body {
    margin: 0;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: gainsboro;
}

.loader {
    width: 4.3em;
    height: 9.8em;
    font-size: 10px;
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-between;
    animation: rotating 2s linear infinite;
}

@keyframes rotating {
    0%, 90% {
        transform: rotate(0);
    }
    
    100% {
        transform: rotate(0.5turn);
    }
}

.loader::after {
    content: '';
    position: absolute;
    width: 0.2em;
    height: 4.8em;
    background-color: deepskyblue;
    top: 1em;
    animation: flow 2s linear infinite;
}

@keyframes flow {
    10%, 100% {
        transform: translateY(3.2em);
    }
}

.top,
.bottom {
    width: 3.5em;
    height: 3.5em;
    border-style: solid;
    border-color: saddlebrown;
    border-width: 0.2em 0.2em 0.6em 0.6em;
    border-radius: 50% 100% 50% 30%;
    position: relative;
    overflow: hidden;
}

.top {
    transform: rotate(-45deg);
}

.bottom {
    transform: rotate(135deg);
}

.top::before,
.bottom::before {
    content: '';
    position: absolute;
    width: inherit;
    height: inherit;
    background-color: deepskyblue;
    animation: 2s linear infinite;
}

.top::before {
    border-radius: 0 100% 0 0;
    animation-name: drop-sand;
}

@keyframes drop-sand {
    to {
        transform: translate(-2.5em, 2.5em);
    }
}

.bottom::before {
    border-radius: 0 0 0 35%;
    transform: translate(2.5em, -2.5em);
    animation-name: fill-sand;
}

@keyframes fill-sand {
    to {
        transform: translate(0, 0);
    }
}