:root {
    --loader-color: #515a5a;
    --back-color: #e9eaea;
    --time: 5s;
    --size: 3px;
}

.loader {
    background-color: var(--main-color);
    overflow: hidden;
    width: 100%;
    height: 100%;
    position: fixed;
    top: 0;
    left: 0;
    display: flex;
    align-items: start;
    align-content: center;
    justify-content: flex-start;
}

.loader__element {
    height: var(--size);
    width: 100%;
    background: var(--back-color);

}

.loader__element:before {
    content: '';
    display: block;
    background-color: var(--loader-color);
    height: var(--size);
    width: 0;
    animation: getWidth var(--time) ease-in infinite;
}

@keyframes getWidth {
    100% {
        width: 100%;
    }
}