seahub/frontend/src/css/groups.css

.cur-view-content-groups thead th { /* overwrite bootstrap styles */
  padding: 0;
  font-size: 0;
  border: 0;
}

.cur-view-content-groups td { /* overwrite bootstrap styles */
  border-top:0;
}

.group-item-heading {
  font-size: 16px;
  font-weight: normal;
  padding: 3px; 
  border-bottom: 1px solid #e6e6e6;
  margin: 12px 0 0; 
}
.group-item-empty-tip {
  color: #a4a4a4;
  text-align: center;
  padding: 4px 0;
  border-bottom: 1px solid #e5e5e5;
  margin: 0 0 32px;
}

.group-top-op-icon {
    display: inline-block;
    font-size: 22px;
    margin: 3px 0 0 10px;
}

.department-group-icon {
  margin-left: 0.25rem;
  color:#888;
}