為什麼邊框樣式不適用於黏性定位的表標題，如何修復它？

#wrapper {
  width: 100%;
  height: 150px;
  overflow: auto;
}

table {
  width: 100%;
  text-align: center;
  border-collapse: separate; /* Don't collapse */
  border-spacing: 0;
}

table th {
  /* Apply both top and bottom borders to the <th> */
  border-top: 2px solid;
  border-bottom: 2px solid;
  border-right: 2px solid;
}

table td {
  /* For cells, apply the border to one of each side only (right but not left, bottom but not top) */
  border-bottom: 2px solid;
  border-right: 2px solid;
}

table th:first-child,
table td:first-child {
  /* Apply a left border on the first <td> or <th> in a row */
  border-left: 2px solid;
}

table thead th {
  position: sticky;
  top: 0;
  background-color: #edecec;
}