body {
    margin:0;
    padding:0;
    height: 100vh;
    z-index: -1;
    
    /* Prevent scroll bars from appearing*/
    overflow: hidden;

    /* stop text being selected*/
    -webkit-touch-callout: none;
    -webkit-user-select: none;
     -khtml-user-select: none; 
       -moz-user-select: none; 
        -ms-user-select: none; 
            user-select: none; 

}

#game_window {
    margin:0;
    background-color: black;
    height: 100vh;
    width: 100%;
    padding:0;

    display:flex;
    flex-flow: row wrap;
    justify-content: flex-start;

    position: relative;

    /* Prevent scroll bars from appearing*/
    overflow: hidden;
}

#left_paddle {
    background-color: white;
    position: absolute;
    left: 5rem;
    top: 50%;
    height: 6rem;
    width: 1rem;
}

#right_paddle {
    background-color: white;
    position: absolute;
    right: 5rem;
    top: 50%;
    height: 6rem;
    width: 1rem;
}

#center_line {
    background-color: white;
    position: absolute;
    width: 0.6rem;
    left:50%;
    height: 100vh;
}

#ball {
    background-color: white;
    position: absolute;
    left: 40%;
    top: 50%;
    width: 1rem;
    height:1rem;
    border-radius: 50%;
}

.score {
    font-family: 'Times New Roman', Times, serif;
    font-size:4rem;
    color: whitesmoke;
    position: absolute;
    top: 1rem;

}

#player_score {
    left: 35%;
}

#computer_score {
    right:35%;
}

#title {
    font-size: 5rem;
    position: absolute;
    color: white;
    font-family: 'Times New Roman', Times, serif;
    width: 100%;
    text-align: center;

}

.difficulty_button {
    font-size:3rem;
    color: black;
    background-color: white;
    padding: 1rem;
    margin-top: 2rem;

    /* Prevents hitbox being covered by title*/
    z-index: 1;
}

#easy:hover {
    padding-top: 1.3rem;
    padding-bottom: 1.3rem;
    margin-top: 1.7rem;
    margin-bottom: -0.3rem;
}
#medium:hover {
    padding-top: 1.3rem;
    padding-bottom: 1.3rem;
    margin-top: 1.7rem;
    margin-bottom: -0.3rem;
}
#hard:hover {
    padding-top: 1.3rem;
    padding-bottom: 1.3rem;
    margin-top: 1.7rem;
    margin-bottom: -0.3rem;
}

#difficulties {
    margin: auto;
    margin-left: 22%;
    display: flex;
    flex-flow: column wrap
}

#instruction {
    color: white;
    font-size: 2rem;
    margin-top:40%;
}

#game_end_message {
    color: white;
    font-size: 3rem;
    margin: auto;

}

.gameButton {
    border-radius: 5%;
    background-color: rgba(200,200, 200, 0.2);
    border: solid rgba(255,255,255, 0.2) 0.1px;
    text-align: center;
    height: 50%;
    margin:0;
    z-index: 1;
    color: rgba(255,255,255, 0.2);
    font-size: 3rem;
}

#gameButtonContainer {
    width: 40%;
    height: 100%;
    flex-flow: column nowrap;
    align-items: stretch;
}


.full-screen {
    vertical-align: middle;
    box-sizing: border-box;
    display: inline-block;
    border: .1em solid white;
    width: 1em;
    height: 1em;
    position: absolute;
    left:0;
    top:0;
    background-color: black;
    font-size: 5rem;
  }
  .full-screen:before, .full-screen:after {
    content: '';
    background: #000000;
    position: absolute;
  }
  .full-screen:before {
    width: .333em;
    height: 1em;
    left: .233em;
    top: -.1em;
  }
  .full-screen:after {
    width: 1em;
    height: .333em;
    top: .233em;
    left: -.1em;
  }
  
  .full-screen:hover{
      font-size: 6rem;
  }