Looking for a way to center a box on a website I'm designing? Instead of aligning it based on existing centering, use the following HTML / CSS code to ensure that the white box is perfectly centered on the page.
.loading {
position: fixed;
z-index: 999;
height: 2em;
width: 2em;
overflow: show;
margin: auto;
top: 0;
left: 0;
bottom: 0;
right: 0;
}
/* Transparent Overlay */
.loading:before {
content: '';
display: block;
position: fixed;
top: 0;
left: 0;
width: 100%;
height: 100%;
background-color: rgba(0,0,0,0.3);
}
.centrediv {
height: 200px;
width: 800px;
background-color: white;
border: 1px solid black;
}<div class="loading"><div class="centrediv">Your Content Here</div></div>