/**
 * Framework 90: 小课堂 · 黑板粉笔描画 (Classroom Chalkboard & Chalk Strokes)
 * 配套 054 薄荷治愈 - 白色明朗纯净版
 */

/* 1. 黑板主画板容器 (Classroom Main Blackboard Feature) */
.chalkboard-frame {
  background: var(--bg-chalkboard);
  border: 8px solid #2d4a3e;
  border-radius: 20px;
  box-shadow:
    inset 0 0 40px rgba(0, 0, 0, 0.6),
    0 16px 40px rgba(0, 0, 0, 0.15),
    0 0 0 2px rgba(16, 185, 129, 0.4);
  padding: 32px;
  position: relative;
  overflow: hidden;
  background-image: 
    radial-gradient(circle at 50% 50%, rgba(20, 60, 48, 0.4) 0%, rgba(10, 28, 22, 0.8) 100%),
    repeating-linear-gradient(45deg, rgba(255, 255, 255, 0.015) 0px, rgba(255, 255, 255, 0.015) 2px, transparent 2px, transparent 8px);
}

/* 黑板下方的粉笔槽 (Chalk Tray) */
.chalk-tray {
  position: absolute;
  bottom: 0;
  left: 30px;
  right: 30px;
  height: 10px;
  background: #1c332b;
  border-top: 2px solid #3d6354;
  border-radius: 4px 4px 0 0;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 12px;
  padding: 0 16px;
}

.chalk-stick {
  width: 24px;
  height: 6px;
  border-radius: 3px;
  display: inline-block;
  opacity: 0.9;
}

.chalk-mint { background: var(--chalk-mint); box-shadow: 0 0 6px var(--chalk-mint); }
.chalk-cream { background: var(--chalk-cream); box-shadow: 0 0 6px var(--chalk-cream); }
.chalk-white { background: var(--chalk-white); box-shadow: 0 0 6px rgba(255, 255, 255, 0.7); }
.chalk-eraser {
  width: 32px;
  height: 7px;
  background: #5c4033;
  border-radius: 2px;
  border-top: 2px solid #8d6e63;
}

/* 粉笔质感文字阴影 */
.chalk-text {
  color: #ffffff;
  text-shadow: 
    0 0 2px rgba(255, 255, 255, 0.85),
    0 0 8px rgba(110, 231, 183, 0.45);
}

.chalk-text-mint {
  color: var(--chalk-mint);
  text-shadow: 
    0 0 2px rgba(110, 231, 183, 0.9),
    0 0 10px rgba(52, 211, 153, 0.5);
}

.chalk-text-cream {
  color: var(--chalk-cream);
  text-shadow: 
    0 0 2px rgba(254, 240, 138, 0.9),
    0 0 8px rgba(254, 240, 138, 0.4);
}

/* 白底小课堂卡片 (Chalk Box) */
.chalk-box {
  border: 1.8px dashed rgba(16, 185, 129, 0.45);
  border-radius: 14px;
  padding: 24px;
  background: #f0fdf4;
  backdrop-filter: blur(8px);
  position: relative;
  transition: all 0.3s ease;
}

.chalk-box:hover {
  border-color: var(--color-mint-brand);
  background: #e6fffa;
  box-shadow: 0 8px 24px rgba(16, 185, 129, 0.12);
}

/* 黑板小课堂特色 Hero 交互画板 */
.classroom-hero-board {
  position: relative;
  padding: 28px;
  background: #0e2920;
  border: 3px solid #10b981;
  border-style: solid;
  border-radius: 18px;
  box-shadow: inset 0 0 30px rgba(0, 0, 0, 0.5), 0 12px 32px rgba(0, 0, 0, 0.2);
}

.board-top-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1.5px dashed rgba(52, 211, 153, 0.35);
  padding-bottom: 14px;
  margin-bottom: 20px;
}

.board-lesson-pill {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--chalk-cream);
  background: rgba(254, 240, 138, 0.12);
  border: 1px dashed var(--chalk-cream);
  padding: 4px 12px;
  border-radius: 6px;
}

.board-live-pulse {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.8rem;
  color: var(--chalk-mint);
  font-family: var(--font-mono);
}

.board-live-dot {
  width: 8px;
  height: 8px;
  background: var(--chalk-mint);
  border-radius: 50%;
  animation: pulseMint 1.8s infinite;
}

/* 手绘网络拓扑图 (SVG Chalk Blackboard Drawing) */
.chalk-topology-container {
  width: 100%;
  height: 240px;
  position: relative;
  margin: 16px 0;
}

