superset-frontend/packages/superset-frontend/src/dashboard/stylesheets/components/row.less

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
.grid-row {
  position: relative;
  display: flex;
  flex-direction: row;
  flex-wrap: nowrap;
  align-items: flex-start;
  width: 100%;
  height: fit-content;
}

/* gutters between elements in a row */
.grid-row > :not(:only-child):not(:last-child):not(.hover-menu) {
  margin-right: 16px;
}

/* hover indicator */
.dashboard--editing {
  .grid-row:after,
  .dashboard-component-tabs > .hover-menu:hover + div:after {
    border: 1px dashed transparent;
    content: '';
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    z-index: @z-index-chart;
    pointer-events: none;
  }

  .resizable-container.resizable-container--resizing:hover > .grid-row:after,
  .hover-menu:hover + .grid-row:after,
  .dashboard-component-tabs > .hover-menu:hover + div:after {
    border: 1px dashed @indicator-color;
    z-index: @z-index-chart--dragging;
  }

  .grid-row:after,
  .dashboard-component-tabs > .hover-menu + div:after {
    border: 1px dashed @gray-light;
  }

  /* provide hit area in case row contents is edge to edge */
  .dashboard-component-tabs-content {
    .dragdroppable-row {
      padding-top: 16px;
    }
  }
}

.grid-row.grid-row--empty {
  /* this centers the empty note content */
  align-items: center;
  height: 100px;

  &:before {
    position: absolute;
    top: 0;
    left: 0;
    content: 'Empty row';
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
    color: @gray;
  }
}