/* Modern Design System & CSS Variables */
:root {
  --bg-primary: #0b0f19;
  --bg-secondary: #111827;
  --bg-card: rgba(17, 24, 39, 0.75);
  --bg-card-hover: rgba(31, 41, 55, 0.85);
  --bg-modal: #1f2937;
  
  --border-color: rgba(255, 255, 255, 0.08);
  --border-glow: rgba(59, 130, 246, 0.4);

  --text-primary: #f9fafb;
  --text-secondary: #9ca3af;
  --text-muted: #6b7280;

  --accent-primary: #3b82f6;
  --accent-primary-hover: #2563eb;
  --accent-glow: rgba(59, 130, 246, 0.25);
  
  --success: #10b981;
  --success-bg: rgba(16, 185, 129, 0.12);
  --success-border: rgba(16, 185, 129, 0.3);

  --danger: #ef4444;
  --danger-bg: rgba(239, 68, 68, 0.12);
  --danger-border: rgba(239, 68, 68, 0.3);

  --warning: #f59e0b;
  --warning-bg: rgba(245, 158, 11, 0.12);

  --purple: #8b5cf6;
  
  --font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;

  --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.2);
  --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.5), 0 8px 10px -6px rgba(0, 0, 0, 0.4);
  --shadow-glow: 0 0 25px rgba(59, 130, 246, 0.3);
}

/* Reset & Global Base */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-family);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  line-height: 1.6;
  overflow-x: hidden;
  background-image: 
    radial-gradient(at 10% 10%, rgba(59, 130, 246, 0.08) 0px, transparent 50%),
    radial-gradient(at 90% 90%, rgba(139, 92, 246, 0.08) 0px, transparent 50%);
}

/* Layout Utilities */
.container {
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 24px;
  width: 100%;
}

.hidden {
  display: none !important;
}

/* Navigation Header */
.app-header {
  background: rgba(11, 15, 25, 0.85);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
  padding: 16px 0;
}

.header-wrapper {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  cursor: pointer;
}

.logo-icon {
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, var(--accent-primary), var(--purple));
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  color: white;
  box-shadow: 0 4px 12px rgba(59, 130, 246, 0.4);
}

.brand-title span {
  background: linear-gradient(90deg, #60a5fa, #c084fc);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.admin-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(239, 68, 68, 0.15);
  color: #f87171;
  border: 1px solid rgba(239, 68, 68, 0.3);
  padding: 4px 12px;
  border-radius: var(--radius-full);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.03em;
}

.admin-login-card {
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
}

.form-group {
  margin-bottom: 16px;
}

.form-label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 6px;
}

.form-input {
  width: 100%;
  padding: 10px 14px;
  background: rgba(0, 0, 0, 0.3);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-size: 0.95rem;
  outline: none;
  font-family: inherit;
  transition: border-color 0.2s;
}

.form-input:focus {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.auth-error-msg {
  color: #f87171;
  font-size: 0.85rem;
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 6px;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  font-size: 0.95rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  text-decoration: none;
  font-family: inherit;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent-primary), #2563eb);
  color: white;
  box-shadow: 0 4px 14px rgba(59, 130, 246, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(59, 130, 246, 0.5);
  background: linear-gradient(135deg, #2563eb, #1d4ed8);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.05);
  border-color: var(--border-color);
  color: var(--text-primary);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.2);
}

.btn-success {
  background: linear-gradient(135deg, #10b981, #059669);
  color: white;
  box-shadow: 0 4px 14px rgba(16, 185, 129, 0.3);
}

.btn-success:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(16, 185, 129, 0.5);
}

.btn-outline-danger {
  background: transparent;
  border-color: var(--danger-border);
  color: var(--danger);
}

.btn-outline-danger:hover {
  background: var(--danger-bg);
}

/* Banner Hero */
.hero-section {
  padding: 48px 0 32px;
  text-align: center;
}

.hero-title {
  font-size: 2.75rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
}

.hero-title .gradient-text {
  background: linear-gradient(135deg, #3b82f6 0%, #a855f7 50%, #ec4899 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  color: var(--text-secondary);
  font-size: 1.15rem;
  max-width: 680px;
  margin: 0 auto 32px;
}

/* Stats Overview Cards */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
  margin-bottom: 40px;
}

.stat-card {
  background: var(--bg-card);
  backdrop-filter: blur(12px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 20px;
  display: flex;
  align-items: center;
  gap: 16px;
  transition: transform 0.2s ease;
}

.stat-card:hover {
  transform: translateY(-4px);
  border-color: rgba(255, 255, 255, 0.15);
}

