Showing iteration loop ngFor

I have a problem displaying my windows of discussion (cf image). My two windows should be aligned at the bottom and not at the top.

Here is my HTML:

<div class="chat-window-container">
   <window-item
       *ngFor="let thread of (windows ? windows.slice(0,2):[])"
       [thread]="thread">
   </window-item>
</div>

And the HTML for window-item :

<div class="chat-window" id="chat-window-{{thread.id}}"
  *ngIf="thread.isOpen">
  <div class="panel-container">
  </div>
</div>

Here is my CSS:

 chat-window[_ngcontent-c4] {
    position: relative;
    display: inline-block;
    margin-left: 0px;
    margin-right: 40px;
 }

 .chat-window {
   margin-left: 20px;
   margin-right: 20px;
   width: 336px;
   padding: 0px;
   right: 262px;
   bottom: 0;
   position: fixed;
   float: right;
 }

/////////////////////
UPDATE :

CSS :

.chat-window-container {
  display: flex;
  justify-content: center;
  align-items: baseline;
}