Unnecessary horizontal scroll bar, incorrect CSS style

Where: https://www.freecodecamp.org/learn/responsive-web-design/basic-html-and-html5/ , may affect other pages too.
All pages: no
Bug: unnecessary page horizontal scroll bar, incorrect CSS style. It is not the pre scrollbar, its the page scroll bar.
Env: Ubuntu. It happen in this browsers: Chrome, Chromium, Firefox.

Related to this settings:

.row {
    margin-left: -15px;
    margin-right: -15px;
<div class="intro-layout-container">
	<div class="row"></div>

Issue opened, fixed, closed.