {
  width: 100%;
  max-width: 440px;
  background: var(--rv-card);
  border: 1px solid var(--rv-border);
  border-radius: 16px;
  box-shadow: 0 10px 30px rgba(11, 61, 145, 0.08);
  padding: 2rem;
}

.auth-card .brand-block {
  text-align: center;
  margin-bottom: 1.5rem;
}

.auth-card h1 {
  font-size: 1.35rem;
  margin: 0.75rem 0 0.25rem;
  color: var(--rv-primary-dark);
}

.btn-rv {
  background: var(--rv-primary);
  border-color: var(--rv-primary);
  color: #fff;
}
.btn-rv:hover, .btn-rv:focus {
  background: var(--rv-primary-dark);
  border-color: var(--rv-primary-dark);
  color: #fff;
}

.card-soft {
  background: var(--rv-card);
  border: 1px solid var(--rv-border);
  border-radius: 14px;
  box-shadow: 0 4px 16px rgba(15, 23, 42, 0.04);
}

.stat-card {
  padding: 1.25rem;
  border-radius: 14px;
  border: 1px solid var(--rv-border);
  background: #fff;
  height: 100%;
}
.stat-card .stat-label {
  color: var(--rv-muted);
  font-size: 0.85rem;
  margin-bottom: 0.35rem;
}
.stat-card .stat-value {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--rv-primary-dark);
  line-height: 1.1;
}

.admin-shell {
  display: flex;
  min-height: 100vh;
}

.admin-sidebar {
  width: var(--sidebar-width);
  background: linear-gradient(180deg, var(--rv-primary-dark), #0a2f6f);
  color: #fff;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  flex-shrink: 0;
}

.admin-sidebar .sidebar-brand {
  padding: 1.25rem 1rem;
  border-bottom: 1px solid rgba(255,255,255,0.12);
  text-align: center;
}
.admin-sidebar .sidebar-brand img {
  max-height: 48px;
  filter: brightness(0) invert(1);
  background: #fff;
  border-radius: 8px;
  padding: 4px 8px;
}
.admin-sidebar .nav-link {
  color: rgba(255,255,255,0.85);
  padding: 0.7rem 1.1rem;
  border-radius: 8px;
  margin: 0.15rem 0.65rem;
}
.admin-sidebar .nav-link:hover,
.admin-sidebar .nav-link.active {
  background: rgba(255,255,255,0.12);
  color: #fff;
}

.admin-main {
  flex: 1;
  min-width: 0;
}

.admin-topbar, .student-topbar {
  background: #fff;
  border-bottom: 1px solid var(--rv-border);
  padding: 0.85rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.page-content { padding: 1.25rem; }

.student-nav {
  background: #fff;
  border-bottom: 1px solid var(--rv-border);
}
.student-nav .nav-link {
  color: var(--rv-text);
  font-weight: 500;
  padding: 0.9rem 1rem;
}
.student-nav .nav-link.active,
.student-nav .nav-link:hover {
  color: var(--rv-primary);
}

.timer-box {
  background: #fff5f5;
  border: 2px solid #fecaca;
  color: #991b1b;
  border-radius: 12px;
  padding: 0.55rem 1rem;
  font-weight: 700;
  font-size: 1.35rem;
  letter-spacing: 0.5px;
  min-width: 170px;
  text-align: center;
}
.timer-box.warning {
  background: #fff7ed;
  border-color: #fdba74;
  color: #9a3412;
  animation: pulse 1s infinite;
}
.timer-box.critical {
  background: #fef2f2;
  border-color: #f87171;
  color: #7f1d1d;
  animation: pulse 0.6s infinite;
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.03); }
}

.quiz-layout {
  display: grid;
  grid-template-columns: 1fr 280px;
  gap: 1rem;
}

.question-card {
  background: #fff;
  border: 1px solid var(--rv-border);
  border-radius: 14px;
  padding: 1.25rem;
}

.option-item {
  display: block;
  border: 1px solid var(--rv-border);
  border-radius: 10px;
  padding: 0.85rem 1rem;
  margin-bottom: 0.65rem;
  cursor: pointer;
  transition: all .15s ease;
  background: #fff;
}
.option-item:hover { border-color: var(--rv-accent); background: #f8fbff; }
.option-item.active {
  border-color: var(--rv-primary);
  background: #eef5ff;
  box-shadow: 0 0 0 2px rgba(11,61,145,0.12);
}
.option-item input { margin-right: 0.6rem; }

.qnav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}
.qnav-btn {
  width: 38px;
  height: 38px;
  border-radius: 8px;
  border: 1px solid var(--rv-border);
  background: #fff;
  color: var(--rv-text);
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.qnav-btn.current {
  border-color: var(--rv-primary);
  background: var(--rv-primary);
  color: #fff;
}
.qnav-btn.answered {
  border-color: #86efac;
  background: #dcfce7;
  color: #166534;
}
.qnav-btn.unanswered {
  background: #fff;
}

.result-banner {
  border-radius: 14px;
  padding: 1.5rem;
  color: #fff;
  text-align: center;
}
.result-banner.pass { background: linear-gradient(135deg, #15803d, #22c55e); }
.result-banner.fail { background: linear-gradient(135deg, #b91c1c, #ef4444); }

.table thead th {
  background: #f8fafc;
  white-space: nowrap;
}

.footer-bar {
  margin-top: auto;
  padding: 1rem 1.25rem;
  border-top: 1px solid var(--rv-border);
  background: #fff;
  text-align: center;
}

.quiz-navigator-card {
  position: sticky;
  top: 0.75rem;
}

.option-item {
  user-select: none;
  -webkit-user-select: none;
}

@media (max-width: 991.98px) {
  .admin-shell { flex-direction: column; }
  .admin-sidebar {
    width: 100%;
    height: auto;
    position: relative;
  }
  .quiz-layout {
    grid-template-columns: 1fr;
    display: flex;
    flex-direction: column-reverse;
    gap: 1rem;
  }
  .quiz-navigator-card {
    position: relative;
    top: 0;
  }
  .timer-box { font-size: 1.15rem; min-width: 140px; }
  .qnav-btn {
    width: 42px;
    height: 42px;
  }
}