OVERRIDING PARENT THEME FILES
You can not only target individual style declarations via the style sheet but also override entire components of the parent theme.
For every theme file present in the parent directory, WordPress will check whether a corresponding file is present in the child theme and if so, use that one instead. This means that a
header.php file in the child theme will override its equivalent in the parent folder.
So, if you don’t like something about a page’s layout, just copy the respective file, implement your changes, and upload it to the child theme’s folder. The modifications will then appear in the child theme, while the original file will remain untouched.
WORKING WITH TEMPLATE FILES
We’ve learned that we can overwrite any file in the parent theme by placing a copy in the child theme’s folder and customizing it. However, using files that exist only in the child theme is also possible. Template files are a good example of this.
Let’s say we want to build a full-width page template for our child theme. Our theme does not lend itself to the full-screen presentation, but let’s do it anyway for demonstration purposes, shall we?
To create a full-width page in Oppi you have to create a custom page template. Let’s start with the page template.
For our custom page template, we simply copy
page.php from the parent theme, rename it to
page-full-width.php and place it in the Child theme’s root folder.