codelab.css

/*
 * Copyright 2015 Google Inc. All rights reserved.
 *
 * Licensed 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.
 */

body {
  background: #263035;
}

.ball {
  border-radius: 1000px;
  background: #f44336;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.5);
  height: 64px;
  width: 64px;
  color: white;
  margin: 12px;
  position: relative;
  cursor: pointer;
  display: inline-block;
  box-sizing: border-box;
  border: 4px solid transparent;
  -webkit-user-select: none;
     -moz-user-select: none;
      -ms-user-select: none;
  user-select: none;
  transition: border-color 0.125s;
}

.ball i {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  text-align: center;
  line-height: 56px !important;
  font-size: 38px !important;
}

.ball::after {
  content: "";
  opacity: 0;
  background: rgba(255, 255, 255, 0.75);
  position: absolute;
  top: -4px;
  left: -4px;
  right: -4px;
  bottom: -4px;
  border-radius: 100px;
  transition: opacity 0.25s;
}
.ball:active::after {
  opacity: .75;
}

.icons {
  display: -webkit-flex;
  display: flex;
  -webkit-flex-flow: row wrap;
  flex-flow: row wrap;
  -webkit-justify-content: space-around;
  justify-content: space-around;
  -webkit-align-content: flex-start;
  align-content: flex-start;
}
.icons.main {
  max-width: 400px;
  margin: 0 auto;
  min-height: 400px;
}

.group {
  position: relative;
}
.group .popup {
  visibility: hidden;
  position: absolute;

  z-index: 1;
  overflow: hidden;

  border-radius: 2px;
}