:root {
  --bg: #1a1a2e;
  --surface: #16213e;
  --surface2: #0f3460;
  --accent: #e94560;
  --accent-hover: #ff6b81;
  --success: #2ed573;
  --success-bg: rgba(46, 213, 115, 0.15);
  --warning: #ffa502;
  --warning-bg: rgba(255, 165, 2, 0.15);
  --danger: #ff4757;
  --danger-bg: rgba(255, 71, 87, 0.15);
  --text: #eee;
  --text-muted: #a0a0b0;
  --border: #2a2a4a;
  --radius: 10px;
  --radius-sm: 6px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

.katex, .katex * {
  box-sizing: content-box;
}

html, body {
  height: 100%;
  overflow: hidden;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.app {
  display: flex;
  flex-direction: column;
  height: 100%;
}

.header {
  background: var(--surface);
  padding: 14px 24px;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: baseline;
  gap: 10px;
}

.logo { font-size: 1.1rem; font-weight: 700; color: var(--accent); }
.subtitle { font-size: 0.75rem; color: var(--text-muted); flex: 1; }

.auth-area { display: flex; align-items: center; gap: 8px; }
.auth-user { font-size: 0.78rem; color: var(--text-muted); }

/* Auth Modal */
.modal-overlay {
  position: fixed; inset: 0;
  background: rgba(0,0,0,0.6);
  display: flex; align-items: center; justify-content: center;
  z-index: 100;
}
.modal-overlay.hidden { display: none; }
.modal-box {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 24px;
  max-width: 380px; width: 90%;
}
.modal-box h3 { font-size: 1rem; margin-bottom: 16px; }
.modal-box .form-group { margin-bottom: 12px; }
.modal-box .form-group label { display: block; font-size: 0.75rem; color: var(--text-muted); margin-bottom: 4px; }
.modal-box .form-group input {
  width: 100%; padding: 8px 12px; border-radius: var(--radius-sm);
  border: 1px solid var(--border); background: var(--bg); color: var(--text);
  font-size: 0.85rem; outline: none;
}
.modal-box .form-group input:focus { border-color: var(--accent); }
.modal-box .form-group.hidden { display: none; }
.modal-actions { display: flex; gap: 10px; margin-top: 16px; }
.modal-error { display: block; margin-top: 8px; font-size: 0.75rem; color: var(--danger); }
.modal-error.hidden { display: none; }
.auth-switch { margin-top: 12px; text-align: center; font-size: 0.78rem; }
.auth-switch a { color: var(--accent); text-decoration: none; }
.auth-switch a:hover { text-decoration: underline; }
.otp-message { font-size: 0.82rem; color: var(--text-muted); margin-bottom: 12px; line-height: 1.5; text-align: center; }

.main { flex: 1; display: flex; flex-direction: column; overflow: hidden; }

.footer {
  background: var(--surface);
  padding: 8px 24px;
  border-top: 1px solid var(--border);
  font-size: 0.7rem;
  color: var(--text-muted);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-shrink: 0;
}

#connection-status.offline { color: var(--danger); }
#connection-status.online { color: var(--success); }

.empty-state {
  display: flex;
  align-items: center;
  justify-content: center;
  flex: 1;
  color: var(--text-muted);
  font-size: 0.9rem;
  padding: 40px;
  text-align: center;
}

.hidden { display: none !important; }

.btn {
  padding: 10px 24px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
}
.btn:disabled { opacity: 0.4; cursor: not-allowed; }
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover:not(:disabled) { background: var(--accent-hover); }
.btn-outline { background: transparent; border: 1px solid var(--border); color: var(--text); }
.btn-outline:hover:not(:disabled) { background: var(--surface2); }
.btn-danger { background: transparent; border: 1px solid var(--danger); color: var(--danger); }
.btn-danger:hover:not(:disabled) { background: var(--danger); color: #fff; }

/* Paper Select */
.paper-select {
  padding: 32px 24px;
  max-width: 960px;
  margin: 0 auto;
  width: 100%;
}

.paper-select h2 {
  font-size: 1.1rem;
  margin-bottom: 24px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.paper-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 14px;
}

