/* ============================================================
   Khoa Học Chất — Design System
   Prefix: .khc-wrap
   Chủ đề: Khoa học tự nhiên lớp 4-5 (Chất / Matter)
   ============================================================ */

.khc-wrap {
  /* --- Palette khoa học --- */
  --khc-primary:        #0e7490;   /* cyan đậm — khoa học */
  --khc-primary-light:  #0891b2;
  --khc-primary-dark:   #155e75;
  --khc-accent:         #7c3aed;   /* tím — thí nghiệm */
  --khc-gold:           #b45309;
  --khc-gold-light:     #f59e0b;
  --khc-text:           #1c1917;
  --khc-text-secondary: #374151;
  --khc-muted:          #6b7280;
  --khc-border:         #bae6f0;
  --khc-border-accent:  #67e8f9;
  --khc-bg-warm:        #ecfeff;
  --khc-bg-surface:     #f8fafb;
  --khc-shadow-sm:      0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --khc-shadow:         0 4px 16px rgba(0,0,0,0.07), 0 1px 4px rgba(0,0,0,0.04);
  --khc-shadow-lg:      0 12px 40px rgba(0,0,0,0.09), 0 4px 12px rgba(0,0,0,0.05);
  --khc-radius:         16px;
  --khc-radius-lg:      24px;

  /* Màu 8 chủ đề */
  --khc-t1: #0284c7;   /* xanh dương — ba thể */
  --khc-t2: #0891b2;   /* cyan — nước */
  --khc-t3: #0d9488;   /* teal — không khí */
  --khc-t4: #65a30d;   /* xanh lá — đất */
  --khc-t5: #d97706;   /* cam — hỗn hợp */
  --khc-t6: #dc2626;   /* đỏ — biến đổi */
  --khc-t7: #7c3aed;   /* tím — vật liệu */
  --khc-t8: #eab308;   /* vàng — ánh sáng */
  --khc-t9: #6366f1;   /* indigo — hệ cơ quan */
  --khc-t10: #ea580c;  /* cam đậm — sức khỏe */

  font-size: 1rem;
  line-height: 1.7;
  color: var(--khc-text);
}

/* ---- Transitions ---- */
.khc-wrap .khc-event-card,
.khc-wrap .accordion-item {
  transition: transform 0.22s ease, box-shadow 0.22s ease, border-color 0.22s ease;
}

/* ============================================================
   Hero
   ============================================================ */
.khc-wrap .khc-hero-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 32px;
  margin-bottom: 48px;
}
@media (max-width: 900px) {
  .khc-wrap .khc-hero-grid { grid-template-columns: 1fr; }
}

.khc-wrap .khc-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  border-radius: 999px;
  background: var(--khc-bg-warm);
  color: var(--khc-primary);
  font-size: 0.92rem;
  font-weight: 700;
  border: 1px solid var(--khc-border-accent);
  margin-bottom: 18px;
  letter-spacing: 0.01em;
}

.khc-wrap .khc-hero-title {
  font-size: clamp(1.7rem, 3vw, 2.5rem);
  line-height: 1.15;
  letter-spacing: -0.025em;
  margin: 0 0 16px;
  font-weight: 800;
  color: var(--khc-primary);
}

.khc-wrap .khc-hero-desc {
  color: var(--khc-text-secondary);
  font-size: 1.05rem;
  margin: 0 0 20px;
  line-height: 1.75;
}