.stat-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
}

.stat-icon.blue { background: rgba(59, 130, 246, 0.15); color: #60a5fa; }
.stat-icon.green { background: rgba(16, 185, 129, 0.15); color: #34d399; }
.stat-icon.purple { background: rgba(139, 92, 246, 0.15); color: #a78bfa; }
.stat-icon.amber { background: rgba(245, 158, 11, 0.15); color: #fbbf24; }

.stat-value {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
}

.stat-label {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

/* Filter Controls */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  margin-bottom: 28px;
  background: var(--bg-card);
  padding: 16px 20px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
}

.search-box {
  position: relative;
  flex: 1;
  min-width: 260px;
}

.search-box i {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
}

.search-input {
  width: 100%;
  padding: 10px 14px 10px 42px;
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-size: 0.95rem;
  font-family: inherit;
  outline: none;
  transition: border-color 0.2s;
}

.search-input:focus {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.category-pills {
  display: flex;
  gap: 8px;
  overflow-x: auto;
}

.pill {
  padding: 8px 16px;
  font-size: 0.85rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  cursor: pointer;
  white-space: nowrap;
  transition: all 0.2s;
}

.pill.active, .pill:hover {
  background: var(--accent-primary);
  color: white;
  border-color: var(--accent-primary);
}

/* Exam Grid */
.exams-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 24px;
  margin-bottom: 60px;
}

.exam-card {
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  position: relative;
  overflow: hidden;
  transition: all 0.3s ease;
}

.exam-card:hover {
  transform: translateY(-6px);
  border-color: rgba(255, 255, 255, 0.2);
  box-shadow: var(--shadow-lg);
}

.exam-badge {
  align-self: flex-start;
  padding: 4px 12px;
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 16px;
}

.exam-header-row {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 12px;
}

.exam-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  background: rgba(255, 255, 255, 0.06);
}

.exam-title {
  font-size: 1.15rem;
  font-weight: 700;
  line-height: 1.3;
}

.exam-desc {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: 20px;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.exam-meta-row {
  display: flex;
  gap: 16px;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 24px;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  padding-top: 14px;
}

.exam-meta-item {
  display: flex;
  align-items: center;
  gap: 6px;
}

.exam-actions {
  display: flex;
  gap: 10px;
}

.exam-actions .btn {
  flex: 1;
}

/* Modal Styling */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.75);
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: 20px;
  animation: fadeIn 0.2s ease;
}

.modal-content {
  background: var(--bg-modal);
  border: 1px solid rgba(255, 255, 255, 0.15);
  border-radius: var(--radius-lg);
  width: 100%;
  max-width: 600px;
  box-shadow: var(--shadow-lg);
  overflow: hidden;
}

.modal-header {
  padding: 20px 24px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.modal-title {
  font-size: 1.2rem;
  font-weight: 700;
}

.close-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 1.3rem;
  cursor: pointer;
  padding: 4px;
  transition: color 0.2s;
}

.close-btn:hover {
  color: var(--text-primary);
}

.modal-body {
  padding: 24px;
}

/* Upload Dropzone */
.dropzone {
  border: 2px dashed rgba(255, 255, 255, 0.2);
  border-radius: var(--radius-md);
  padding: 36px 20px;
  text-align: center;
  background: rgba(0, 0, 0, 0.2);
  cursor: pointer;
  transition: all 0.2s ease;
  margin-bottom: 20px;
}

.dropzone:hover, .dropzone.dragover {
  border-color: var(--accent-primary);
  background: var(--accent-glow);
}

.dropzone-icon {
  font-size: 2.5rem;
  color: var(--accent-primary);
  margin-bottom: 12px;
}

.dropzone-text {
  font-weight: 600;
  margin-bottom: 6px;
}

.dropzone-subtext {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.template-download-box {
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 14px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

/* Quiz Interface Layout */
.quiz-wrapper {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 28px;
  padding-top: 24px;
}

@media (max-width: 900px) {
  .quiz-wrapper {
    grid-template-columns: 1fr;
  }
}

.quiz-main-card {
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 32px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  min-height: 520px;
}

.quiz-top-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border-color);
}

.question-counter {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--accent-primary);
}

.timer-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(239, 68, 68, 0.15);
  color: #f87171;
  border: 1px solid rgba(239, 68, 68, 0.3);
  padding: 6px 14px;
  border-radius: var(--radius-full);
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.9rem;
}

.flag-btn {
  background: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  transition: all 0.2s;
}

.flag-btn.flagged {
  background: var(--warning-bg);
  color: var(--warning);
  border-color: var(--warning);
}

.question-title {
  font-size: 1.25rem;
  font-weight: 600;
  line-height: 1.5;
  margin-bottom: 28px;
}

.options-list {
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-bottom: 32px;
}

.option-item {
  background: rgba(255, 255, 255, 0.03);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 16px 20px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 14px;
  transition: all 0.2s ease;
}

.option-item:hover {
  background: rgba(255, 255, 255, 0.07);
  border-color: rgba(255, 255, 255, 0.2);
}

