//.js
res.data.content= res.data.content.replace(/<tr/g, '<tr class="tr"'),    
res.data.content = res.data.content.replace(/<td/g, '<td class="td"'),

//.wxss
.quill-better-table {
  border-collapse: collapse;
  border: 1px solid #414040;
}
.quill-better-table .tr .td {
  border: 1px solid #414040;
}