如何使用CSS固定列的高度和宽度

<div class="container">
  <div class="row">
    <!-- BEGIN PRODUCTS -->
    <div
      class="col-md-3 col-sm-6 col-equal"
      *ngFor="let p of (titres | sort: titreSort)"
    >
      <span class="thumbnail">
        <img src="{{ p.URL_couv }}" alt="{{ p.id }}" />
        <h4>
          <label style="display: block; width: 600px;"
            >{{ p.titre }} n° {{ p.numero }}</label
          >
        </h4>

        <p></p>
        <hr class="line" />
        <div class="row">
          <div class="col-md-6 col-sm-6">
            <p class="price"></p>
          </div>
          <div class="col-md-6 col-sm-6"></div>
        </div>
      </span>
    </div>
  </div>
</div>

   

.side-body {
  margin-left: 310px;}
   
.right {
  float: right;
  border-bottom: 2px solid #4b8e4b;
}

.thumbnail {
  -webkit-transition: all 0.5s;
  transition: all 0.5s;
}
.thumbnail:hover {
  opacity: 1;
  box-shadow: 0px 0px 10px #41d834;
}
.line {
  margin-bottom: 5px;
}

@media (max-width: 768px) {
  .col-equal {
    margin: auto;
    display: flex;
    display: -webkit-flex;
    flex-wrap: wrap;
  }
}