demo.css

html, body {
    padding: 0;
    margin: 0;
    height: 100%;
    font-size: 16px;
    background: #000;
    color: #fff;
    font-family: 'Source Sans Pro'; 
}

h1 {
    font-size: 2.8em;
    font-weight: 700;
    letter-spacing: -1px;
    margin: 0.6rem 0; 
}
h1 > span {font-weight: 300; }
h2 {
    font-size: 1.15em;
    font-weight: 300;
    margin: 0.3rem 0; 
}
main {
    width: 95%;
    max-width: 1000px;
    margin: 4em auto;
    opacity: 0; 
}
main.loaded {transition: opacity .25s linear;opacity: 1; }
main header {width: 100%; }
main header > div {width: 50%; }
main header > .left, main header > .right {height: 100%; }
main .loaders {
    width: 100%;
    box-sizing: border-box;
    display: flex;
    flex: 0 1 auto;
    flex-direction: row;
    flex-wrap: wrap;
}
main .loaders .loader {
    box-sizing: border-box;
    display: flex;
    flex: 0 1 auto;
    flex-direction: column;
    flex-grow: 1;
    flex-shrink: 0;
    flex-basis: 25%;
    max-width: 25%;
    height: 200px;
    align-items: center;
    justify-content: center;
}