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, font, 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 {
 margin: 0;
 padding: 0;
 border: 0;
 outline: 0;
 font-size: 100%;
 vertical-align: baseline;
 background: transparent;
 }
body {
 line-height: 1;
 }
ol, ul {
 list-style: none;
 }
blockquote, q {
 quotes: none;
 }
blockquote:before, blockquote:after, q:before, q:after {
 content: '';
 content: none;
 }
<em>/* No olvides definir estilos para focus */</em>
 :focus {
 outline: 0;
 }
<em>/* No olvides resaltar de alguna manera el texto insertado/borrado */</em>
ins {
 text-decoration: none;
 }
 del {
 text-decoration: line-through;
 }
<em>/* En el código HTML es necesario añadir cellspacing="0" */</em>
 table {
 border-collapse: collapse;
 border-spacing: 0;
 }