styles.css

@import url("https://fonts.googleapis.com/css?family=Comfortaa");

html,
body {
    margin: 0;
    overflow: hidden;
    height: 100%;
    width: 100%;
    position: relative;
    font-family: 'Comfortaa', cursive;
}

#container {
    width: 100%;
    height: 100%;
}

#container #score {
    position: absolute;
    top: 20px;
    width: 100%;
    text-align: center;
    font-size: 10vh;
    transition: -webkit-transform 0.5s ease;
    transition: transform 0.5s ease;
    transition: transform 0.5s ease, -webkit-transform 0.5s ease;
    color: #333344;
    -webkit-transform: translatey(-200px) scale(1);
    transform: translatey(-200px) scale(1);
}

#container #game {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
}

#container .game-over {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 85%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

#container .game-over * {
    transition: opacity 0.5s ease, -webkit-transform 0.5s ease;
    transition: opacity 0.5s ease, transform 0.5s ease;
    transition: opacity 0.5s ease, transform 0.5s ease, -webkit-transform 0.5s ease;
    opacity: 0;
    -webkit-transform: translatey(-50px);
    transform: translatey(-50px);
    color: #333344;
}

#container .game-over h2 {
    margin: 0;
    padding: 0;
    font-size: 40px;
}

#container .game-ready {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-around;
}

#container .game-ready #start-button {
    transition: opacity 0.5s ease, -webkit-transform 0.5s ease;
    transition: opacity 0.5s ease, transform 0.5s ease;
    transition: opacity 0.5s ease, transform 0.5s ease, -webkit-transform 0.5s ease;
    opacity: 0;
    -webkit-transform: translatey(-50px);
    transform: translatey(-50px);
    border: 3px solid #333344;
    padding: 10px 20px;
    background-color: transparent;
    color: #333344;
    font-size: 30px;
}

#container #instructions {
    position: absolute;
    width: 100%;
    top: 16vh;
    left: 0;
    text-align: center;
    transition: opacity 0.5s ease, -webkit-transform 0.5s ease;
    transition: opacity 0.5s ease, transform 0.5s ease;
    transition: opacity 0.5s ease, transform 0.5s ease, -webkit-transform 0.5s ease;
    opacity: 0;
}

#container #instructions.hide {
    opacity: 0 !important;
}

#container.playing #score,
#container.resetting #score {
    -webkit-transform: translatey(0px) scale(1);
    transform: translatey(0px) scale(1);
}

#container.playing #instructions {
    opacity: 1;
}

#container.ready .game-ready #start-button {
    opacity: 1;
    -webkit-transform: translatey(0);
    transform: translatey(0);
}

#container.ended #score {
    -webkit-transform: translatey(6vh) scale(1.5);
    transform: translatey(6vh) scale(1.5);
}

#container.ended .game-over * {
    opacity: 1;
    -webkit-transform: translatey(0);
    transform: translatey(0);
}

#container.ended .game-over p {
    transition-delay: 0.3s;
}