#to-top-button {
    display: none;
    position: fixed;
    bottom: 16px;
    right: 16px;
    z-index: 1;
    border: none;
    outline: none;
    cursor: pointer;
    padding: 6px 8px;
    border-radius: 10px;

    color: white;
    background-color: var(--main-color);
    filter: opacity(50%);
}

#to-top-button:hover ,
#to-top-button:focus {
    background-color: var(--main-color-hover);
}