How to fix column heigth and width using CSS : i'm developping an e-commerce web site where all the products are displayed in the same page in "cols"
the problem is that i couldn't fix the col width or height using CSS                                                                                                                                       

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-html -->

    <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>


<!-- end snippet -->

this is my code 
 
and this is how the products are showing 

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/12k2K.png


and this is my CSS code 

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-css -->

   

    .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;
      }
    }


<!-- end snippet -->

Any help please ? 
Thank you 
