<div class="audio-recorder">
  <p [hidden]="canRecord">Audio recording <br> only supported in modern versions of Chrome, Firefox and Safari.</p>
  <mat-spinner class="send-audio-spinner" [diameter]="72" [strokeWidth]="2" [hidden]="!isSending"></mat-spinner>
  <div [hidden]="!canRecord || isSending">
    <button type="button" id='btnRecord' (click)="recordingToggle()" class="btn-circle-xl">
      <mat-icon [hidden]="isRecording" aria-label="Quit cross icon">fiber_manual_record</mat-icon>
      <mat-icon [hidden]="!isRecording" aria-label="Quit cross icon">stop</mat-icon>
    </button>

    <div id="button-wrapper">
      <button type="button" id='btnSend' (click)="sendRecording()" [disabled]="!recordingAvailable" class="btn-circle">
        <i class="fa fa-paper-plane"></i>
      </button>
      <button type="button" id='btnPlay' [disabled]="!recordingAvailable" (click)="playStop()" class="btn-circle">
        <i class="fa fa-play"></i>
      </button>
    </div>

    <audio id='audioPlayer'></audio>
    <canvas class="audio-visualiser" id="audio-recorder-visualiser"></canvas>
  </div>
</div>
<div class="audio-recorder">
  <p [hidden]="canRecord">Audio recording <br> only supported in modern versions of Chrome, Firefox and Safari.</p>
  <mat-spinner class="send-audio-spinner" [diameter]="72" [strokeWidth]="2" [hidden]="!isSending"></mat-spinner>
  <div [hidden]="!canRecord || isSending">
    <button type="button" id='btnRecord' (click)="recordingToggle()" class="btn-circle-xl">
      <mat-icon [hidden]="isRecording" aria-label="Quit cross icon">fiber_manual_record</mat-icon>
      <mat-icon [hidden]="!isRecording" aria-label="Quit cross icon">stop_rounded</mat-icon>
    </button>

    <div id="button-wrapper">
      <button type="button" id='btnSend' (click)="sendRecording()" [disabled]="!recordingAvailable" class="btn-circle">
        <i class="fa fa-paper-plane"></i>
      </button>
      <button type="button" id='btnPlay' [disabled]="!recordingAvailable" (click)="playStop()" class="btn-circle">
        <i class="fa fa-play"></i>
      </button>
    </div>

    <audio id='audioPlayer'></audio>
    <canvas class="audio-visualiser" id="audio-recorder-visualiser"></canvas>
  </div>
</div>
Use rounded icon for stop button
LOOKS: Use rounded icon for stop button
