ne0kaz

<div class="container">
   <div class="div">Div</div>
   <div class="buttons">
      <button>Button1</button>
      <button>Button2</button>
   </div>
</div>

.container{
   display: flex;
   align-items: center;
  justify-content: center:
}
.buttons{
   display: flex;
   justify-content: space-between;
   align-items: flex-end;
   position: absolute;
   top: 0;
   left: 0;
   bottom: 0;    /* не обязательно*/
   right: 0;    /* не обязательно*/
   height: 100vh;
   width: 100vw;