body {
    height: 100vh;
    width: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    padding: 0;
    margin: 0;
    font-family: sans-serif;
    background: linear-gradient(rgba(0,0,0,.5), rgba(0,0,0,.5)100%), url(img/back.jpg);
    background-size: cover;
}

#main-play-area {    
    height: 600px;
    width: 600px;
}

.par {
    text-align: center;
    color: white;
    font-family: Arial;
    margin-top: 110px;
}

.game-instructions {
    position: relative;
    color: white;
    font-size: 15pt;
    text-align: center;
    top: 3rem;
}

.start-button {
    position: relative;
    color: white;
    top: 5rem;
    text-align: center;
    cursor: pointer;
}

.player-shooter {
    position: relative;
    height: 80px;
    width: 90px;
    left: 20px;
    top: 250px;
}

.laser {
    position: relative;
    width: 40px;
    height: 30px;
}

.alien {
    height: 80px;
    width: 90px;
    position: relative;
}

.alien-transition {
    opacity: 1;
    transition: opacity 1.5s ease-in-out;
}

.dead-alien {
    height: 60px;
    width: 70px;
    position: relative;
    opacity: 0;
}

.rodape p{
    text-align: center;
    font-size: 10pt;
    font-family: verdana;
    color: #808080;    
}

footer a {
    color: #808080;
}

footer a:hover {
    color: purple;
    font-weight: bolder;    
}