there are some issues in this family tree I made

I have this good family tree but the problem is that the page is funcy like everything is on top of each other how can I fix it (it's better to try it in a coding app because CSS doesn't work here (if it does I don't know))

<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>family tree</title>
<link rel="stylesheet" href="style.css">
<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/css/bootstrap.min.css"

rel="stylesheet" id="bootstrap-css">

• great great great grand father
  • great great grand father
    • great grand father
      • grand mother
        • grand father
        • mother
        • father
          
        • child
        • child
        • child
        • child
        • child
        • child
      • father
        
      • mother
    • child
    • child
    • child
    • child
    • child
  • father
  • mother
    
  • child
  • child
• grand father

grand mother

                                        </li>
                                    </ul>
                                </li>
                            </ul>
                        </li>
                    </ul>
                </li>
                <li>
                    <a href="#">father</a>
                    <ul>
                        <li><a href="#">Grand Child</a></li>
                        <li>
                            <a href="#">Grand Child</a>
                            <ul>
                                <li>
                                    <a href="#">Great Grand Child</a>
                                </li>
                                <li>
                                    <a href="#">Great Grand Child</a>
                                </li>
                                <li>
                                    <a href="#">Great Grand Child</a>
                                </li>
                            </ul>
                        </li>
                        <li><a href="#">Grand Child</a></li>
                    </ul>
                </li>
            </ul>
        </li>
    </ul>
</div>
    </div>
</div> </body> </html>

    * {
        margin: 0;
        padding: 0;
    }
    
    .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 a {
        border: 1px solid #ccc;
        padding: 5px 10px;
        text-decoration: none;
        color: #666;
        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 a:hover,
    .tree li a:hover+ul li a {
        background: #c8e4f8;
        color: #000;
        border: 1px solid #94a0b4;
    }
    
    .tree li a:hover+ul li::after,
    .tree li a:hover+ul li::before,
    .tree li a:hover+ul::before,
    .tree li a:hover+ul ul::before {
        border-color:
            #94a0b4;
    }

Using Mermaid JS, to obtain a graph, It may also be helpful to see the shape of the abstraction used to create the tree structure.

As you can see in code -mermaid code- section, With a one-dimensional flat set, it is possible to express node connections. _{(Since enlarging the graph makes no practical sense, I did not choose to enlarge any further. A tree with two or three generations is sufficient.)}

I hope all this gives an idea.

PS: On the additional question in the comments, I've edited the answer. When using Mermaid, using the syntax in the example code --> 2 [ Aidem ], You can use the same name on different nodes. For additional questions, reviewing and trying the documentation may get you closer to the answer.

graph TD

Root --> Liven
Root --> Aidem

Root --> Dimitri --> Oleg
Root --> Olga --> Oleg

Liven --> Milna
Aidem --> Milna
Milna --> Harmi

Oleg --> Harmi

Harmi --> 2[Aidem]
Mina  --> 2[Aidem]
Root --> Mina