.paper-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  cursor: pointer;
  transition: border-color 0.2s, transform 0.15s;
}

.paper-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}

.paper-subject {
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text);
}

.paper-meta {
  display: flex;
  gap: 8px;
  margin-bottom: 10px;
  flex-wrap: wrap;
}

.paper-exam,
.paper-year,
.paper-type {
  font-size: 0.7rem;
  padding: 3px 8px;
  border-radius: 4px;
  font-weight: 500;
}

.paper-exam { background: var(--accent); color: #fff; }
.paper-year { background: var(--surface2); color: var(--text); }
.paper-type { background: var(--border); color: var(--text-muted); }

.paper-count {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Exam View */
.exam-view {
  display: flex;
  flex-direction: column;
  flex: 1;
  max-width: 800px;
  margin: 0 auto;
  width: 100%;
  padding: 16px 24px;
  overflow: hidden;
}

.exam-view.split-mode {
  max-width: none;
  padding: 12px 16px;
}

.exam-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 0;
  border-bottom: 1px solid var(--border);
  margin-bottom: 16px;
  flex-shrink: 0;
}

.exam-meta { display: flex; gap: 10px; align-items: center; }
.exam-subject { font-size: 0.9rem; font-weight: 600; }
.exam-badge {
  font-size: 0.7rem;
  padding: 3px 8px;
  border-radius: 4px;
  background: var(--accent);
  color: #fff;
}

.exam-timer {
  font-size: 1.3rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--warning);
}

.exam-body {
  display: flex;
  flex: 1;
  gap: 0;
  overflow: hidden;
  margin-bottom: 12px;
}

.question-panel {
  flex: 1;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  overflow-y: auto;
}

.question-panel.split-left {
  flex: 2;
  border-right: 1px solid var(--border);
  border-radius: var(--radius) 0 0 var(--radius);
  padding: 16px;
  overflow-y: auto;
}

.omr-panel {
  flex: 1;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 12px;
  overflow-y: auto;
  min-width: 260px;
  max-width: 340px;
}

.question-number {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-bottom: 14px;
}

.question-text {
  font-size: 1rem;
  line-height: 1.7;
  margin-bottom: 20px;
  white-space: pre-wrap;
  word-break: break-word;
}

.question-image {
  margin-bottom: 16px;
  text-align: center;
}

.question-image img {
  max-width: 100%;
  max-height: 300px;
  border-radius: var(--radius-sm);
  margin-bottom: 8px;
}

.passage-content {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 16px;
  margin-bottom: 14px;
  font-size: 0.9rem;
  line-height: 1.7;
  white-space: pre-wrap;
  max-height: 300px;
  overflow-y: auto;
}

.passage-content p {
  margin-bottom: 8px;
}

.passage-label {
  display: block;
  font-size: 0.7rem;
  font-weight: 700;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 8px;
}

.passage-section {
  border-color: var(--warning);
}

.passage-section .passage-label {
  color: var(--warning);
}

.passage-divider {
  border-top: 1px dashed var(--border);
  margin: 10px 0 14px 0;
}

.q-text {
  font-size: 0.95rem;
}

.passage-img {
  max-height: 250px;
}

.options-list {
  display: grid;
  gap: 10px;
}

.option-item {
  padding: 12px 16px;
  background: var(--bg);
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.15s;
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  gap: 10px;
}

.option-item:hover { border-color: var(--accent); }
.option-item.selected { border-color: var(--accent); background: rgba(233, 69, 96, 0.1); }

.option-letter {
  font-weight: 700;
  color: var(--accent);
  min-width: 24px;
}

/* Exam Nav */
.exam-nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  margin-bottom: 16px;
  flex-shrink: 0;
}

.exam-actions {
  display: flex;
  justify-content: space-between;
  padding-top: 8px;
  flex-shrink: 0;
}

.question-dots {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  justify-content: center;
  max-width: 400px;
}

.question-dot {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  border: 2px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.65rem;
  cursor: pointer;
  transition: all 0.15s;
  color: var(--text-muted);
}

