chrome/browser/resources/file_manager/css/tile_view.css

/* Copyright (c) 2012 The Chromium Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file. */

.tile-view {
  -webkit-box-align: center;
  -webkit-box-orient: horizontal;
  -webkit-box-pack: start;
  display: -webkit-box;
  overflow-x: scroll;
  overflow-y: hidden;
  position: relative;
}

.tile-box {
  background: gray;
  border: solid 1px red;
  display: block;
  position: absolute;
  transition: all ease 300ms;
}

.tile-box > img {
  height: 100%;
  width: 100%;
}