.btn-fab {
  border: 1px solid #000;
  border-radius: 30px;
}
.btn-pizza-1 {
  background-color: #fff;
}
.btn-pizza-2 {
  background-color: #fff;
  background-image: linear-gradient(to bottom, transparent 49%, #000 49%, #000 51%, transparent 51%);
}
.btn-pizza-3 {
  background-color: #fff;
  background-image: 
    linear-gradient(to right, transparent 49%, #000 49%, #000 51%, transparent 51%),
    linear-gradient(to bottom,transparent 49%, #000 49%, #000 51%, transparent 51%);
}
.btn-pizza-4 {
  background-color: #fff;
  background-image: 
    linear-gradient(to right, transparent 49%, #000 49%, #000 51%, transparent 51%),
    linear-gradient(to bottom,transparent 49%, #000 49%, #000 51%, transparent 51%),
    linear-gradient(45deg,transparent 49%, #000 49%, #000 51%, transparent 51%),
    linear-gradient(135deg,transparent 49%, #000 49%, #000 51%, transparent 51%);
}
<div class="panel-body no_padding padding_bottom_top_list" style="display: inline-block;">
                <div class="list-group">
                    <div class="list-group-item list_group_item_padding">
                        <div class="row-action-primary padding_right_list" style="text-align:center">
                            <button class="btn btn-fab  green_status2 btn-pizza-1" style="width:60px; height:60px; font-size:30px; color:white; "></button>
                            </br>
                            <button class="btn btn-fab  green_status2 btn-pizza-2" style="width:60px; height:60px; font-size:30px; color:white; "></button>
                            </br>
                            <button class="btn btn-fab  green_status2 btn-pizza-3" style="width:60px; height:60px; font-size:30px; color:white; "></button>
                            </br>
                            <button class="btn btn-fab  green_status2 btn-pizza-4" style="width:60px; height:60px; font-size:30px; color:white; "></button>
                            </br>
                        </div>
                    </div>
                </div>
            </div>
 
It would be easier with svg
– MarceloBoni
Take a look here https://www.w3schools.com/graphics/svg_inhtml.asp might help you, teach you how to make circles and lines with svg.
– LeAndrade
https://codepen.io/ShubhangiRaj/pen/MYZOZo ou https://codepen.io/dsmoore/details/fiwAl
– MarceloBoni