<div class="container">
     <div class="item item1">1</div>
     <div class="item item2">2</div>
     <div class="item item3">3</div>
     <div class="item item4">4</div>
     <div class="item item5">5</div>
     <div class="item item6">6</div>
     <div class="item item7">7</div>
     <div class="item item8">8</div>
     <div class="item item9">9</div>
     <div class="item item10">10</div>
   </div>
   <style>
     .container {
       display: grid;

       grid-template-columns:
        300px 300px 300px;

       grid-template-rows: 300px;

       grid-auto-rows: 75px 150px;
     }
   </style>