.khc-wrap .khc-hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 24px;
}

/* ---- Buttons ---- */
.khc-wrap .khc-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border-radius: 12px;
  padding: 11px 22px;
  font-weight: 700;
  font-size: 0.97rem;
  transition: all 0.22s ease;
  cursor: pointer;
  border: 1px solid transparent;
  text-decoration: none;
}
.khc-wrap .khc-btn-primary {
  background: var(--khc-primary);
  color: #fff;
  box-shadow: 0 4px 14px rgba(14, 116, 144, 0.3);
}
.khc-wrap .khc-btn-primary:hover {
  background: var(--khc-primary-light);
  color: #fff;
  transform: translateY(-1px);
}
.khc-wrap .khc-btn-secondary {
  border-color: var(--khc-border);
  background: #fff;
  color: var(--khc-text);
  box-shadow: var(--khc-shadow-sm);
}
.khc-wrap .khc-btn-secondary:hover {
  border-color: var(--khc-primary);
  color: var(--khc-primary);
}
.khc-wrap .khc-btn-light {
  background: #fff;
  color: var(--khc-primary);
  border: 1px solid rgba(255,255,255,0.6);
  font-weight: 700;
}
.khc-wrap .khc-btn-ghost {
  color: #fff;
  border: 1px solid rgba(255,255,255,0.35);
  background: rgba(255,255,255,0.12);
}
.khc-wrap .khc-btn-ghost:hover {
  background: rgba(255,255,255,0.22);
  color: #fff;
  transform: translateY(-1px);
}

/* ============================================================
   Hero Panel
   ============================================================ */
.khc-wrap .khc-hero-panel {
  background: #fff;
  border: 1px solid var(--khc-border);
  border-radius: var(--khc-radius-lg);
  padding: 26px;
  box-shadow: var(--khc-shadow);
  position: relative;
  overflow: hidden;
}
.khc-wrap .khc-hero-panel::before {
  content: "";
  position: absolute;
  width: 260px;
  height: 260px;
  top: -100px;
  right: -80px;
  border-radius: 999px;
  background: radial-gradient(circle, rgba(14,116,144,0.07) 0%, transparent 70%);
  pointer-events: none;
}
.khc-wrap .khc-panel-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--khc-border);
}
.khc-wrap .khc-panel-title {
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--khc-primary);
}
.khc-wrap .khc-status {
  padding: 5px 13px;
  border-radius: 10px;
  font-size: 0.84rem;
  font-weight: 700;
  background: var(--khc-bg-warm);
  color: var(--khc-primary);
  border: 1px solid var(--khc-border-accent);
  white-space: nowrap;
}
.khc-wrap .khc-topic-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.khc-wrap .khc-topic-row {
  display: grid;
  grid-template-columns: 62px 1fr;
  gap: 12px;
  align-items: start;
  padding: 10px 14px;
  border-radius: 10px;
  background: var(--khc-bg-surface);
  border: 1px solid var(--khc-border);
}
.khc-wrap .khc-topic-row:hover {
  border-color: var(--khc-border-accent);
  background: var(--khc-bg-warm);
}
.khc-wrap .khc-topic-label {
  font-weight: 800;
  font-size: 0.85rem;
  line-height: 1.4;
  text-align: center;
}
.khc-wrap .khc-topic-row h4 {
  margin: 0 0 3px;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--khc-text);
  line-height: 1.35;
}
.khc-wrap .khc-topic-row small {
  color: var(--khc-muted);
  font-size: 0.8rem;
}

/* ============================================================
   Stats row
   ============================================================ */
.khc-wrap .khc-stats-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
  margin-bottom: 28px;
}
@media (max-width: 600px) {
  .khc-wrap .khc-stats-row { grid-template-columns: repeat(2, 1fr); }
}
.khc-wrap .khc-stat-card {
  background: #fff;
  border: 1px solid var(--khc-border);
  border-radius: var(--khc-radius);
  padding: 20px 16px;
  text-align: center;
  box-shadow: var(--khc-shadow-sm);
}
.khc-wrap .khc-stat-number {
  font-size: 2rem;
  font-weight: 800;
  color: var(--khc-primary);
  line-height: 1;
  margin-bottom: 6px;
}
.khc-wrap .khc-stat-label {
  font-size: 0.83rem;
  color: var(--khc-muted);
  font-weight: 600;
  line-height: 1.4;
}

