main.css

body {
    padding: 0px;
    margin: 0px;
    background-color: #f3f3f3;
    font-family: 'Roboto', 'Helvetica', sans-serif;
    
}
.preloader {
    position: relative;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-flow: column;
    width: 100vw;
    height: 100vh;
    background-color: #171717;
    z-index:1; 
    transition: all 0.5s ease-out
}
.wrapper {
    position: absolute;
    width: 100%;
    height: 100%;
    opacity: 1;
    z-index: 10; 
    background-color: white;
}
.preloader .preload-text {
    color: #f3f3f3;
    font-size: 28px;
    font-weight: 300;
}

.preloader .blocks {
    position: relative;
    width: 70px;
    height: 70px;
    animation: rotate 5s ease-in-out infinite;
}
.preloader .blocks .block {
    position: absolute;
    width: 30px;
    height: 40px;
    border-radius: 4px;
    background-color: #FFCE00;
    transition: all 0.5s ease-out
}
.opacity {
    opacity: 0;
    transition: all 2.5s ease-out;
}
.preloader .blocks .block:nth-child(1) {
    top: 0;
    left: 40px;

}
.preloader .blocks .block:nth-child(2) {
    top:  0px;
    left: 0px;
    
}
.preloader .blocks .block:nth-child(3) {
    top: 50px;
    left: 0px;
    
}
@keyframes rotate {
    0% {
        transform: rotate(0%)
    }
    100% {
        transform: rotate(360deg);
    }
}