Upon scaling down an element that previously overflowed its container, I noticed that margin: 0 auto no longer centers the element as expected. Interestingly, even using transform-origin: center center did not fix this issue. It seems that the auto margins are applied before scaling, rather than after (which was my initial assumption).
After some experimentation, I found that the only way to center the element within its container is by using absolute positioning:
position: absolute;
transform: translateX(-50%) scale(0.5, 0.5);
left: 50%;
While this technique is commonly used, it's crucial to place the translateX function before the scale function as they are executed in a specific order.
Below is a code snippet demonstrating the issue (also available on CodePen: https://codepen.io/liranh85/pen/qVewQp)
.container {
border: 3px solid black;
width: 500px;
height: 200px;
margin: 0 auto;
position: relative;
}
.scaled {
background-color: blue;
width: 600px;
/* width: 400px; */
height: 100%;
transform: scale(0.5, 0.5);
/* transform: translateX(-50%) scale(0.5, 0.5); */
margin: 0 auto;
/* position: absolute;
left: 50%; */
}<div class="container">
<div class="scaled"></div>
</div>Key observations:
- Auto margins do not center the element when its width exceeds that of its container.
- Centering is possible when the scaled element has a width smaller than the container (e.g., using
width: 400px). - Absolutely positioning allows for centering the element in this scenario.
Some ponderings:
- Has anyone else encountered this issue?
- Is absolute positioning the optimal method for centering such elements?
- Can it be affirmed that auto margins are ineffective in centering such elements?