:root {
  --bg: #f6f8fc;
  --surface: #ffffff;
  --surface-soft: #f1f5f9;
  --text: #1e293b;
  --text-muted: #64748b;
  --border: #e2e8f0;

  --primary: #4f46e5;
  --primary-soft: #eef2ff;
  --primary-dark: #3730a3;

  --math: #2563eb;
  --math-soft: #eff6ff;
  --van: #e11d48;
  --van-soft: #fff1f2;
  --eng: #7c3aed;
  --eng-soft: #f5f3ff;
  --chem: #059669;
  --chem-soft: #ecfdf5;

  --success: #16a34a;
  --success-soft: #dcfce7;
  --danger: #dc2626;
  --danger-soft: #fee2e2;
  --warning: #d97706;
  --warning-soft: #fef3c7;

  --radius: 16px;
  --radius-sm: 10px;
  --shadow: 0 4px 20px rgba(15, 23, 42, 0.06);
  --shadow-hover: 0 10px 28px rgba(15, 23, 42, 0.1);
}

body.grade-7 {
  --primary: #0d9488;
  --primary-soft: #f0fdfa;
  --primary-dark: #115e59;
}

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

body {
  font-family: "Be Vietnam Pro", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.container {
  width: 100%;
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 20px;
}

.hidden {
  display: none !important;
}

/* ===== Topbar ===== */
.topbar {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 50;
}

.topbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  min-height: 72px;
  padding-top: 10px;
  padding-bottom: 10px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: inherit;
}

.brand-logo {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  background: var(--primary-soft);
  display: grid;
  place-items: center;
  font-size: 24px;
}

.brand-text {
  display: flex;
  flex-direction: column;
}

.brand-name {
  font-weight: 800;
  font-size: 1.15rem;
  color: var(--text);
  line-height: 1.2;
}

.brand-sub {
  font-size: 0.78rem;
  color: var(--text-muted);
}

.grade-switcher {
  display: flex;
  background: var(--surface-soft);
  padding: 4px;
  border-radius: 14px;
  gap: 4px;
}

.grade-btn {
  border: none;
  background: transparent;
  padding: 8px 16px;
  border-radius: 10px;
  font-family: inherit;
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--text-muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: all 0.2s ease;
}

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

.grade-btn.active {
  background: var(--surface);
  color: var(--primary);
  box-shadow: 0 2px 8px rgba(15, 23, 42, 0.08);
}

/* ===== Main ===== */
.main-content {
  flex: 1;
  padding-top: 28px;
  padding-bottom: 56px;
}

/* ===== Hero ===== */
.hero-card {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: #ffffff;
  border-radius: 22px;
  padding: 28px 32px;
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: 28px;
  align-items: center;
  box-shadow: 0 12px 30px rgba(79, 70, 229, 0.18);
  margin-bottom: 28px;
}

body.grade-7 .hero-card {
  box-shadow: 0 12px 30px rgba(13, 148, 136, 0.18);
}

.hero-badge {
  display: inline-block;
  background: rgba(255, 255, 255, 0.2);
  padding: 4px 12px;
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 700;
  margin-bottom: 10px;
}

.hero-title {
  font-size: 1.75rem;
  font-weight: 800;
  line-height: 1.3;
  margin-bottom: 8px;
}

.hero-desc {
  font-size: 0.96rem;
  opacity: 0.92;
}

.progress-box {
  background: rgba(255, 255, 255, 0.14);
  backdrop-filter: blur(8px);
  border: 1px solid rgba(255, 255, 255, 0.22);
  border-radius: 16px;
  padding: 18px 20px;
}

.progress-header {
  display: flex;
  justify-content: space-between;
  font-size: 0.9rem;
  margin-bottom: 10px;
}

.progress-track {
  height: 10px;
  background: rgba(255, 255, 255, 0.25);
  border-radius: 999px;
  overflow: hidden;
  margin-bottom: 10px;
}

.progress-fill {
  height: 100%;
  background: #fde047;
  border-radius: 999px;
  transition: width 0.4s ease;
}

