Center td.posters container

I could use a little css/flex assistance. I have been working on making the avatar of the original poster larger than the rest of the avatars and have figured everything out except how to center td.posters

I have used the method described here How to increase avatars size on Latest without making them blurred and modified it work with the original rather than latest. Here is my css:

td > a:first-child > img:first-child {
    height: 50px;
    width: 50px;
    margin-right: 3px;
}
  
td.posters {
    display: flex;
    align-items: center;
    margin-right: 25px;

  img.avatar {
    height: 25px;
    width: 25px;
  }
}

.topic-list .posters a:first-child .avatar.latest:not(.single) {
    top: 1px;
    bottom: 1px;
}

.topic-list td.posters {
        height: 54px;
}

Below I marked what I want to be centered between the dashed arrows. Here’s a link to my site.

I tried increasing the height of td.containers, but that only works on categories where I’m using the topic previews, in other categories where that is turned off it makes the spacing too large. I could target those categories to reduce the height but would prefer not to if there is an easier way. Thanks!

You may wish to hire someone experienced with CSS to assist you?