Absolutely or relatively positioned elements don't occupy its initial space in the document, so other elements behave as if it wasn't there.
I need this behavior, but with a sticky element.
I hope the code explains it all:
(also have it on JSFiddle)
const myDiv = document.querySelector('#container');
const tooltip = document.querySelector('#tooltip');
let showTooltip = false;
myDiv.addEventListener('click', () => {
showTooltip = !showTooltip;
if (showTooltip) {
tooltip.classList.add('shown');
} else {
tooltip.classList.remove('shown');
}
})
#container {
height: 19rem;
overflow-y: scroll;
}
.info {
background: lightblue;
padding: .5rem;
}
#tooltip {
background: gray;
position: sticky;
bottom: 0;
margin: 0 2rem;
opacity: 0;
padding: 1rem;
}
#tooltip.shown {
opacity: 1;
}
<div id="container">
<div class="content info">
Click in this div to hide/show the tooltip.
</div>
<div class="content">
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ex assumenda, quos, perspiciatis temporibus asperiores, corporis rerum veritatis veniam enim rem repellat doloribus a. Asperiores, perferendis voluptatem, quis non modi quibusdam!</p>
</div>
<div class="content">
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ex assumenda, quos, perspiciatis temporibus asperiores, corporis rerum veritatis veniam enim rem repellat doloribus a. Asperiores, perferendis voluptatem, quis non modi quibusdam!</p>
</div>
<div class="content">
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ex assumenda, quos, perspiciatis temporibus asperiores, corporis rerum veritatis veniam enim rem repellat doloribus a. Asperiores, perferendis voluptatem, quis non modi quibusdam!</p>
</div>
<div class="content">
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ex assumenda, quos, perspiciatis temporibus asperiores, corporis rerum veritatis veniam enim rem repellat doloribus a. Asperiores, perferendis voluptatem, quis non modi quibusdam!</p>
</div>
<div id="tooltip">
This tooltip should not occupy its initial space at the bottom of its parent div...
<br><br><br>
But yet its space is taken into consideration. Scroll down to see...
</div>
</div>
Note: using 'display' instead of 'position' as suggested in answers also doesn't work. It does prevent the tooltip of occupying space when not displayed, but when displayed it's space is still taken in consideration...