title: Angular: strange mat-sidenav-container behaviour in Firefox
body: <p>Firefox does not &quot;accept&quot; the width set in mat-sidenav when I first open the website. Only after reloading it adjusts the mat-sidenav how it should be.</p>
  <p><a href="https://i.stack.imgur.com/aYHmp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/aYHmp.png" alt="![enter image description here" /></a></p>
  <p>CSS:</p>
  <pre><code>mat-sidenav {
      padding: 16px;
      width: 100px;
      background-color: blue;
  }
  </code></pre>
  <p>html</p>
  <pre><code>&lt;mat-sidenav-container&gt;
      &lt;mat-sidenav #sidenav  fixedInViewport=&quot;true&quot; opened=&quot;true&quot;&gt;
          &lt;mat-nav-list&gt;
  
          &lt;a mat-list-item routerLink=&quot;/home&quot; routerLinkActive=&quot;active-list-item&quot;&gt;
              &lt;mat-icon matListIcon&gt;home&lt;/mat-icon&gt;
              &lt;h3 matLine&gt;Home&lt;/h3&gt;
          &lt;/a&gt;
          &lt;a mat-list-item routerLink=&quot;/account&quot; routerLinkActive=&quot;active-list-item&quot;&gt;
              &lt;mat-icon matListIcon&gt;folder_open&lt;/mat-icon&gt;
              &lt;h3 matLine&gt;Accounts&lt;/h3&gt;
          &lt;/a&gt;
          &lt;a mat-list-item routerLink=&quot;/about&quot; routerLinkActive=&quot;active-list-item&quot;&gt;
              &lt;mat-icon matListIcon&gt;info&lt;/mat-icon&gt;
              &lt;h3 matLine&gt;About&lt;/h3&gt;
          &lt;/a&gt;
          &lt;/mat-nav-list&gt;
      &lt;/mat-sidenav&gt;
      &lt;mat-sidenav-content&gt;
          &lt;router-outlet&gt;&lt;/router-outlet&gt;
      &lt;/mat-sidenav-content&gt;
  &lt;/mat-sidenav-container&gt;
  </code></pre>
  <p>If I remove the width everything works fine. I have no problems with chrome or edge.</p>
  <p>I already tried the autosize parameter in mat-sidenav-container which solves the problem but brings similar strange behaviours when adding hover on mat-sidenav.</p>
  <p>This is how it should look like:</p>
  <p><a href="https://i.stack.imgur.com/A72qo.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/A72qo.png" alt="enter image description here" /></a></p>