/* ============================================================
   Memory tip box
   ============================================================ */
.khc-wrap .khc-memory-box {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  background: linear-gradient(135deg, #fef9c3 0%, #fef3c7 100%);
  border: 1px solid #fcd34d;
  border-left: 4px solid #d97706;
  border-radius: 12px;
  padding: 18px 22px;
  margin: 24px 0 32px;
}
.khc-wrap .khc-memory-icon {
  font-size: 1.7rem;
  line-height: 1;
  flex-shrink: 0;
  margin-top: 2px;
}
.khc-wrap .khc-memory-label {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: #92400e;
  margin-bottom: 5px;
}
.khc-wrap .khc-memory-seq {
  font-size: 1.02rem;
  font-weight: 800;
  color: #78350f;
  margin-bottom: 2px;
}
.khc-wrap .khc-memory-sub {
  font-size: 0.88rem;
  color: #92400e;
  margin-bottom: 6px;
  font-weight: 600;
}
.khc-wrap .khc-memory-heroes {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 16px;
  font-size: 0.82rem;
  color: #a16207;
}
.khc-wrap .khc-memory-heroes span::before {
  content: "•";
  margin-right: 6px;
  color: #d97706;
}

/* ============================================================
   Section
   ============================================================ */
.khc-wrap .khc-section {
  margin-bottom: 44px;
}
.khc-wrap .khc-section-header {
  margin-bottom: 24px;
}
.khc-wrap .khc-section-header h2 {
  font-size: clamp(1.3rem, 2.4vw, 1.85rem);
  font-weight: 800;
  color: var(--khc-primary);
  line-height: 1.25;
  margin: 0 0 10px;
}
.khc-wrap .khc-section-header p {
  font-size: 1rem;
  color: var(--khc-text-secondary);
  line-height: 1.7;
  margin: 0;
}

/* ============================================================
   Topic block
   ============================================================ */
.khc-wrap .khc-topic-block {
  background: #fff;
  border: 1px solid var(--khc-border);
  border-radius: var(--khc-radius-lg);
  margin-bottom: 24px;
  overflow: hidden;
  box-shadow: var(--khc-shadow-sm);
}
.khc-wrap .khc-topic-block-title {
  font-size: 1.05rem;
  font-weight: 800;
  padding: 18px 24px;
  border-bottom: 1px solid var(--khc-border);
  color: #fff;
}
.khc-wrap .khc-topic-block-title.t1 { background: var(--khc-t1); }
.khc-wrap .khc-topic-block-title.t2 { background: var(--khc-t2); }
.khc-wrap .khc-topic-block-title.t3 { background: var(--khc-t3); }
.khc-wrap .khc-topic-block-title.t4 { background: var(--khc-t4); }
.khc-wrap .khc-topic-block-title.t5 { background: var(--khc-t5); }
.khc-wrap .khc-topic-block-title.t6 { background: var(--khc-t6); }
.khc-wrap .khc-topic-block-title.t7 { background: var(--khc-t7); }
.khc-wrap .khc-topic-block-title.t8  { background: var(--khc-t8); }
.khc-wrap .khc-topic-block-title.t9  { background: var(--khc-t9); }
.khc-wrap .khc-topic-block-title.t10 { background: var(--khc-t10); }

/* ============================================================
   Event grid / cards
   ============================================================ */
.khc-wrap .khc-event-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
  gap: 18px;
  padding: 20px 22px;
}
.khc-wrap .khc-event-grid.khc-event-grid-2 {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}
.khc-wrap .khc-event-grid.khc-event-grid-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}
.khc-wrap .khc-event-grid.khc-event-grid-4 {
  grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
}
@media (max-width: 1100px) {
  .khc-wrap .khc-event-grid.khc-event-grid-3 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}
@media (max-width: 780px) {
  .khc-wrap .khc-event-grid.khc-event-grid-2 { grid-template-columns: 1fr; }
}
@media (max-width: 700px) {
  .khc-wrap .khc-event-grid             { grid-template-columns: 1fr; padding: 14px; }
  .khc-wrap .khc-event-grid.khc-event-grid-2 { grid-template-columns: 1fr; }
  .khc-wrap .khc-event-grid.khc-event-grid-3 { grid-template-columns: 1fr; }
  .khc-wrap .khc-event-grid.khc-event-grid-4 { grid-template-columns: 1fr; }

