I'm trying to build my web portfolio through GitHub Pages, and everything works as expected when I test it locally. But, when I commit to GitHub and test it, I am getting weird behavior like this:


But, I also get the correct behavior, especially if I reload the page.

What causes this weird jumping?
.item-list {
overflow: hidden;
text-align: center;
margin: 0 0 0 -24px;
}
.item-list li {
display: inline-block;
margin: 0 0 25px 24px;
vertical-align: top;
font-size: 0;
}
.item {
text-align: center;
width: 270px;
margin: 0 auto;
}
.item .image {
position: relative;
}
.item .image img {
min-width: auto;
max-width: 100%;
height: auto;
border-radius: 50%;
}
.item .hover {
display: none;
height: 100%;
left: 0;
position: absolute;
top: 0;
width: 100%;
background: #6abb84;
opacity: 0.9;
border-radius: 50%;
behavior: url(css/PIE.htc);
}
.item .hover.active {
display: block;
}
.item .item-content {
position: relative;
display: table-cell;
vertical-align: middle;
height: 270px;
z-index: 400;
padding: 0 30px;
}
.item a {
text-decoration: none;
}
.item .item-content h4 {
display: block;
background: url(../images/bg_white_border.gif) no-repeat 50% 100%;
color: #fff;
text-transform: uppercase;
font-family: 'novecentosanswide';
font-weight: bold;
font-size: 14px;
line-height: 16px;
padding: 0 0 20px;
text-align: center;
margin: 0 0 15px;
}
.item .item-content p {
color: #fff;
text-align: center;
display: block;
font-size: 15px;
line-height: 17px;
}
/*contact*/
.clear {
clear: both;
}
.images_holder {
float: left;
margin: 5px 130px 0 0;
width: 370px;
}
.images_holder img {
width: 100%;
height: auto;
display: inline;
}
<ul id="container" class="item-list">
<li class="item web key">
<div class="image ">
<img src="images/dungeon_mobile.png" alt="" />
<div class="hover">
<a class="fancybox" rel="gallery1" href="#portfolio_1">
<div class="item-content">
<h4>Dungeon Mobile</h4>
<p>2D RPG Mobile Game Currently Under Development</p>
</div>
</a>
</div>
</div>
</li>
</ul>
Website reference: https://panoskikas.github.io/
Repo: https://github.com/PanosKikas/PanosKikas.github.io