.progress-stats {
  display: flex;
  justify-content: space-between;
  font-size: 0.82rem;
  opacity: 0.95;
  font-weight: 600;
}

/* ===== Toolbar ===== */
.toolbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  margin-bottom: 24px;
}

.subject-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.pill-btn {
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  padding: 8px 16px;
  border-radius: 999px;
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: all 0.18s ease;
}

.pill-btn:hover {
  border-color: var(--primary);
  transform: translateY(-1px);
}

.pill-btn.active {
  background: var(--primary);
  color: #ffffff;
  border-color: var(--primary);
}

.search-box {
  position: relative;
  min-width: 260px;
  flex: 1;
  max-width: 340px;
}

.search-icon {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 0.95rem;
  pointer-events: none;
}

.search-box input {
  width: 100%;
  padding: 10px 14px 10px 40px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--surface);
  font-family: inherit;
  font-size: 0.9rem;
  color: var(--text);
  outline: none;
  transition: border-color 0.2s;
}

.search-box input:focus {
  border-color: var(--primary);
}

.status-filter-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-top: -10px;
  margin-bottom: 20px;
}

.status-filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.btn-random-quiz {
  border: none;
  background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
  color: #ffffff;
  padding: 8px 16px;
  border-radius: 12px;
  font-family: inherit;
  font-size: 0.88rem;
  font-weight: 700;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  box-shadow: 0 4px 12px rgba(217, 119, 6, 0.22);
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.btn-random-quiz:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(217, 119, 6, 0.3);
}

.status-pill {
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text-muted);
  padding: 6px 14px;
  border-radius: 10px;
  font-family: inherit;
  font-size: 0.84rem;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.15s ease;
}

.status-pill:hover {
  border-color: var(--primary);
  color: var(--text);
}

.status-pill.active {
  background: var(--primary-soft);
  color: var(--primary-dark);
  border-color: var(--primary);
}

.all-done-banner {
  background: var(--success-soft);
  border: 1px solid #86efac;
  color: #14532d;
  border-radius: var(--radius);
  padding: 16px 20px;
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 20px;
}

.all-done-icon {
  font-size: 2rem;
  flex-shrink: 0;
}

.all-done-banner p {
  font-size: 0.88rem;
  margin-top: 2px;
}

.lesson-card.is-done {
  border-color: #bbf7d0;
  background: linear-gradient(180deg, #ffffff 0%, #f0fdf4 100%);
}

/* ===== Lessons Grid ===== */
.lessons-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(310px, 1fr));
  gap: 20px;
}

.lesson-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
  box-shadow: var(--shadow);
  position: relative;
}

.lesson-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
  border-color: var(--primary);
}

.lesson-card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.subject-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 12px;
  border-radius: 999px;
  font-size: 0.78rem;
  font-weight: 700;
}

.subject-tag.math { background: var(--math-soft); color: var(--math); }
.subject-tag.van { background: var(--van-soft); color: var(--van); }
.subject-tag.eng { background: var(--eng-soft); color: var(--eng); }
.subject-tag.chem { background: var(--chem-soft); color: var(--chem); }

.status-badge {
  font-size: 0.78rem;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--surface-soft);
  color: var(--text-muted);
}

.status-badge.done {
  background: var(--success-soft);
  color: var(--success);
}

.lesson-card h3 {
  font-size: 1.12rem;
  font-weight: 700;
  color: var(--text);
  line-height: 1.4;
}

.lesson-card p {
  font-size: 0.9rem;
  color: var(--text-muted);
  flex: 1;
}

.lesson-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 12px;
  border-top: 1px solid var(--border);
  font-size: 0.84rem;
  font-weight: 600;
  color: var(--primary);
}

.empty-state {
  text-align: center;
  padding: 56px 20px;
  background: var(--surface);
  border-radius: var(--radius);
  border: 1px dashed var(--border);
}

.empty-icon {
  font-size: 2.5rem;
  margin-bottom: 10px;
}

/* ===== Lesson Detail View ===== */
.lesson-topbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 18px;
}