  /* Panel head wraps on small screens */
  .khc-wrap .khc-panel-head { flex-wrap: wrap; gap: 8px; }

  /* Card top allows tag to wrap below title */
  .khc-wrap .khc-event-card-top { flex-wrap: wrap; }

  /* Reduce inner padding */
  .khc-wrap .khc-event-card             { padding: 16px; }
  .khc-wrap .khc-topic-block-title      { padding: 14px 16px; }
  .khc-wrap .khc-table-wrap             { padding: 0 14px 14px; }
  .khc-wrap > .khc-table-wrap           { padding: 14px; }
  .khc-wrap .khc-hero-panel             { padding: 18px 16px; }
  .khc-wrap .khc-section                { margin-bottom: 28px; }
  .khc-wrap .khc-topic-block            { margin-bottom: 16px; }

  /* Memory tip box stacks */
  .khc-wrap .khc-memory-box             { flex-direction: column; padding: 16px 18px; }
}

/* ---- Extra small (≤ 480px) ---- */
@media (max-width: 480px) {
  .khc-wrap .khc-hero-title             { font-size: 1.55rem; }
  .khc-wrap .khc-section-header h2      { font-size: 1.2rem; }
  .khc-wrap .khc-topic-block-title      { font-size: 0.95rem; }
  .khc-wrap .khc-table-section-title    { font-size: 0.95rem; padding: 12px 16px; }
  .khc-wrap .khc-event-card             { padding: 14px 12px; }
  .khc-wrap .khc-event-card-top h4      { font-size: 0.97rem; }
  .khc-wrap .khc-event-card p,
  .khc-wrap .khc-event-card ul,
  .khc-wrap .khc-event-card ol          { font-size: 0.9rem; }
  .khc-wrap .khc-table                  { font-size: 0.82rem; }
  .khc-wrap .khc-table th,
  .khc-wrap .khc-table td               { padding: 8px 10px; }
  .khc-wrap .khc-hero-panel             { padding: 14px 12px; }
  .khc-wrap .khc-highlight-note         { padding: 10px 14px; }
  .khc-wrap .khc-btn                    { padding: 10px 16px; font-size: 0.9rem; }
  .khc-wrap .khc-cta-box                { padding: 22px 16px; }
  /* Stats row: 1 card per row on very small screens */
  .khc-wrap .khc-stats-row              { grid-template-columns: 1fr; }
}
.khc-wrap .khc-event-card {
  background: #fff;
  border: 1px solid var(--khc-border);
  border-radius: var(--khc-radius);
  padding: 20px 22px;
  box-shadow: var(--khc-shadow-sm);
  position: relative;
}
.khc-wrap .khc-event-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--khc-shadow);
}

/* Border top color per topic */
.khc-wrap .khc-event-card.t1 { border-top: 3px solid var(--khc-t1); }
.khc-wrap .khc-event-card.t2 { border-top: 3px solid var(--khc-t2); }
.khc-wrap .khc-event-card.t3 { border-top: 3px solid var(--khc-t3); }
.khc-wrap .khc-event-card.t4 { border-top: 3px solid var(--khc-t4); }
.khc-wrap .khc-event-card.t5 { border-top: 3px solid var(--khc-t5); }
.khc-wrap .khc-event-card.t6 { border-top: 3px solid var(--khc-t6); }
.khc-wrap .khc-event-card.t7 { border-top: 3px solid var(--khc-t7); }
.khc-wrap .khc-event-card.t8 { border-top: 3px solid var(--khc-t8); }

