.float-parent-element { 
    width: 50%; 
} 
.float-child-element { 
    float: left; 
    width: 50%;
    border-width: 10px;
    border-color: black;
}
.float-details-element {
    border: 1px solid darkgreen;
    background-color: lightgreen;
    margin: 5px;
    padding: 1rem;
    height: 100%;
}

.parent {
  border: 1px solid black;
  margin: 1rem;
  padding: 2rem 2rem;
  text-align: left;
}
.child {
  display: inline-block;
  border: 1px solid red;
  padding: 1rem 1rem;
  vertical-align: top;
}
