:root {
  --bg: #f4f7ff;
  --panel: #ffffff;
  --primary: #4f46e5;
  --primary-soft: #eef2ff;
  --secondary: #7c3aed;
  --text: #1f2937;
  --muted: #6b7280;
  --border: #e5e7eb;
  --success: #10b981;
  --danger: #ef4444;
  --shadow: 0 12px 30px rgba(79, 70, 229, 0.12);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  background: linear-gradient(135deg, #eef4ff 0%, #f8f5ff 100%);
  color: var(--text);
}

.page-shell {
  max-width: 1100px;
  margin: 0 auto;
  padding: 40px 20px 60px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  margin-bottom: 28px;
}

.eyebrow {
  margin: 0;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: 12px;
}

h1 {
  margin: 8px 0 0;
  font-size: clamp(2rem, 3vw, 3rem);
  color: var(--primary);
}

.header-tag {
  background: rgba(79, 70, 229, 0.08);
  color: var(--primary);
  border: 1px solid rgba(79, 70, 229, 0.15);
  padding: 10px 16px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.92rem;
}

.dashboard {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 22px;
  box-shadow: var(--shadow);
  padding: 24px;
}

.task-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 16px;
  margin-top: 18px;
}

.task-card {
  border: 1px solid var(--border);
  background: #f9fafb;
  border-radius: 16px;
  padding: 16px 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  font-weight: 600;
  color: var(--text);
  cursor: pointer;
  transition: 0.2s ease;
}

.task-card:hover,
.task-card.active {
  background: linear-gradient(135deg, var(--primary-soft), #f3e8ff);
  border-color: rgba(79, 70, 229, 0.25);
  transform: translateY(-1px);
}

.task-icon {
  width: 32px;
  height: 32px;
  border-radius: 10px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: rgba(79, 70, 229, 0.12);
  color: var(--primary);
  font-weight: 700;
}

.label {
  display: inline-block;
  font-weight: 700;
  margin-bottom: 12px;
}

textarea {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 16px 18px;
  font: inherit;
  min-height: 160px;
  resize: vertical;
  background: #fbfbff;
  outline: none;
  transition: border 0.2s ease, box-shadow 0.2s ease;
}

textarea:focus {
  border-color: rgba(79, 70, 229, 0.6);
  box-shadow: 0 0 0 4px rgba(79, 70, 229, 0.08);
}

.primary-btn {
  margin-top: 18px;
  border: none;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: white;
  padding: 14px 20px;
  border-radius: 12px;
  font-weight: 700;
  cursor: pointer;
  width: 100%;
  transition: transform 0.2s ease;
}

.primary-btn:hover {
  transform: translateY(-1px);
}

.loading {
  margin-top: 16px;
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--primary);
  font-weight: 600;
}

.spinner {
  width: 18px;
  height: 18px;
  border: 3px solid rgba(79, 70, 229, 0.2);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

.error-box {
  margin-top: 16px;
  background: #fef2f2;
  border: 1px solid #fecaca;
  color: var(--danger);
  border-radius: 12px;
  padding: 12px 14px;
  font-weight: 600;
}

.result-area {
  min-height: 120px;
}

.card {
  background: #f8faff;
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 18px;
  margin-top: 12px;
}

.card h3,
.card h4 {
  margin-top: 0;
}

.answer-text,
.summary-text,
.explanation-text,
.learning-block,
.quiz-explanation {
  line-height: 1.7;
  white-space: pre-wrap;
}

.quiz-list {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.quiz-card {
  background: #f9f9ff;
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 18px;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-top: 12px;
}

.option-row {
  display: flex;
  align-items: center;
  gap: 10px;
  background: white;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 10px 12px;
}

.option-row input {
  accent-color: var(--primary);
}

.quiz-result {
  margin-top: 16px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
}

.score-badge {
  display: inline-block;
  background: rgba(16, 185, 129, 0.12);
  color: var(--success);
  padding: 8px 12px;
  border-radius: 999px;
  font-weight: 700;
  margin-top: 8px;
}

.correct {
  color: var(--success);
  font-weight: 700;
}

.wrong {
  color: var(--danger);
  font-weight: 700;
}

.hidden {
  display: none !important;
}

@media (max-width: 640px) {
  .topbar {
    flex-direction: column;
    align-items: flex-start;
  }

  .panel {
    padding: 18px;
  }
}