.khc-wrap .khc-event-card-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 10px;
}
.khc-wrap .khc-event-card-top h4 {
  margin: 0;
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--khc-text);
  line-height: 1.3;
}
.khc-wrap .khc-event-tag {
  padding: 3px 10px;
  border-radius: 8px;
  font-size: 0.75rem;
  font-weight: 700;
  background: var(--khc-bg-warm);
  color: var(--khc-primary);
  border: 1px solid var(--khc-border-accent);
  white-space: nowrap;
  flex-shrink: 0;
}
.khc-wrap .khc-event-card p {
  font-size: 0.95rem;
  color: var(--khc-text-secondary);
  line-height: 1.7;
  margin: 0 0 10px;
}
.khc-wrap .khc-event-card p:last-child { margin-bottom: 0; }
.khc-wrap .khc-event-card ul,
.khc-wrap .khc-event-card ol {
  margin: 0 0 12px;
  padding-left: 22px;
  font-size: 0.95rem;
  color: var(--khc-text-secondary);
  line-height: 1.7;
}
.khc-wrap .khc-event-card li { margin-bottom: 4px; }

/* ---- Tags ---- */
.khc-wrap .khc-tag {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 8px;
  font-size: 0.74rem;
  font-weight: 700;
  margin-bottom: 10px;
}
.khc-wrap .khc-tag-khai-niem {
  background: #eff6ff;
  color: #1d4ed8;
  border: 1px solid #bfdbfe;
}
.khc-wrap .khc-tag-thuc-hanh {
  background: #ecfdf5;
  color: #059669;
  border: 1px solid #a7f3d0;
}
.khc-wrap .khc-tag-chuyen-the {
  background: #ecfeff;
  color: #0891b2;
  border: 1px solid #a5f3fc;
}
.khc-wrap .khc-tag-tu-nhien {
  background: #f0fdf4;
  color: #15803d;
  border: 1px solid #bbf7d0;
}
.khc-wrap .khc-tag-lich-su {
  background: #fef3c7;
  color: #b45309;
  border: 1px solid #fcd34d;
}
.khc-wrap .khc-tag-vat-lieu {
  background: #f5f3ff;
  color: #7c3aed;
  border: 1px solid #c4b5fd;
}
.khc-wrap .khc-tag-ung-dung {
  background: #fef2f2;
  color: #dc2626;
  border: 1px solid #fecaca;
}

/* ============================================================
   Highlight note (trong card)
   ============================================================ */
.khc-wrap .khc-highlight-note {
  background: linear-gradient(135deg, #ecfeff 0%, #f0f9ff 100%);
  border: 1px solid var(--khc-border-accent);
  border-left: 4px solid var(--khc-primary);
  border-radius: 10px;
  padding: 14px 18px;
  margin-top: 12px;
}
.khc-wrap .khc-highlight-note:last-child { margin-bottom: 0; }
.khc-wrap .khc-highlight-label {
  font-size: 0.74rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--khc-primary-dark);
  margin-bottom: 4px;
}
.khc-wrap .khc-highlight-note p {
  font-size: 0.9rem;
  color: var(--khc-primary-dark);
  line-height: 1.65;
  margin: 0;
  font-weight: 500;
}

/* ============================================================
   Table
   ============================================================ */
.khc-wrap .khc-table-wrap {
  overflow-x: auto;
  padding: 0 22px 22px;
}
.khc-wrap .khc-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
  line-height: 1.6;
}
.khc-wrap .khc-table th,
.khc-wrap .khc-table td {
  padding: 12px 16px;
  border: 1px solid var(--khc-border);
  vertical-align: top;
}
.khc-wrap .khc-table thead th {
  background: var(--khc-primary);
  color: #fff;
  font-weight: 700;
  text-align: left;
}
.khc-wrap .khc-table tbody tr:nth-child(even) {
  background: var(--khc-bg-surface);
}
.khc-wrap .khc-table tbody tr:hover {
  background: var(--khc-bg-warm);
}