.question-dot:hover { border-color: var(--accent); color: var(--text); }
.question-dot.active { border-color: var(--accent); background: var(--accent); color: #fff; }
.question-dot.answered { border-color: var(--success); background: var(--success-bg); color: var(--success); }
.question-dot.answered.active { background: var(--accent); color: #fff; border-color: var(--accent); }

.exam-actions {
  display: flex;
  justify-content: space-between;
  padding-top: 8px;
}

.btn-toggle {
  background: var(--surface2);
  color: var(--text-muted);
  border: 1px solid var(--border);
  padding: 4px 12px;
  font-size: 0.7rem;
  font-weight: 600;
  cursor: pointer;
  border-radius: var(--radius-sm);
  transition: all 0.15s;
}

.btn-toggle:hover {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.single-only.hidden {
  display: none;
}

/* Split View */
.split-passage {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  margin-bottom: 12px;
  font-size: 0.82rem;
  line-height: 1.6;
}

.split-passage .passage-label {
  display: block;
  font-size: 0.65rem;
  font-weight: 700;
  margin-bottom: 6px;
}

.split-passage-text {
  color: var(--text-muted);
  white-space: pre-wrap;
}

.split-question {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 12px;
  margin-bottom: 10px;
}

.split-q-header {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  margin-bottom: 8px;
}

.split-q-num {
  background: var(--surface2);
  color: var(--accent);
  font-weight: 700;
  font-size: 0.7rem;
  padding: 2px 8px;
  border-radius: 4px;
  flex-shrink: 0;
}

.split-q-num.answered {
  background: var(--success-bg);
  color: var(--success);
}

.split-q-text {
  font-size: 0.85rem;
  line-height: 1.5;
  flex: 1;
}

.split-options {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 6px;
}

.split-opt-btn {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 10px;
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text);
  font-size: 0.8rem;
  cursor: pointer;
  text-align: left;
  transition: all 0.12s;
  font-family: inherit;
}

.split-opt-btn:hover {
  border-color: var(--accent);
}

.split-opt-btn.selected {
  border-color: var(--accent);
  background: rgba(233, 69, 96, 0.15);
}

.opt-letter {
  font-weight: 700;
  color: var(--accent);
  min-width: 16px;
}

.split-img {
  max-width: 100%;
  max-height: 200px;
  border-radius: var(--radius-sm);
  margin: 6px 0;
  display: block;
}

/* OMR Sheet */
.omr-title {
  font-size: 0.7rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 10px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
  text-align: center;
}

.omr-grid {
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.omr-row {
  display: flex;
  align-items: center;
  gap: 5px;
  padding: 3px 4px;
  border-radius: 4px;
  transition: background 0.1s;
}

.omr-row.active {
  background: var(--surface2);
}

.omr-num {
  font-size: 0.68rem;
  font-weight: 600;
  color: var(--text-muted);
  min-width: 28px;
  text-align: right;
  cursor: pointer;
  user-select: none;
}

.omr-num:hover {
  color: var(--text);
}

.omr-bubble {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  border: 2px solid var(--border);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 0.65rem;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.12s;
  color: var(--text-muted);
  user-select: none;
}

.omr-bubble:hover:not(.empty) {
  border-color: var(--accent);
  color: var(--text);
}

.omr-bubble.selected {
  border-color: var(--success);
  background: var(--success-bg);
  color: var(--success);
}

.omr-bubble.empty {
  border-color: transparent;
  cursor: default;
  opacity: 0;
}

@media (max-width: 700px) {
  .results-summary { grid-template-columns: repeat(3, 1fr); }
  .review-answers { grid-template-columns: 1fr; }
  .paper-grid { grid-template-columns: 1fr; }
  .exam-view { padding: 12px; }
  .question-panel { padding: 16px; }
}

