/* === Global Design System === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --navy:   #1e3a5f;
  --blue:   #2563eb;
  --blue-h: #1d4ed8;
  --bg:     #f5f7fa;
  --white:  #ffffff;
  --border: #e5e7eb;
  --text:   #1a1a1a;
  --muted:  #6b7280;
  --radius: 10px;
  --shadow: 0 1px 4px rgba(0,0,0,0.08);
}

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

/* === Topbar === */
.topbar {
  background: var(--navy);
  color: #fff;
  height: 52px;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 100;
}
.topbar-title { font-weight: 700; font-size: 15px; letter-spacing: .2px; }
.topbar-nav { display: flex; align-items: center; gap: 20px; font-size: 13px; }
.topbar-nav a { color: #93c5fd; text-decoration: none; }
.topbar-nav a:hover { color: #fff; }
.topbar-user { color: #cbd5e1; font-size: 13px; }

/* === Page container === */
.page { max-width: 720px; margin: 32px auto; padding: 0 16px 80px; }
.page-wide { max-width: 960px; margin: 32px auto; padding: 0 16px 80px; }

/* === Card === */
.card {
  background: var(--white);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 16px;
  box-shadow: var(--shadow);
}
.card-title {
  font-size: 12px;
  font-weight: 700;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: .6px;
  margin-bottom: 16px;
}

/* === Forms === */
.form-group { margin-bottom: 14px; }
.form-group label { display: block; font-size: 13px; color: var(--muted); margin-bottom: 5px; font-weight: 500; }
.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 9px 12px;
  border: 1px solid var(--border);
  border-radius: 7px;
  font-size: 14px;
  font-family: inherit;
  background: #fff;
  color: var(--text);
  transition: border-color .15s;
}
.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus { outline: none; border-color: var(--blue); }

.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
@media (max-width: 480px) { .form-row { grid-template-columns: 1fr; } }

/* === Buttons === */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 10px 20px;
  border: none;
  border-radius: 7px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: opacity .15s, background .15s;
  text-decoration: none;
}
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn-primary  { background: var(--blue);  color: #fff; }
.btn-primary:hover  { background: var(--blue-h); }
.btn-navy    { background: var(--navy);  color: #fff; }
.btn-navy:hover    { background: #163050; }
.btn-ghost   { background: transparent; color: var(--muted); border: 1px solid var(--border); }
.btn-ghost:hover   { background: #f0f0f0; }
.btn-outline { background: transparent; color: var(--blue); border: 1.5px solid var(--blue); }
.btn-outline:hover:not(:disabled) { background: #eff6ff; }
.btn-outline:disabled { color: #9ca3af; border-color: #d1d5db; cursor: not-allowed; }
.btn-danger  { background: #ef4444; color: #fff; }
.btn-danger:hover  { background: #dc2626; }
.btn-full { width: 100%; }

/* === Question box (practice/exam) === */
.question-box {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px;
  margin-bottom: 14px;
  background: #fafafa;
}
.question-box.correct { border-left: 5px solid #22c55e; background: #f0fdf4; }
.question-box.wrong   { border-left: 5px solid #ef4444; background: #fef2f2; }

.question-image {
  max-width: 100%;
  max-height: 280px;
  object-fit: contain;
  display: block;
  margin: 10px auto;
  border-radius: 6px;
}

/* === Choice buttons === */
.choices { display: flex; flex-direction: column; gap: 8px; margin-top: 12px; }
.choice-btn {
  padding: 10px 14px;
  border: 1.5px solid var(--border);
  border-radius: 7px;
  background: #fff;
  text-align: left;
  font-size: 14px;
  cursor: pointer;
  transition: border-color .1s, background .1s;
}
.choice-btn:hover { border-color: var(--blue); background: #eff6ff; }
.choice-btn.selected { border-color: var(--blue); background: #dbeafe; font-weight: 600; }
.choice-btn.correct-ans { border-color: #22c55e; background: #dcfce7; }
.choice-btn.wrong-ans   { border-color: #ef4444; background: #fee2e2; }

/* === Exam layout (sidebar nav) === */
.exam-layout { display: flex; align-items: flex-start; gap: 20px; }
.question-area { flex: 1; min-width: 0; }
.nav-sidebar {
  width: 110px;
  flex-shrink: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
  position: sticky;
  top: 72px;
}
.nav-sidebar .btn { width: 100%; height: 72px; font-size: 24px; border: 2px solid var(--border); }
.nav-sidebar #prev-btn { color: #ef4444; border-color: #fca5a5; background: #fff5f5; }
.nav-sidebar #prev-btn:hover { background: #fee2e2; }

/* === Badge === */
.badge { display: inline-block; padding: 2px 9px; border-radius: 99px; font-size: 11px; font-weight: 700; }
.badge-success { background: #dcfce7; color: #166534; }
.badge-error   { background: #fee2e2; color: #b91c1c; }
.badge-info    { background: #dbeafe; color: #1e40af; }
.badge-warn    { background: #fef9c3; color: #854d0e; }

/* === Alert / message === */
.msg { padding: 10px 14px; border-radius: 7px; font-size: 14px; margin-top: 10px; display: none; }
.msg.show-success { display: block; background: #dcfce7; color: #166534; }
.msg.show-error   { display: block; background: #fee2e2; color: #b91c1c; }

/* === Table === */
.table { width: 100%; border-collapse: collapse; font-size: 13px; }
.table th { text-align: left; padding: 9px 12px; background: #f8fafc; color: var(--muted); font-weight: 600; border-bottom: 1px solid var(--border); }
.table td { padding: 9px 12px; border-bottom: 1px solid #f0f0f0; }
.table tr:last-child td { border-bottom: none; }
.table tr:hover td { background: #fafafa; }

/* === Utility === */
.hidden { display: none !important; }
.text-muted { color: var(--muted); }
.text-small { font-size: 12px; }
.mt-8  { margin-top: 8px; }
.mt-16 { margin-top: 16px; }
.flex  { display: flex; }
.items-center { align-items: center; }
.gap-8 { gap: 8px; }
.gap-16 { gap: 16px; }

/* === Responsive === */
@media (max-width: 600px) {
  .exam-layout { flex-direction: column-reverse; }
  .nav-sidebar { width: 100%; flex-direction: row; position: static; }
  .nav-sidebar .btn { height: 48px; flex: 1; font-size: 18px; }
}

@media print {
  .topbar, .nav-sidebar, .btn { display: none !important; }
  body { background: white; }
  .question-box { page-break-inside: avoid; break-inside: avoid; margin-bottom: 2rem; }
}