Tree view structure CSS node position issue

Question

CSS:-

body {
  font-family: Calibri, Segoe, "Segoe UI", "Gill Sans", "Gill Sans MT",
    sans-serif;
}

/* It's supposed to look like a tree diagram */
.tree,
.tree ul,
.tree li {
  list-style: none;
  margin: 0;
  padding: 0;
  position: relative;
}

.tree {
  margin: 0 0 1em;
  text-align: center;
}
.tree,
.tree ul {
  display: table;
}
.tree ul {
  width: 100%;
}
.tree li {
  display: table-cell;
  padding: 0.5em 0;
  vertical-align: top;
}
/* _________ */
.tree li:before {
  outline: solid 1px #666;
  content: "";
  left: 0;
  position: absolute;
  right: 0;
  top: 0;
}
.tree li:first-child:before {
  left: 50%;
}
.tree li:last-child:before {
  right: 50%;
}

.tree code,
.tree span {
  border: solid 0.1em #666;
  border-radius: 0.2em;
  display: inline-block;
  margin: 0 0.2em 0.5em;
  padding: 0.2em 0.5em;
  position: relative;
}
/* If the tree represents DOM structure */
.tree code {
  font-family: monaco, Consolas, "Lucida Console", monospace;
}

/* | */
.tree ul:before,
.tree code:before,
.tree span:before {
  outline: solid 1px #666;
  content: "";
  height: 0.5em;
  left: 50%;
  position: absolute;
}
.tree ul:before {
  top: -0.5em;
}
.tree code:before,
.tree span:before {
  top: -0.55em;
}

/* The root node doesn't connect upwards */
.tree > li {
  margin-top: 0;
}
.tree > li:before,
.tree > li:after,
.tree > li > code:before,
.tree > li > span:before {
  outline: none;
}

Please find this link Sample.

I am new to CSS.

The CSS for the below image is given in the above Sample link for the image shown below.

My issue is that 'body' cell and 'head' cell should be equidistant from the 'html' cell.

Right now 'body' cell is closer to the 'html' cell.

What should I modify in the CSS code?

Please see the image