.btn-back {
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  padding: 9px 16px;
  border-radius: var(--radius-sm);
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s;
}

.btn-back:hover {
  background: var(--surface-soft);
  border-color: var(--primary);
}

.lesson-meta-badges {
  display: flex;
  gap: 8px;
  align-items: center;
}

.lesson-shell {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 22px;
  box-shadow: var(--shadow);
  overflow: hidden;
}

.lesson-header {
  padding: 28px 32px 20px;
  border-bottom: 1px solid var(--border);
  background: linear-gradient(180deg, var(--primary-soft) 0%, rgba(255, 255, 255, 0) 100%);
}

.lesson-title {
  font-size: 1.6rem;
  font-weight: 800;
  margin-bottom: 6px;
}

.lesson-subtitle {
  color: var(--text-muted);
  font-size: 0.98rem;
}

.lesson-tabs {
  display: flex;
  gap: 4px;
  padding: 12px 32px 0;
  border-bottom: 1px solid var(--border);
  background: var(--surface);
  overflow-x: auto;
}

.tab-btn {
  border: none;
  background: transparent;
  padding: 12px 18px;
  font-family: inherit;
  font-size: 0.94rem;
  font-weight: 700;
  color: var(--text-muted);
  cursor: pointer;
  border-bottom: 3px solid transparent;
  white-space: nowrap;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  transition: all 0.15s;
}

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

.tab-btn.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
}

.tab-count {
  background: var(--primary-soft);
  color: var(--primary);
  padding: 2px 8px;
  border-radius: 999px;
  font-size: 0.78rem;
}

.tab-panel {
  display: none;
  padding: 28px 32px 34px;
}

.tab-panel.active {
  display: block;
}

/* ===== Visual Learning Blocks ===== */
.learn-content {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.concept-card {
  background: var(--surface-soft);
  border-radius: var(--radius);
  padding: 20px 24px;
  border-left: 5px solid var(--primary);
}

.concept-card h3 {
  font-size: 1.08rem;
  font-weight: 700;
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.concept-card p,
.concept-card li {
  font-size: 0.97rem;
  color: var(--text);
}

.concept-card ul {
  padding-left: 20px;
  margin-top: 8px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.formula-box {
  background: #ffffff;
  border: 2px dashed var(--primary);
  border-radius: 12px;
  padding: 14px 18px;
  margin-top: 12px;
  font-weight: 700;
  font-size: 1.04rem;
  color: var(--primary-dark);
  text-align: center;
}

.visual-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 14px;
  margin-top: 12px;
}

.visual-item {
  background: #ffffff;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 14px 16px;
}

.visual-item strong {
  display: block;
  color: var(--primary-dark);
  margin-bottom: 4px;
}

/* Thanh minh họa phân số / tỉ lệ */
.fraction-bar-wrap {
  margin-top: 12px;
  background: #ffffff;
  padding: 14px;
  border-radius: 12px;
  border: 1px solid var(--border);
}

.fraction-bar {
  display: flex;
  height: 28px;
  border-radius: 8px;
  overflow: hidden;
  border: 1px solid var(--border);
  margin: 8px 0 6px;
}

.fraction-part {
  flex: 1;
  border-right: 1px solid rgba(255, 255, 255, 0.7);
}

.fraction-part.filled {
  background: var(--primary);
}

.fraction-part.empty {
  background: #e2e8f0;
}

/* Nút phát âm Tiếng Anh */
.vocab-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  background: #ffffff;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px 16px;
  margin-top: 8px;
}

.btn-speak {
  border: 1px solid var(--primary);
  background: var(--primary-soft);
  color: var(--primary);
  padding: 6px 12px;
  border-radius: 999px;
  font-family: inherit;
  font-size: 0.82rem;
  font-weight: 700;
  cursor: pointer;
  white-space: nowrap;
}