.option-item.selected {
  background: rgba(59, 130, 246, 0.12);
  border-color: var(--accent-primary);
  box-shadow: 0 0 15px var(--accent-glow);
}

.option-prefix {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.08);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.85rem;
  color: var(--text-secondary);
  flex-shrink: 0;
}

.option-item.selected .option-prefix {
  background: var(--accent-primary);
  color: white;
}

.option-text {
  font-size: 0.98rem;
  color: var(--text-primary);
}

/* Quiz Controls */
.quiz-controls {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 20px;
  border-top: 1px solid var(--border-color);
}

/* Palette Sidebar */
.quiz-sidebar {
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
  display: flex;
  flex-direction: column;
}

.sidebar-title {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.palette-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 10px;
  margin-bottom: 24px;
}

.palette-item {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 0.85rem;
  color: var(--text-secondary);
  cursor: pointer;
  position: relative;
  transition: all 0.2s;
}

.palette-item:hover {
  border-color: rgba(255, 255, 255, 0.3);
}

.palette-item.active {
  border-color: var(--accent-primary);
  box-shadow: 0 0 10px var(--accent-glow);
  font-weight: 800;
}

.palette-item.answered {
  background: var(--accent-primary);
  color: white;
  border-color: var(--accent-primary);
}

.palette-item.flagged::after {
  content: '';
  position: absolute;
  top: 2px;
  right: 2px;
  width: 8px;
  height: 8px;
  background: var(--warning);
  border-radius: 50%;
}

.legend-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
  font-size: 0.8rem;
  color: var(--text-secondary);
  border-top: 1px solid var(--border-color);
  padding-top: 16px;
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 8px;
}

.legend-dot {
  width: 12px;
  height: 12px;
  border-radius: 3px;
}

/* Results Screen */
.results-container {
  padding: 32px 0 60px;
}

.score-banner {
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 40px;
  text-align: center;
  margin-bottom: 40px;
  box-shadow: var(--shadow-lg);
}

.score-circle {
  width: 130px;
  height: 130px;
  border-radius: 50%;
  margin: 0 auto 24px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  border: 6px solid var(--accent-primary);
  box-shadow: var(--shadow-glow);
}

.score-circle.pass {
  border-color: var(--success);
  box-shadow: 0 0 30px rgba(16, 185, 129, 0.4);
}

.score-circle.fail {
  border-color: var(--danger);
  box-shadow: 0 0 30px rgba(239, 68, 68, 0.4);
}

.score-percent {
  font-size: 2.2rem;
  line-height: 1;
}

.score-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
}

.result-status-title {
  font-size: 1.8rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.result-status-sub {
  color: var(--text-secondary);
  margin-bottom: 32px;
}

.results-stats-row {
  display: flex;
  justify-content: center;
  gap: 32px;
  flex-wrap: wrap;
}

.result-stat-box {
  text-align: center;
}

.result-stat-num {
  font-size: 1.4rem;
  font-weight: 700;
}

.result-stat-text {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* Question Breakdown Review List */
.review-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
}

.review-filter-tabs {
  display: flex;
  gap: 8px;
}

.review-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
  margin-bottom: 20px;
  transition: border-color 0.2s;
}

.review-card.correct {
  border-left: 5px solid var(--success);
}

.review-card.incorrect {
  border-left: 5px solid var(--danger);
}

.review-card.unanswered {
  border-left: 5px solid var(--warning);
}

.review-q-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
  margin-bottom: 16px;
}

.review-q-title {
  font-size: 1.05rem;
  font-weight: 600;
}

.review-options-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 16px;
}

.review-option-item {
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border-color);
  font-size: 0.92rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.review-option-item.correct-choice {
  background: var(--success-bg);
  border-color: var(--success-border);
  color: #6ee7b7;
  font-weight: 600;
}

.review-option-item.user-wrong-choice {
  background: var(--danger-bg);
  border-color: var(--danger-border);
  color: #fca5a5;
}

.explanation-box {
  background: rgba(59, 130, 246, 0.08);
  border: 1px solid rgba(59, 130, 246, 0.2);
  border-radius: var(--radius-sm);
  padding: 14px 18px;
  font-size: 0.9rem;
  color: #93c5fd;
  display: flex;
  gap: 12px;
  align-items: flex-start;
}

.explanation-box i {
  margin-top: 3px;
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 2000;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.toast {
  background: var(--bg-modal);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 14px 20px;
  color: var(--text-primary);
  box-shadow: var(--shadow-lg);
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.9rem;
  animation: slideInRight 0.3s ease;
}

.toast.success { border-left: 4px solid var(--success); }
.toast.error { border-left: 4px solid var(--danger); }

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideInRight {
  from { transform: translateX(100%); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}