style.css

body {
    margin: 0;
    font-family: "Trebuchet MS", Helvetica, sans-serif;
}

.title {
    display: block;
    color: white;
    text-align: center;
    font-size: large;
    background-color: #00BCD4;
    margin: 0;
    padding: 12;
}

.sub {
    background-color: #80DEEA;
    font-size: medium;
    padding: 8;
}

.tree{
    width: fit-content;
    display: inline-block;
    margin: 10px;
}

.container{
    float: left;
}

#status, #operation {
    display: inline-block;
}

#statusMessages{
    width: 100vh
}

#statusContainer, #operationContainer {
    padding: 10px;
    margin: 20px;
    margin-right: 0px;
    background-color: #def4fe;
    border-radius: 10px;
    width: fit-content;
    display: inline-block;
}

.deque {
  padding: 20px;
  padding-right: 60px;
  width: fit-content;
  display: inline-block;
}

.dequeNode, .headNode {
  font-size: 11px;
  /*color: #666;*/
  color: #000;
  -webkit-transition: all 0.5s;
  padding: 10px;
  padding-top: 5px;
  padding-bottom: 5px;
  margin: 5px;
  text-align: center;
  border-radius: 5px;
  border: solid 1px #ccc;
  display: inline-block;
}

.headNode {
  background-color: #e3e3e3;
}

/*
.dequeNode:hover {
  -webkit-transition: all 0.5s;
  background-color: #c8e4f8;
}
*/
.tree ul {
    padding-top: 20px; position: relative;
    
    transition: all 0.5s;
    -webkit-transition: all 0.5s;
    -moz-transition: all 0.5s;
}

.tree li {
    float: left; text-align: center;
    list-style-type: none;
    position: relative;
    padding: 20px 5px 0 5px;
    
    transition: all 0.5s;
    -webkit-transition: all 0.5s;
    -moz-transition: all 0.5s;
}

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

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

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

.tree li:first-child::before, .tree li:last-child::after{
    border: 0 none;
}
.tree li:last-child::before{
    border-right: 1px solid #ccc;
    border-radius: 0 5px 0 0;
    -webkit-border-radius: 0 5px 0 0;
    -moz-border-radius: 0 5px 0 0;
}
.tree li:first-child::after{
    border-radius: 5px 0 0 0;
    -webkit-border-radius: 5px 0 0 0;
    -moz-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{
    border: 1px solid #ccc;
    padding: 5px 10px;
    text-decoration: none;
    color: #000;
    font-family: arial, verdana, tahoma;
    font-size: 11px;
    display: inline-block;
    
    border-radius: 5px;
    -webkit-border-radius: 5px;
    -moz-border-radius: 5px;
    
    transition: all 0.5s;
    -webkit-transition: all 0.5s;
    -moz-transition: all 0.5s;
}
/*
.tree li div:hover, .tree li div:hover+ul li div {
    background: #c8e4f8; color: #000; border: 1px solid #94a0b4;
}

.tree li div:hover+ul li::after, 
.tree li div:hover+ul li::before, 
.tree li div:hover+ul::before, 
.tree li div:hover+ul ul::before{
    border-color:  #94a0b4;
}
*/

.null-elt {
    background-color: #e3e3e3;
}