HTML5 canvas issue when I test on mobile's browser

Question

I'm working on an Animate cc project. to make an HTML5 canvas page. The issue will appear when I see the page on my mobile's browser. the issue is when I click any buttons in it then a blue transparent overlay will appear on all around of the screen and suddenly disappear. I searched about it on the internet but I couldn't find an answer to fix it. you can check the issue from the following address(please check it on your mobile browser):

My apps link

This is the codes that I used for it clicks event:

thisMc=this;

dialogsArr=[thisMc.ivanDialog,thisMc.akilDialog,thisMc.xiaDialog,thisMc.maxDialog,thisMc.mariaDialog,thisMc.observeTxt];
//disapear dialogs
function disapearDialogs()
{
    dialogsArr[0].alpha=0;
    dialogsArr[1].alpha=0;
    dialogsArr[2].alpha=0;
    dialogsArr[3].alpha=0;
    dialogsArr[4].alpha=0;
    dialogsArr[5].alpha=0;
}
disapearDialogs();
dialogsArr[5].alpha=1;

//persons events
thisMc.ivanBtn.on('click', function()
{
    createjs.Sound.stop();
    disapearDialogs();

    createjs.Sound.play('my_name_is_ivan');
    dialogsArr[0].alpha=1;
    stage.update();
});

thisMc.akilBtn.on('click', function()
{
    createjs.Sound.stop();
    disapearDialogs();

    createjs.Sound.play('my_name_is_akil');
    dialogsArr[1].alpha=1;
    stage.update();
});

thisMc.xiaBtn.on('click', function()
{
    createjs.Sound.stop();
    disapearDialogs();

    createjs.Sound.play('my_name_is_xia');
    dialogsArr[2].alpha=1;
    stage.update();
});

thisMc.maxBtn.on('click', function()
{
    createjs.Sound.stop();
    disapearDialogs();

    createjs.Sound.play('my_name_is_max');
    dialogsArr[3].alpha=1;
    stage.update();
});

thisMc.mariaBtn.on('click', function()
{
    createjs.Sound.stop();
    disapearDialogs();

    createjs.Sound.play('my_name_is_maria');
    dialogsArr[4].alpha=1;
    stage.update();
});

I wondered if anyone knows how to fix this issue. Please let me know if you know anything about it.

Thank you very much.

Tom