body {
margin: 0;
padding: 0;
width:100vw;
height: 100vh;
}
.loader-wrapper {
width: 100%;
height: 100%;
position: absolute;
top: 0;
left: 0;
background-color: #242f3f;
display:flex;
justify-content: center;
align-items: center;
}
.loader {
display: inline-block;
width: 30px;
height: 30px;
position: relative;
border: 4px solid #Fff;
animation: loader 2s infinite ease;
}
.loader-inner {
vertical-align: top;
display: inline-block;
width: 100%;
background-color: #fff;
animation: loader-inner 2s infinite ease-in;
}

@keyframes loader {
0% { transform: rotate(0deg);}
25% { transform: rotate(180deg);}
50% { transform: rotate(180deg);}
75% { transform: rotate(360deg);}
100% { transform: rotate(360deg);}
}

@keyframes loader-inner {
0% { height: 0%;}
25% { height: 0%;}
50% { height: 100%;}
75% { height: 100%;}
100% { height: 0%;}
}