.btn-speak:hover {
  background: var(--primary);
  color: #ffffff;
}

.tip-callout {
  background: var(--warning-soft);
  border: 1px solid #fde68a;
  border-radius: 14px;
  padding: 16px 20px;
  color: #92400e;
  font-size: 0.95rem;
}

.tab-footer-cta {
  margin-top: 26px;
  display: flex;
  justify-content: flex-end;
}

.btn-primary {
  border: none;
  background: var(--primary);
  color: #ffffff;
  padding: 12px 22px;
  border-radius: 12px;
  font-family: inherit;
  font-size: 0.96rem;
  font-weight: 700;
  cursor: pointer;
  transition: background 0.2s, transform 0.15s;
}

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

.btn-secondary {
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  padding: 10px 18px;
  border-radius: 10px;
  font-family: inherit;
  font-size: 0.92rem;
  font-weight: 600;
  cursor: pointer;
}

/* ===== Quiz ===== */
.quiz-progress-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text-muted);
}

.quiz-bar-track {
  height: 8px;
  background: var(--surface-soft);
  border-radius: 999px;
  overflow: hidden;
  margin-bottom: 24px;
}

.quiz-bar-fill {
  height: 100%;
  background: var(--primary);
  transition: width 0.3s ease;
}

.quiz-question-card {
  background: var(--surface-soft);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 18px;
}

.quiz-question-text {
  font-size: 1.12rem;
  font-weight: 700;
  margin-bottom: 18px;
  line-height: 1.5;
}

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

.quiz-option {
  width: 100%;
  text-align: left;
  border: 2px solid var(--border);
  background: var(--surface);
  padding: 14px 18px;
  border-radius: 12px;
  font-family: inherit;
  font-size: 0.97rem;
  font-weight: 600;
  color: var(--text);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 12px;
  transition: all 0.15s ease;
}

.quiz-option:hover:not(:disabled) {
  border-color: var(--primary);
  background: var(--primary-soft);
}

.quiz-option:disabled {
  cursor: default;
}

.quiz-option.correct {
  border-color: var(--success);
  background: var(--success-soft);
  color: #14532d;
}

.quiz-option.wrong {
  border-color: var(--danger);
  background: var(--danger-soft);
  color: #7f1d1d;
}

.option-letter {
  width: 28px;
  height: 28px;
  border-radius: 8px;
  background: var(--surface-soft);
  display: grid;
  place-items: center;
  font-weight: 800;
  font-size: 0.85rem;
  flex-shrink: 0;
}

.quiz-feedback {
  margin-top: 16px;
  padding: 16px 18px;
  border-radius: 12px;
  font-size: 0.94rem;
}

.quiz-feedback.correct {
  background: var(--success-soft);
  color: #14532d;
  border: 1px solid #86efac;
}

.quiz-feedback.wrong {
  background: var(--danger-soft);
  color: #7f1d1d;
  border: 1px solid #fca5a5;
}

.quiz-actions {
  display: flex;
  justify-content: flex-end;
  margin-top: 16px;
}

.quiz-summary {
  text-align: center;
  padding: 32px 20px;
  background: var(--surface-soft);
  border-radius: var(--radius);
}

.quiz-summary-emoji {
  font-size: 3rem;
  margin-bottom: 10px;
}

.quiz-summary h3 {
  font-size: 1.4rem;
  margin-bottom: 8px;
}

.quiz-summary p {
  color: var(--text-muted);
  margin-bottom: 20px;
}

.quiz-summary-actions {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

/* ===== Parent Teaching Guide ===== */
.parent-content {
  display: grid;
  gap: 18px;
}

.parent-card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 22px;
  background: #ffffff;
}

.parent-card h3 {
  font-size: 1.05rem;
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--primary-dark);
}

.parent-card ul,
.parent-card ol {
  padding-left: 20px;
  display: grid;
  gap: 8px;
}

.parent-card.highlight {
  background: var(--primary-soft);
  border-color: transparent;
}

/* ===== Footer ===== */
.footer {
  background: var(--surface);
  border-top: 1px solid var(--border);
  padding: 22px 0;
  text-align: center;
  font-size: 0.88rem;
  color: var(--text-muted);
}

