CSS - margin fusion - example 5

Here, margin declared on both elements

by Julien Roche

HTML

<div class="main">
  <div class="main__child" style="margin-bottom: 30px;">Height: 75px + margin bottom 30px</div>
  <div class="main__child" style="margin-top: 20px;">Height: 75px  + margin top 20px</div>
</div>
<br />
<p>
  <span>Element height: </span>
  <span id="heightResult"></span>
  <span>px !== with expected 200px</span>
</p>

CSS

html, body {
  height: 100%;
}

body {
  align-items: center;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.main {
  background-color: orange;
  border: none;
  display: inline-block;
  margin: 0 0 0 0;
  padding: 0 0 0 0;
  width: 350px;
}

.main__child {
  background-color: black;
  color: white;
  height: 75px;
}

Babel + JSX

let heightResultElement = document.querySelector('#heightResult');
let mainElement = document.querySelector('.main');

function updateHeight() {
	let bounds = mainElement.getBoundingClientRect();
  heightResultElement.innerText = bounds.height;
}

let ro = new ResizeObserver(updateHeight);
ro.observe(mainElement);