SOURCE

<div class="wrapper">
    <header class="main-header">
        <h1 class="page-title">Single Element CSS Loaders</h1>
    </header>
    <main class="main-content">
        <section class="loader-section">
            <div class="loader-spin">
                <div class="threes">
                    <div class="three three-1"></div>
                    <div class="three three-2"></div>
                    <div class="three three-3"></div>
                </div>
            </div>
        </section>
      
    </main>
</div>

* {
    box-sizing: border-box;
}
:root {
    position: relative;
    min-height: 100%;
    font-family: 'Roboto', sans-serif;
    font-size: 10px;
}
:root body {
    height: 100%;
    min-height: .1rem;
}
body {
    margin: 0;
    background-color: #2c3e50;
    font-size: 1.6rem;
}
a {
    text-decoration: none;
}
h1,
h2,
h3 {
    font-family: 'Roboto', sans-serif;
    font-weight: normal;
}


.wrapper {
    display: -ms-grid;
    display: grid;
    -ms-grid-columns: 100%;
    grid-template-columns: 100%;
    -ms-grid-rows: 6rem 100% 7rem;
    grid-template-rows: 6rem 100% 7rem;
    grid-template-areas: 'header' 'main' 'footer';
    min-height: 100vh;
}
.main-header {
    display: -webkit-box;
    display: -ms-flexbox;
    display: flex;
    -webkit-box-align: center;
    -ms-flex-align: center;
    align-items: center;
    -webkit-box-pack: center;
    -ms-flex-pack: center;
    justify-content: center;
    padding: 0 2rem;
    grid-area: header;
}
.page-title {
    margin: 0;
    color: #fff;
    font-size: 2.2rem;
    line-height: 3rem;
}
.main-content {
    display: -webkit-box;
    display: -ms-flexbox;
    display: flex;
    -ms-flex-flow: row wrap;
    flex-flow: row wrap;
    margin: 0 auto;
    width: 100%;
    max-width: 96rem;
    padding: 5rem 2rem;
    grid-area: main;
}
.loader-section {
    display: -webkit-box;
    display: -ms-flexbox;
    display: flex;
    -webkit-box-orient: vertical;
    -webkit-box-direction: normal;
    -ms-flex-direction: column;
    flex-direction: column;
    -webkit-box-align: center;
    -ms-flex-align: center;
    align-items: center;
    -webkit-box-pack: justify;
    -ms-flex-pack: justify;
    justify-content: space-between;
    -webkit-box-flex: 0;
    -ms-flex: 0 1 33.3333%;
    flex: 0 1 33.3333%;
    padding: 2rem 1rem;
}



.loader-spin {
    position: relative;
    width: 6rem;
    height: 6rem;
}

.threes {
    display: -webkit-box;
    display: -ms-flexbox;
    display: flex;
    -webkit-box-align: center;
    -ms-flex-align: center;
    align-items: center;
    -webkit-box-pack: justify;
    -ms-flex-pack: justify;
    justify-content: space-between;
    width: 100%;
    height: 100%;
}
.threes .three {
    display: -webkit-inline-box;
    display: -ms-inline-flexbox;
    display: inline-flex;
    width: 30%;
    height: 30%;
    border-radius: 100%;
    background-color: #fff;
    -webkit-animation: three 1.5s infinite ease-in-out both;
    animation: three 1.5s infinite ease-in-out both;
}
.threes .three-1 {
    -webkit-animation-delay: -320ms;
    animation-delay: -320ms;
}
.threes .three-2 {
    -webkit-animation-delay: -160ms;
    animation-delay: -160ms;
}

@-webkit-keyframes three {
    0%, 80%, 100% {
        -webkit-transform: scale(0);
        transform: scale(0);
    }
    40% {
        -webkit-transform: scale(1);
        transform: scale(1);
    }
}
@keyframes three {
    0%, 80%, 100% {
        -webkit-transform: scale(0);
        transform: scale(0);
    }
    40% {
        -webkit-transform: scale(1);
        transform: scale(1);
    }
}