style.css

*{
    margin:0; padding:0;
}
body{
    font-family: Helvetica, sans-serif;
}
.vertical_align{
    height: 100%;
    width: 0;
    vertical-align: middle;
    display: inline-block;
}

/* game controls and start */

#gameInto{
    position: absolute;
    top: 0;
    left: 0;
    height: 100%;
    width: 100%;
    background: rgba(0,0,0,0.7);
    color: #ffffff;
    text-align: center;
    /* display: none; */
}

.game_into_container{
    vertical-align: middle;
    display: inline-block;
    margin: auto;
}
.game_into_container li{
    float: left;
    width: 200px;
    list-style: none;
    text-align: left;
}
.game_intro_container__block li{
    float: none;
}
.game_intro_container__block-button{
    background: none;
    border: 1px solid #fff;
    color: #fff;
    padding: 5px 20px;
    font-size: 20px;
    margin-top: 20px;
    transition: 1s;
}
.game_intro_container__block-button:hover{
    background: #fff;
    color: #333;
}

/* game over */

#gameOver{
    position: absolute;
    top: 0;
    left: 0;
    height: 100%;
    width: 100%;
    background: rgba(0,0,0,0.7);
    text-align: center;
    display: none;
}
.game_over_container{
    display: inline-block;
    vertical-align: middle;
}

#gameOver h3{
    color: #ff0000;
    font-size: 30px;
}

#gameOver button{
    background: none;
    color: #ff0000;
    font-size: 20px;
    padding: 5px 15px;
    border: 1px solid #ff0000;
    transition: 1s;
}
#gameOver button:hover{
    background: #ff0000;
    color: #000000;
}

/* health bar */
#healthBarContainer{
    position: absolute;
    z-index: 1;
    bottom: 0;
    left: 0;
    width: 100%;
    background: #fefefe;
    padding: 3px 5px;
}
#healthBarContainer p{
    display: inline-block;
    font-weight: 200;
}
#healthBarContainer .health_bar{
    display: inline-block;
    width: 500px;
    height: 40px;
    vertical-align: middle;
    background: #3d3d3d

}
#healthBarContainer .health_bar span{
    display: inline-block;
    height: 100%;
    width: 100%;
    background: #ff0000;
}