A CodePen by Dom Sammut. Simple CSS Loading animation - I just wanted to create a loading animation for a web app using CSS. Nothing to fancy.

index.html

<div class="loading-container">
    <div class="loading"></div>
    <div id="loading-text">loading</div>
</div>

script.js

/*
Dom Sammut 2014
***************
Web: www.domsammut.com
Twitter: www.twitter.com/domsammut

*/

style.css

body {background: #333333;}
@-moz-keyframes rotate-loading {
    0%  {transform: rotate(0deg);-ms-transform: rotate(0deg); -webkit-transform: rotate(0deg); -o-transform: rotate(0deg); -moz-transform: rotate(0deg);}
    100% {transform: rotate(360deg);-ms-transform: rotate(360deg); -webkit-transform: rotate(360deg); -o-transform: rotate(360deg); -moz-transform: rotate(360deg);}
}

@-o-keyframes rotate-loading {
    0%  {transform: rotate(0deg);-ms-transform: rotate(0deg); -webkit-transform: rotate(0deg); -o-transform: rotate(0deg); -moz-transform: rotate(0deg);}
    100% {transform: rotate(360deg);-ms-transform: rotate(360deg); -webkit-transform: rotate(360deg); -o-transform: rotate(360deg); -moz-transform: rotate(360deg);}
}

@-webkit-keyframes rotate-loading {
    0%  {transform: rotate(0deg);-ms-transform: rotate(0deg); -webkit-transform: rotate(0deg); -o-transform: rotate(0deg); -moz-transform: rotate(0deg);}
    100% {transform: rotate(360deg);-ms-transform: rotate(360deg); -webkit-transform: rotate(360deg); -o-transform: rotate(360deg); -moz-transform: rotate(360deg);}
}

@keyframes rotate-loading {
    0%  {transform: rotate(0deg);-ms-transform: rotate(0deg); -webkit-transform: rotate(0deg); -o-transform: rotate(0deg); -moz-transform: rotate(0deg);}
    100% {transform: rotate(360deg);-ms-transform: rotate(360deg); -webkit-transform: rotate(360deg); -o-transform: rotate(360deg); -moz-transform: rotate(360deg);}
}

@-moz-keyframes loading-text-opacity {
    0%  {opacity: 0}
    20% {opacity: 0}
    50% {opacity: 1}
    100%{opacity: 0}
}


@-o-keyframes loading-text-opacity {
    0%  {opacity: 0}
    20% {opacity: 0}
    50% {opacity: 1}
    100%{opacity: 0}
}

@-webkit-keyframes loading-text-opacity {
    0%  {opacity: 0}
    20% {opacity: 0}
    50% {opacity: 1}
    100%{opacity: 0}
}

@keyframes loading-text-opacity {
    0%  {opacity: 0}
    20% {opacity: 0}
    50% {opacity: 1}
    100%{opacity: 0}
}

.loading-container,
.loading {
    height: 100px;
    position: relative;
    width: 100px;
    border-radius: 100%;
}

.loading-container { margin: 40px auto; }

.loading {
    border: 2px solid transparent;
    border-color: transparent #fff transparent #FFF;
    -moz-animation: rotate-loading 1.5s linear 0s infinite normal;
    -moz-transform-origin: 50% 50%;
    -o-animation: rotate-loading 1.5s linear 0s infinite normal;
    -o-transform-origin: 50% 50%;
    -webkit-animation: rotate-loading 1.5s linear 0s infinite normal;
    -webkit-transform-origin: 50% 50%;
    animation: rotate-loading 1.5s linear 0s infinite normal;
    transform-origin: 50% 50%;
}

.loading-container:hover .loading {
    border-color: transparent #E45635 transparent #E45635;
}

.loading-container:hover .loading,
.loading-container .loading {
    -webkit-transition: all 0.5s ease-in-out;
    -moz-transition: all 0.5s ease-in-out;
    -ms-transition: all 0.5s ease-in-out;
    -o-transition: all 0.5s ease-in-out;
    transition: all 0.5s ease-in-out;
}

#loading-text {
    -moz-animation: loading-text-opacity 2s linear 0s infinite normal;
    -o-animation: loading-text-opacity 2s linear 0s infinite normal;
    -webkit-animation: loading-text-opacity 2s linear 0s infinite normal;
    animation: loading-text-opacity 2s linear 0s infinite normal;
    color: #ffffff;
    font-family: "Helvetica Neue", "Helvetica", "Arial", sans-serif;
    font-size: 10px;
    font-weight: bold;
    margin-top: 45px;
    opacity: 0;
    position: absolute;
    text-align: center;
    text-transform: uppercase;
    top: 0;
    width: 100px;
}