/* stand-alone table (outside topic-block) */
.khc-wrap > .khc-table-wrap {
  background: #fff;
  border: 1px solid var(--khc-border);
  border-radius: var(--khc-radius);
  margin-bottom: 24px;
  box-shadow: var(--khc-shadow-sm);
  padding: 18px;
}

/* table section — lightweight container for standalone tables */
.khc-wrap .khc-table-section {
  background: #fff;
  border: 1px solid var(--khc-border);
  border-top: 3px solid var(--khc-primary);
  border-radius: var(--khc-radius-lg);
  margin-bottom: 24px;
  overflow: hidden;
  box-shadow: var(--khc-shadow-sm);
}
.khc-wrap .khc-table-section-title {
  font-size: 1.02rem;
  font-weight: 800;
  padding: 15px 22px;
  color: var(--khc-primary-dark);
  background: linear-gradient(135deg, var(--khc-bg-warm) 0%, #e0f2fe 100%);
  border-bottom: 1px solid var(--khc-border);
  letter-spacing: 0.015em;
}
.khc-wrap .khc-table-section .khc-table-wrap {
  padding: 20px 22px 22px;
}

/* flashcard group sub-heading — lightweight divider inside flashcard block */
.khc-wrap .khc-flashcard-group {
  font-size: 0.9rem;
  font-weight: 700;
  padding: 8px 20px;
  margin-top: 16px;
  color: var(--khc-primary-dark);
  background: linear-gradient(90deg, var(--khc-bg-warm) 0%, #f0f9ff 100%);
  border-left: 3px solid var(--khc-primary-light);
  border-radius: 0 6px 6px 0;
  letter-spacing: 0.01em;
}

/* ============================================================
   FAQ Accordion
   ============================================================ */
.khc-wrap .accordion {
  border-radius: var(--khc-radius);
  overflow: hidden;
}
.khc-wrap .accordion-item {
  border: 1px solid var(--khc-border) !important;
  margin-bottom: 8px;
  border-radius: 12px !important;
  overflow: hidden;
}
.khc-wrap .accordion-item:last-child { margin-bottom: 0; }
.khc-wrap .accordion-button {
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--khc-text);
  padding: 16px 20px;
  background: #fff;
  line-height: 1.5;
}
.khc-wrap .accordion-button:not(.collapsed) {
  background: var(--khc-bg-warm);
  color: var(--khc-primary);
  box-shadow: none;
}
.khc-wrap .accordion-button:focus {
  box-shadow: 0 0 0 3px rgba(14, 116, 144, 0.15);
}
.khc-wrap .accordion-body {
  font-size: 0.93rem;
  color: var(--khc-text-secondary);
  line-height: 1.75;
  padding: 16px 20px;
}

/* ============================================================
   CTA Box
   ============================================================ */
.khc-wrap .khc-cta-box {
  display: grid;
  grid-template-columns: 1fr 2fr auto;
  align-items: center;
  gap: 28px;
  background: linear-gradient(135deg, var(--khc-primary-dark) 0%, var(--khc-primary) 100%);
  border-radius: var(--khc-radius-lg);
  padding: 36px 40px;
  margin-top: 32px;
}
@media (max-width: 860px) {
  .khc-wrap .khc-cta-box { grid-template-columns: 1fr; text-align: center; padding: 28px 20px; }
  .khc-wrap .khc-cta-actions { align-items: center; }
}
.khc-wrap .khc-cta-title h3 {
  font-size: 1.25rem;
  font-weight: 800;
  margin: 0;
  line-height: 1.35;
  color: #fff;
}
.khc-wrap .khc-cta-desc p {
  color: rgba(255,255,255,0.88);
  font-size: 0.95rem;
  line-height: 1.7;
  margin: 0;
}
.khc-wrap .khc-cta-actions {
  display: flex;
  flex-direction: column;
  gap: 10px;
  flex-shrink: 0;
}