backgroundChanger.css

* {
    margin: 0;
    padding: 0;
}

body {
    background-color: #808080;
}

.container {
    text-align: center;
    position: absolute;
    width: 100%;
    top: 50%;
    transform: translateY(-50%);
}

.text {
    background-color: rgba(0, 0, 0, 0.582);
    color: white;
    font-family: sans-serif;
    font-size: 3rem;
    padding: 10px;
    text-align: center;
    text-shadow: 0 0 5px rgb(0, 0, 0);
}

span {
    color: rgb(3, 2, 41);
    text-shadow: 0 0 5px white;
    font-weight: bold;
    cursor: pointer;
}

button {
    padding: 10px;
    border: 3px solid #000;
    border-radius: 6px;
    font-size: 1rem;
    background-color: rgb(255, 255, 255);
    color: #000;
    margin-top: 20px;
    outline: none;
    cursor: pointer;
    transition: all 0.3s;
}

button:hover {
    background-color: #000;
    color: #fff;
}

.copied {
    position: absolute;
    color: white;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 2rem;
    animation-name: getBigger;
    animation-duration: 900ms;
    background-color: rgba(0, 0, 0, 0.575);
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
}

@keyframes getBigger {
    from {
        font-size: 2rem;
    }
    to {
        font-size: 8rem;
    }
}