#FootballContainer 
{
    position: fixed;
    width: calc(100% - 100px);
    height: 100vh;
    z-index:1; 
    pointer-events:none;
}
#FootballContainer > div 
{
    position: absolute;
    width: 50px;
    height: 50px;
    
    /* We use the following properties to apply the fade and drop animations to each Football.
       Each of these properties takes two values. These values respectively match a setting
       for fade and drop.
    */
    -webkit-animation-iteration-count: infinite, infinite;
    -webkit-animation-direction: normal, normal;
    -webkit-animation-timing-function: linear, ease-in;
}

/* This CSS rule is applied to all img elements directly inside div elements which are
   directly inside the FootballContainer div. In other words, it matches the 'img' elements
   inside the FootballDivs which are created in the createAFootball() function.
*/
#FootballContainer > div > img {
     position: absolute;
     width: 50px;
     height: 50px;

    /* We use the following properties to adjust the clockwiseSpin or counterclockwiseSpinAndFlip
       animations on each Football.
       The createAFootball function in the Football.js file determines whether a Football has the 
       clockwiseSpin or counterclockwiseSpinAndFlip animation.
    */
     -webkit-animation-iteration-count: infinite;
     -webkit-animation-direction: alternate;
     -webkit-animation-timing-function: ease-in-out;
     -webkit-transform-origin: 30% -100%;
}


/* Hides a Football towards the very end of the animation */
@-webkit-keyframes fade
{
    /* Show a Football while into or below 95 percent of the animation and hide it, otherwise */
    0%   { opacity: 1; }
    95%  { opacity: 1; }
    100% { opacity: 0; }
}


/* Makes a Football fall from -300 to 600 pixels in the y-axis */
@-webkit-keyframes drop
{
    /* Move a Football to -300 pixels in the y-axis at the start of the animation */
    0%   { -webkit-transform: translate(-50px, -50px); }
    /* Move a Football to 600 pixels in the y-axis at the end of the animation */
    100% { -webkit-transform: translate(0px, 100vh); }
}

/* Rotates a Football from -50 to 50 degrees in 2D space */
@-webkit-keyframes clockwiseSpin
{
    /* Rotate a Football by -50 degrees in 2D space at the start of the animation */
    0%   { -webkit-transform: rotate(-50deg); }
    /*  Rotate a Football by 50 degrees in 2D space at the end of the animation */
    100% { -webkit-transform: rotate(50deg); }
}


/* Flips a Football and rotates it from 50 to -50 degrees in 2D space */
@-webkit-keyframes counterclockwiseSpinAndFlip 
{
    /* Flip a Football and rotate it by 50 degrees in 2D space at the start of the animation */
    0%   { -webkit-transform: scale(-1, 1) rotate(50deg); }
    /* Flip a Football and rotate it by -50 degrees in 2D space at the end of the animation */
    100% { -webkit-transform: scale(-1, 1) rotate(-50deg); }
}