xolvio/pojo-observer

.flex-container {
  display: flex;
  border: 5px solid yellow;
  flex-direction: row;
  justify-content: space-between;
  height: 95vh;
}

.right{
  display: flex;
  border: 5px solid gray;
  flex-direction: column;
  justify-content: space-between;
  width: 55vw;
}

.file-tree {
  border: 5px solid red;
  width: 45vw;
  padding: 10px;
}

.file-tree ul {
  list-style-type:none;
  padding:0;
  margin:10px;
}

.file-tree ul li {
  list-style:none;
}

.file-tree_item {
  padding: 5px 0;
  border: 1px solid #fff
}

.file-tree_item.selected {
  background-color: #ccf;
  border: 1px solid #ccf
}

.file-tree_item:hover {
  cursor: pointer;
  border: 1px solid #889
}

.file-contents {
  border: 5px solid green;
  height: 100vw;
  padding: 10px;
}

.file-details {
  border: 5px solid blue;
  height: 25vw;
  padding: 10px;
}

.file-details ul {
  list-style-type:none;
  padding:0;
  margin:10px;
}

.file-details ul li {
  list-style:none;
}

.overlay {
  display: flex;
  position: absolute;
  top: 10px;
  left: 10px;
  bottom: 0;
  right: 0;
  width: 45vw;
  height: 100%;
  background-color: white;
  opacity: 0.6;
  align-items: center;
  justify-content: center;
  text-align: center;
  font-size: 40px;
}