Vertically centering button using css

.container {
  background: lightblue;
  display: table;
  width:100%;
}
        
input[type=button] {    
  display: block;
  width: 50%;
  margin: 0 auto;
}
        
.button-wrapper {
  background: darkorange;
  display: table-cell;
  vertical-align: middle;
}

<div class='container'>
    
  <div>some line with text</div>
  <div>another line with text</div>    
    
  <div class='button-wrapper'>
    <input type="button" value="submit"  />
  </div>
    
</div>

.container {
  background: bisque;
  display: flex;
  width: 100%;
}

.container>div {
  flex-grow: 1;
}

.button-wrapper {
  background: chocolate;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

input[type=button] {
  display: block;
  width: 50%;
  margin: 0 auto;
  flex-shrink: 1;
}

<div class='container'>

  <div>
    <p>some line with text</p>
    <p>another line with text</p>
  </div>

  <div class='button-wrapper'>
    <input type="button" value="submit" />
  </div>

</div>