Blame for style.css

#particles-js {
    position: absolute;
    width: 100%;
    height: 100%;
    z-index: -1;
}
.container {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    position: relative;
    z-index: 1;
}
h1 {
    font-weight: 400;
    letter-spacing: 0.5em;
    text-align: center;
}