.hidden {
    color: transparent;
}

body {
    background: url(./fondo.png);
    background-size: cover;
    color: #fff;
    font-family: 'SF Pixelate', sans-serif;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.espacio-top{
    padding-top: 2.5rem;
}

#wordContainer {
    margin-top: 20px;
}

.letter {
    margin: 0 7px;
    position: relative;
    text-align: center;
}

.letter::after{
    content: ' ';
    display: block;
    position: absolute;
    left: 0;
    width: 100%;
    height: 1px;
    background-color: #fff;
    min-width: 12px;
}

button {
    --color: #0080f8;
    font-family: inherit;
    display: inline-block;
    width: 8em;
    height: 2.6em;
    line-height: 2.5em;
    margin: 5px;
    position: relative;
    overflow: hidden;
    border: 2px solid var(--color);
    transition: color .3s;
    z-index: 1;
    font-size: 19px;
    border-radius: 6px;
    font-weight: 500;
    color: var(--color);
}
   
button:before {
    content: "";
    position: absolute;
    z-index: -1;
    background: var(--color);
    height: 150px;
    width: 200px;
    border-radius: 50%;
}
   
button:hover {
    color: rgb(255, 255, 255);
    cursor: pointer;
}
   
button:before {
    top: 100%;
    left: 100%;
    transition: all .8s;
}
   
button:hover:before {
    top: -30px;
    left: -30px;
}