.ct-rectangle { width: 100%; display: flex; justify-content: center; align-items: center; }

.title { display: inline-block;  }
.title li { text-align: center; display: inline-block; width: 220px; border: 2px solid grey;  }
.support img { display: inline-block; width: 210px; height: 300px; margin-left: auto; margin-right: auto; margin-top: 7.5px; 
box-shadow: 0px 2px 8px black;
}
.support { display: inline-block; width: 225px; height: 315px; background-color: darkgoldenrod;  }
.link { display: inline-block;  }
.link li {text-align: center; display: inline-block; width: 220px; border: 2px solid grey; }
.link a { color: grey; text-decoration: none;  }

#ecartement { margin-left: 100px; margin-right: 100px;}
  
  <div class="ct-rectangle">
   
    <div class="title">
        <li>Notre équipe</li>
        <li id="ecartement">Réalisations</li>
        <li>Nos valeurs</li>
    </div></div>
    <br>
    <div class="ct-rectangle">
    <div class="img">
        <div class="support"><img src="/CSS/test.png" alt=""></div>
        <div id="ecartement" class="support"><img src="/CSS/test.png" alt=""></div>
        <div class="support"><img src="/CSS/test.png" alt=""></div>
        </div></div>
    <br>
    <div class="ct-rectangle">
    <div class="link">
        <li><a href="">Voir</a></li>
        <li id="ecartement"><a href="">Voir</a></li>
        <li><a href="">Voir</a></li>
        </div></div>
    
</div>