.footer-note {
  margin-top: 4px;
  font-size: 0.8rem;
}

code {
  background: var(--surface-soft);
  padding: 2px 6px;
  border-radius: 6px;
  font-size: 0.85em;
}

/* ===== Topbar Actions & Report Button ===== */
.topbar-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.btn-report {
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  padding: 9px 14px;
  border-radius: 12px;
  font-family: inherit;
  font-size: 0.88rem;
  font-weight: 700;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: all 0.18s ease;
}

.btn-report:hover {
  border-color: var(--primary);
  color: var(--primary);
  background: var(--primary-soft);
}

/* ===== Visual SVG Diagrams & Worked Examples ===== */
.diagram-box {
  margin-top: 14px;
  background: #ffffff;
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 16px;
  text-align: center;
}

.diagram-box svg {
  max-width: 100%;
  height: auto;
  display: inline-block;
}

.diagram-caption {
  margin-top: 8px;
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
}

.worked-example {
  margin-top: 14px;
  background: #ffffff;
  border: 1px solid var(--border);
  border-left: 4px solid var(--chem);
  border-radius: 12px;
  padding: 16px 18px;
}

.worked-example-title {
  font-weight: 800;
  color: var(--chem);
  font-size: 0.96rem;
  margin-bottom: 8px;
}

.example-steps {
  display: grid;
  gap: 6px;
  margin-top: 8px;
  padding-left: 18px;
}

.example-steps li {
  font-size: 0.94rem;
}

/* ===== Quiz Timer ===== */
.quiz-timer-pill {
  background: var(--primary-soft);
  color: var(--primary-dark);
  padding: 4px 12px;
  border-radius: 999px;
  font-size: 0.84rem;
  font-weight: 700;
}

/* ===== Parent Report View ===== */
.report-filter-group {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.report-header-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px 26px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 20px;
  box-shadow: var(--shadow);
}

.report-header-card h2 {
  font-size: 1.35rem;
  font-weight: 800;
  margin-bottom: 4px;
}

.report-header-card p {
  color: var(--text-muted);
  font-size: 0.92rem;
}

.report-stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 14px;
  margin-bottom: 22px;
}

.report-stat-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
  box-shadow: var(--shadow);
}

.report-stat-label {
  font-size: 0.84rem;
  color: var(--text-muted);
  font-weight: 600;
}

.report-stat-value {
  font-size: 1.65rem;
  font-weight: 800;
  color: var(--primary);
  margin-top: 4px;
}

.report-section-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px 24px;
  margin-bottom: 20px;
  box-shadow: var(--shadow);
}

.report-section-card h3 {
  font-size: 1.08rem;
  font-weight: 800;
  margin-bottom: 14px;
}

.report-table-wrap {
  overflow-x: auto;
}

.report-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.report-table th,
.report-table td {
  text-align: left;
  padding: 11px 12px;
  border-bottom: 1px solid var(--border);
}

.report-table th {
  font-weight: 700;
  color: var(--text-muted);
  background: var(--surface-soft);
}

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

.history-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  padding: 12px 16px;
  border-radius: 12px;
  background: var(--surface-soft);
  font-size: 0.9rem;
}

.history-item-meta {
  color: var(--text-muted);
  font-size: 0.82rem;
  margin-top: 2px;
}

.history-score-badge {
  padding: 4px 12px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 0.84rem;
  background: var(--success-soft);
  color: var(--success);
}

.history-score-badge.low {
  background: var(--warning-soft);
  color: var(--warning);
}

@media (max-width: 768px) {
  .hero-card {
    grid-template-columns: 1fr;
    padding: 22px;
  }

  .topbar-inner {
    flex-direction: column;
    align-items: stretch;
  }

  .topbar-actions {
    justify-content: space-between;
  }

  .grade-switcher {
    justify-content: center;
    flex: 1;
  }

  .lesson-header,
  .lesson-tabs,
  .tab-panel {
    padding-left: 18px;
    padding-right: 18px;
  }
}