I have added your suggested code to style.css in the child directory but it doesn’t appear to have had any effect: –
/*
Theme Name: Twenty Sixteen Child
Description: Twenty Sixteen Child Theme
Author: DJP
Version: 1.0
Template: twentysixteen
*/
@import url('../twentysixteen/style.css');
#secondary {
display: none;
}
@media screen and (min-width: 56.875em) {
/*no sidebar expand center*/
.no-sidebar .content-area
{
float: left;
margin-right: -100%;
width: 100%;
}
.no-sidebar .site-content
{
padding: 0px;
}
.no-sidebar .entry-header, .no-sidebar .entry-content, .no-sidebar .entry-summary, .no-sidebar .entry-footer, .no-sidebar .comments-area, .no-sidebar .image-navigation, .no-sidebar .post-navigation, .no-sidebar .pagination, .no-sidebar .page-header, .no-sidebar .page-content, .no-sidebar .content-bottom-widgets
{
margin-right: 5%;
margin-left: 5%;
}
body.no-sidebar:not(.search-results) article:not(.type-page) .entry-content
{
margin-left: 25%;
width: 70%;
}
body.no-sidebar:not(.search-results) article:not(.type-page) .entry-footer
{
margin-left: 5%;
}
}
Am I overlooking something?