Make Spotify embeds ('Spotify Play Button') fit the width of your responsive layout.

respondify.js

$(document).ready(function() {

	/* Make Spotify fit initial layout */
	respondify();

});


$(window).resize(function() {

	/* Make Spotify fit layout on resize */
	respondify();

});


function respondify() {

	// Make the Spotify playlist embed fit the layout.
	// Spotify wants the height of the embed to be the width + 80px,
	// When the embed is narrower than 210px, Spotify wants the height to be 80px (art work and title only).

	$('body').find('iframe[src*="embed.spotify.com/?uri="]').each(function() {
		var w = $(this).parent(1).width();
		var h_offset = 80;

		$(this).css('width', w + 'px');

		if (w < 210) {
			$(this).css('height', h_offset + 'px');			
		}
		else {
			$(this).css('height', (w + 80) + 'px');
		}

		$(this).attr('src',$(this).attr('src'));
	});

}

Improves upon:
http://codepen.io/jbasoo/pen/gDkoc

Get your Spotify embed code here:
https://developer.spotify.com/technologies/widgets/spotify-play-button/