how to place 2 divs side by side using css code example

Example 1: how to align two divs side by side

.wrapper {
    display: flex;
    flex-wrap: wrap;
}

.wrapper>div {
    flex: 1 1 150px;
    height: 500px;
}

Example 2: div side by side

.float-container {
    border: 3px solid #fff;
    padding: 20px;
}

.float-child {
    width: 50%;
    float: left;
    padding: 20px;
    border: 2px solid red;
}
<div class="float-container">

  <div class="float-child">
    <div class="green">Float Column 1</div>
  </div>
  
  <div class="float-child">
    <div class="blue">Float Column 2</div>
  </div>
  
</div>