.tree {
  display: flex;
  align-items: center;
  justify-content: center;
}

.tree ul {
  padding-top: 20px;
  position: relative;
  transition: all 0.5s;
  display: flex;
}

.tree li,
.tree child {
  list-style-type: none;
  flex-wrap: nowrap;
  text-align: center;
}

.tree child {
  position: relative;
  padding: 20px 5px 0 5px;
  transition: all 0.5s;
}

.tree child::before,
.tree child::after {
  content: '';
  position: absolute;
  top: 0;
  right: 50%;
  border-top: 1px solid #ccc;
  width: 50%;
  height: 20px;
}

.tree child::after {
  right: auto;
  left: 50%;
  border-left: 1px solid #ccc;
}

.tree child:only-child::after,
.tree child:only-child::before {
  display: none;
}

.tree child:only-child {
  padding-top: 0;
}

.tree child:first-child::before,
.tree child:last-child::after {
  border: 0 none;
}

.tree child:last-child::before {
  border-right: 1px solid #ccc;
  border-radius: 0 5px 0 0;
}

.tree child:first-child::after {
  border-radius: 5px 0 0 0;
}

.tree ul ul::before {
  content: '';
  position: absolute;
  top: 0;
  left: 50%;
  border-left: 1px solid #ccc;
  width: 0;
  height: 20px;
}

.tree li div.content {
  border: 1px solid #ccc;
  padding: 5px 10px;
  text-decoration: none;
  font-family: arial, verdana, tahoma, serif;
  font-size: 11px;
  display: inline-block;
  border-radius: 5px;
  transition: all 0.5s;
  color: #fff;
  font-weight: bold;
}

.tree ul.empty::before {
  content: none;
}

body {
  counter-reset: section;
}

.tree li div.content::before {
  font-size: 12px;
  counter-increment: section;
  content: attr(data-id) " " attr(data-finished-time);
}


div.content {
  transition: all 2s ease-in-out;
  will-change: transform;
}

div.center {
  text-align: center;
}


child label {
  display: block;
  padding-left: 15px;
  text-indent: -15px;
  margin-bottom: 5px;
}

child label input {
  width: 13px;
  height: 13px;
  padding: 0;
  margin:0;
  vertical-align: bottom;
  position: relative;
  top: 2px;
  left: 5px;
  overflow: hidden;
}
