body {
  font-family: 'HarmonyOS_Regular';
  background-color: #f4f7f6;
  color: #333;
  margin: 0;
  padding: 20px;
}

header {
  text-align: center;
  margin-bottom: 40px;
}

h1 {
  color: #2c3e50;
}

#fileInput {
  padding: 10px 15px;
  border: 2px dashed #3498db;
  border-radius: 5px;
  cursor: pointer;
  transition: background-color 0.3s, border-color 0.3s;
}

#fileInput:hover {
  background-color: #ecf0f1;
  border-color: #2980b9;
}

.student-card {
  background-color: #fff;
  border-radius: 8px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
  margin-bottom: 30px;
  padding: 20px;
  overflow: hidden;
}

.student-card h2 {
  color: #3498db;
  border-bottom: 2px solid #ecf0f1;
  padding-bottom: 10px;
}

.charts-container {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  align-items: flex-start;
}

.chart-wrapper {
  flex: 1;
  min-width: 300px;
}

.tree-wrapper {
  flex: 2;
  min-width: 400px;
}

.chart-wrapper h3,
.tree-wrapper h3 {
  text-align: center;
  color: #7f8c8d;
}

.node circle {
  stroke: #333;
  stroke-width: 1.5px;
}

.node text {
  font: 12px sans-serif;
}

.link {
  fill: none;
  stroke: #ccc;
  stroke-width: 1.5px;
}

.node.learned circle {
  fill: #52c41a;
}

.node.progressing circle {
  fill: #f39c12;
}

.node.not-started circle {
  fill: #bfbfbf;
}

.tooltip {
  position: absolute;
  text-align: center;
  width: auto;
  height: auto;
  padding: 8px;
  font: 12px sans-serif;
  background: #2c3e50;
  color: #fff;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.2s;
}

center {
  text-align: center;
}
/* 学生卡片底部文字区域样式 */
.card-footer {
  text-align: center;
  margin-top: 24px;
  font-size: 1.1em;
  font-weight: 500;
  padding: 12px 0 0 0;
  background: linear-gradient(90deg, #6dd5ed 0%, #2193b0 100%);
  color: #fff;
  border-radius: 0 0 8px 8px;
  letter-spacing: 1px;
}