hide irrelevant content in a web page

hide_irrelevant_content_in_a_web_page.css

/* 
 * site: https://www.oxfordlearnersdictionaries.com/
 */
#ad_btmslot_a, iframe {
  visibility: hidden;
}

/* 
 * site: https://learning.oreilly.com/ 
 */

.sbo-site-nav, 
.sbo-nav-top, 
.interface-control-btns, 
.subscribe-nag,
.sbo-nav-bottom,
.pagefoot {
    visibility: hidden;
}

/* 
 * site: https://www.javatpoint.com/
 */

.onlycontent > div:nth-child(1),
#right,
#leftad,
div[data-refresh-time],
ins[data-ad-client] {
    visibility: hidden;
}