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// Find all YouTube videos
var $allVideos = $("iframe[src*='//www.youtube.com']"),
    // The element that is fluid width
    $fluidEl = $(".main-content");
// Figure out and save aspect ratio for each video
$allVideos.each(function() {
  $(this)
    .data('aspectRatio', this.height / this.width)
    // and remove the hard coded width/height
    .removeAttr('height')

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The HTML
The HTML code sets the YouTube video ID, styles the video size (width and height), and lists the Youtube URL parameters if needed.

The CSS
In the two videos used as examples, the picture ratio is 16:9, which returns the sddefault.jpg thumbnail with horizontal black bands. To hide them when showing this thumbnail, the background-position property is set with the center value, while setting the picture size inlined in the HTML div tag, like style="width:500px;height:281px;". This way, it is possible to show different video sizes on the same page.

The play icon, which tells the users the content is not a mere picture, is added in a layer on top of the thumbnail with an opacity transition to highlight it. We are using a data URI base64-encoded png here (from IconFinder), which saves an HTTP request and works down to IE8.

Vanilla JavaScript Implementation
With no dependency and the fastest implementation, the vanilla JavaScript version uses the smallest DOM ready code I could find.

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window.onload = function(){
    var tab = document.getElementsByTagName('table');
    tab[0].className = 'table table-hover';
}

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var element = document.getElementById('sidebar');
var trigger = document.getElementById('js-toggle-sidebar'); // or whatever triggers the toggle

trigger.addEventListener('click', function(e) {
    e.preventDefault();
    element.classList.toggle('sidebar-active'); // or whatever your active class is
});

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Для Safari (iPhone / IPod / IPad) и Android браузера

<meta name="format-detection" content="telephone=no">

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// Use Gists to store code you would like to remember later on
console.log(window); // log the "window" object to the console

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jQuery
$(window).scroll(function() {    
	var scroll = $(window).scrollTop();

	if ( (scroll >= 100) && ($(window).width() > '991') ) {
		$(".b-scrollHeader").addClass("js-show");
	} else {
		$(".b-scrollHeader").removeClass("js-show");
	}
});

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CSS
pointer-events:none

or jQuery
$('.overlay').click(function(e){

	$(".target").trigger(e);

});

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test
test
test
test