html, body, div, span, applet, object, iframe,h1, h2, h3, h4, h5, h6, p, blockquote, pre,a, abbr, acronym, address, big, cite, code,del, dfn, em, img, ins, kbd, q, s, samp,small, strike, strong, sub, sup, tt, var,
b, u, i, center,dl, dt, dd, ol, ul, li,fieldset, form, label, legend,table, caption, tbody, tfoot, thead, tr, th, td,article, aside, canvas, details, embed, 
figure, figcaption, footer, header, hgroup, menu, nav, output, ruby, section, summary,time, mark, audio, video {
	margin: 0;
	padding: 0;
	border: 0;
	font-size: 100%;
	font: inherit;
	vertical-align: baseline;
}
.contenido-block {max-width:648px; margin:0px;}
.contenido-block .imagen{margin:0px; text-align:center; display:block;}
.contenido-block img {width:100%}
.contenido-block .imagen2{display: none;}

@media only screen and (max-width: 375px) {
	.contenido-block .imagen{display: none;}
	.contenido-block .imagen2{display:block; margin:0px; text-align:center;}
}