/* Dashboard */
.dashboard-view {
  padding: 24px;
  max-width: 800px;
  margin: 0 auto;
  width: 100%;
  overflow-y: auto;
}
.dashboard-view h2 { font-size: 1.1rem; margin-bottom: 4px; }
.dashboard-sub { font-size: 0.8rem; color: var(--text-muted); margin-bottom: 20px; }
.dash-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  margin-bottom: 14px;
}
.dash-header {
  display: flex; justify-content: space-between; align-items: center;
  margin-bottom: 12px;
}
.dash-subject { font-weight: 600; font-size: 0.95rem; }
.dash-exam { font-size: 0.7rem; background: var(--accent); color: #fff; padding: 2px 8px; border-radius: 4px; }
.dash-stats { display: flex; gap: 20px; margin-bottom: 12px; }
.dash-stat { text-align: center; }
.dash-value { font-size: 1.3rem; font-weight: 700; display: block; }
.dash-label { font-size: 0.65rem; color: var(--text-muted); text-transform: uppercase; }
.dash-topics { margin-bottom: 8px; }
.dash-topic-label { font-size: 0.7rem; color: var(--text-muted); margin-right: 6px; }
.tag {
  display: inline-block; font-size: 0.68rem; padding: 2px 8px;
  border-radius: 4px; margin-right: 4px; margin-bottom: 4px;
}
.tag.strength { background: var(--success-bg); color: var(--success); }
.tag.weakness { background: var(--danger-bg); color: var(--danger); }
.dash-chart {
  display: flex; align-items: flex-end; gap: 4px;
  height: 80px; padding: 4px 0;
}
.chart-bar {
  flex: 1; min-width: 12px; background: var(--accent);
  border-radius: 2px 2px 0 0;
  transition: height 0.3s;
}
  .question-panel.split-left {
    border-radius: var(--radius) var(--radius) 0 0;
    flex: none;
    max-height: 50vh;
  }
  .omr-panel {
    border-radius: 0 0 var(--radius) var(--radius);
    max-width: none;
    flex: none;
  }
  .omr-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    gap: 2px;
  }
  .omr-num {
    min-width: 20px;
  }
}

/* Results View */
.results-view {
  padding: 32px 24px;
  max-width: 800px;
  margin: 0 auto;
  width: 100%;
}

.results-view h2 {
  font-size: 1.2rem;
  margin-bottom: 24px;
  text-align: center;
}

.results-summary {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 12px;
  margin-bottom: 24px;
}

.result-stat {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  text-align: center;
}

.stat-value {
  display: block;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--accent);
}

#result-correct + .stat-label { color: var(--success); }
#result-wrong + .stat-label { color: var(--danger); }

.stat-label {
  font-size: 0.7rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.review-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 24px;
  max-height: 50vh;
  overflow-y: auto;
}

.review-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px;
}

.review-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 8px;
}

.review-number { font-weight: 600; font-size: 0.85rem; }
.review-topic {
  font-size: 0.7rem;
  padding: 2px 8px;
  border-radius: 4px;
  background: var(--surface2);
  color: var(--text-muted);
  margin: 0 auto 0 10px;
}
.review-status { font-size: 0.75rem; font-weight: 600; }
.review-status.correct { color: var(--success); }
.review-status.wrong { color: var(--danger); }
.review-status.unanswered { color: var(--warning); }

.review-question {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 8px;
  line-height: 1.5;
}

.review-answers {
  font-size: 0.8rem;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4px;
}

.review-answer {
  padding: 4px 8px;
  border-radius: 4px;
}

.review-answer.chosen {
  background: var(--danger-bg);
  color: var(--danger);
}

.review-answer.correct-answer {
  background: var(--success-bg);
  color: var(--success);
}

.review-explanation {
  margin-top: 8px;
  padding: 8px 10px;
  background: var(--surface2);
  border-left: 3px solid var(--accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-size: 0.78rem;
  line-height: 1.5;
  color: var(--text-muted);
  grid-column: 1 / -1;
}

.results-note {
  text-align: center;
  padding: 10px;
  margin-bottom: 16px;
  background: var(--warning-bg);
  border: 1px solid var(--warning);
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  color: var(--warning);
}

.results-actions {
  display: flex;
  justify-content: center;
  gap: 12px;
}

@media (max-width: 600px) {
  .results-summary { grid-template-columns: repeat(3, 1fr); }
  .review-answers { grid-template-columns: 1fr; }
  .paper-grid { grid-template-columns: 1fr; }
  .exam-view { padding: 12px; }
  .question-panel { padding: 16px; }
}