.chalk-svg-canvas {
  width: 100%;
  height: 100%;
}

/* 黑板遥测指标卡 (Live Blackboard Metrics) */
.board-metrics-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-top: 18px;
  padding-top: 16px;
  border-top: 1.5px dashed rgba(52, 211, 153, 0.25);
}

.board-metric-card {
  background: rgba(7, 23, 18, 0.65);
  border: 1px dashed rgba(110, 231, 183, 0.35);
  border-radius: 10px;
  padding: 10px 12px;
  text-align: center;
}

.board-metric-label {
  font-size: 0.76rem;
  color: rgba(248, 250, 252, 0.65);
  margin-bottom: 4px;
}

.board-metric-val {
  font-family: var(--font-mono);
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--chalk-mint);
}

/* 2. 小课堂公开课 4 大讲义系统 (4 Classroom Masterclass Lectures - White Theme) */
.lectures-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 28px;
}

.lecture-card {
  background: #ffffff;
  border: 2px dashed rgba(16, 185, 129, 0.4);
  border-radius: 18px;
  padding: 32px;
  position: relative;
  transition: all 0.35s cubic-bezier(0.16, 1, 0.3, 1);
  display: flex;
  flex-direction: column;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.04);
}

.lecture-card:hover {
  transform: translateY(-4px);
  border-color: var(--color-mint-brand);
  background: #f0fdf4;
  box-shadow: 0 12px 30px rgba(16, 185, 129, 0.12);
}

.lecture-badge-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 18px;
}

.lecture-num {
  font-family: var(--font-mono);
  font-size: 0.88rem;
  font-weight: 800;
  color: #065f46;
  background: #f0fdf4;
  padding: 4px 10px;
  border-radius: 6px;
  border: 1px dashed var(--color-mint-brand);
}

.lecture-tag {
  font-size: 0.78rem;
  font-weight: 700;
  color: #065f46;
  background: #dcfce7;
  padding: 4px 10px;
  border-radius: 9999px;
}

.lecture-title {
  font-size: 1.35rem;
  font-weight: 800;
  color: #0f172a;
  line-height: 1.4;
  margin-bottom: 14px;
}

.lecture-chalk-summary {
  font-size: 0.96rem;
  color: #334155;
  line-height: 1.7;
  margin-bottom: 22px;
  flex-grow: 1;
}

/* 讲义手绘黑板黑盒 (Whiteboard Style Diagram Snippet) */
.lecture-chalk-diagram {
  background: #f0fdf4;
  border: 1px dashed rgba(16, 185, 129, 0.4);
  border-radius: 12px;
  padding: 14px 16px;
  margin-bottom: 20px;
  font-family: var(--font-mono);
  font-size: 0.84rem;
  color: #065f46;
  line-height: 1.6;
}

.diagram-line {
  display: flex;
  align-items: center;
  gap: 8px;
}

.lecture-footer-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--color-mint-dark);
}

.lecture-footer-link svg {
  width: 16px;
  height: 16px;
  transition: transform 0.25s ease;
}

.lecture-footer-link:hover svg {
  transform: translateX(4px);
}

/* 3. 全球专线黑板节点高亮交互面板 (Classroom Global Nodes HUD) */
.classroom-nodes-wrapper {
  background: #f8fafc;
  border: 2px dashed rgba(16, 185, 129, 0.35);
  border-radius: 20px;
  padding: 36px;
  margin-top: 40px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.04);
}

.nodes-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
  margin-top: 24px;
}

.node-board-card {
  background: #ffffff;
  border: 1px dashed rgba(16, 185, 129, 0.3);
  border-radius: 12px;
  padding: 16px;
  transition: all 0.25s ease;
  cursor: pointer;
  position: relative;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.03);
}

.node-board-card:hover,
.node-board-card.active {
  border-color: var(--color-mint-brand);
  background: #ecfdf5;
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(16, 185, 129, 0.12);
}

.node-flag-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 8px;
}

.node-name {
  font-size: 1rem;
  font-weight: 700;
  color: #0f172a;
}

.node-ping-badge {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 700;
  color: #065f46;
  background: #dcfce7;
  padding: 2px 8px;
  border-radius: 4px;
}

.node-specs {
  font-size: 0.78rem;
  color: #64748b;
}

/* 响应式断点 */
@media (max-width: 900px) {
  .lectures-grid {
    grid-template-columns: 1fr;
  }
  .nodes-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 520px) {
  .chalkboard-frame {
    padding: 20px 16px;
    border-width: 4px;
  }
  .board-metrics-row {
    grid-template-columns: 1fr;
    gap: 8px;
  }
  .nodes-grid {
    grid-template-columns: 1fr;
  }
}