How to Build a WordPress Theme from Scratch: the Basics

In this tutorial, we’ll explore WordPress theme file structure in depth, and learn how to create a basic WordPress theme from scratch.

In the first part of this series, we introduced WordPress theming, and the fundamental terminology relating to WordPress theme development. We covered templates, partials, template hierarchy, WordPress post types, the style.css stylesheet, WordPress filter and action hooks, WordPress loop, conditional tags, and we briefly took a look at a typical simple WordPress theme file structure.

Key Takeaways

• Start by setting up a bare minimum theme using an index.php and style.css file, ensuring WordPress recognizes your new theme.
• Integrate Bootstrap for responsive design and aesthetics, modifying template files to include Bootstrap’s HTML and CSS classes.
• Utilize the functions.php file to add custom functionality, enqueue styles and scripts, and manage WordPress hooks effectively.
• Customize the dynamic output of the header and navigation menus using WordPress hooks and conditionals to adapt to different page types.
• Ensure your theme is responsive and user-friendly on mobile devices by adjusting CSS and using media queries.

Creating the Bare Minimum Theme

The first thing we’ll do is install a plugin that will enable us to batch create WordPress posts and other content. This way, we’ll be able to quickly populate our development website without losing too much time. One plugin that serves this purpose is FakerPress by Gustavo Bordoni, available in the WordPress plugin repository.

We quickly install and activate the plugin via WP-CLI.

Now, when we log in to the admin dashboard, we’ll see that FakerPress is installed, and we can create all sorts of content in batch, including any custom post types we have.

Now, using this plugin, we’ll create some fake content. This is the result, using the default TwentySeventeen WordPress theme:

Now, we quickly dive in and set up a bare minimum theme that consists of the catch-all index.php file, and style.css, which we need for the WordPress templating system to recognize the theme:

<span>/*
</span><span>Theme Name: Botega Simple Theme
</span><span>Theme URI: https://botega.co.uk
</span><span>Author: Tonino Jankov
</span><span>Author URI: https://botega.co.uk
</span><span>Description: Basic WordPress theme for Sitepoint theme building tutorial
</span><span>Text Domain: bsimple
</span><span>Version: 1.0.0
</span><span>License: GNU General Public License v2 or later
</span><span>*/
</span>

This is the style.css, which consists only of meta CSS comments for now. These comments are required.

This is the index.php file. It will catch all the requests for now:

<span>/*
</span><span>Theme Name: Botega Simple Theme
</span><span>Theme URI: https://botega.co.uk
</span><span>Author: Tonino Jankov
</span><span>Author URI: https://botega.co.uk
</span><span>Description: Basic WordPress theme for Sitepoint theme building tutorial
</span><span>Text Domain: bsimple
</span><span>Version: 1.0.0
</span><span>License: GNU General Public License v2 or later
</span><span>*/
</span>

We now upload and activate the minimal theme we have. I activate it using WP-CLI:

The theme is now visible to WordPress, and is active:

We haven’t provided a screenshot, so the display in the backend is basic.

If we visit our website now in the browser, this is what we’ll see:

Obviously, we have work to do.

If we view the source code of the home page, we’ll see that the wp_head() function has outputted a lot of default WordPress tags in the

, like CSS, JavaScript, link and meta tags.

The bloginfo() function is used to output website information.

Our home page is empty, because we aren’t outputting anything inside the Loop — a pattern that WordPress uses in all of its templates to output content.

The Codex page about the Loop goes deep into details about it. A typical structure for the loop — which is based on PHP while control structure — looks like this:

<span><span><?php </span></span><span><span>/**
</span></span><span><span> *
</span></span><span><span> * <span>@package Botega_Scratch_Theme
</span></span></span><span><span> */
</span></span><span><span>?></span>
</span>
<span><span>
</span><span><span><span> <span><span><?php language_attributes(); ?></span></span>></span>
</span><span><span><span>></span>
</span>    <span><span><span><title>></title></span><span><?php bloginfo('name'); ?></span><span><span></span>></span>
</span>    <span><span><span><link> rel<span>="stylesheet"</span> href<span>="<span><?php bloginfo('stylesheet_url'); ?></span>"</span>></span>
</span>    <span><span><?php wp_head(); ?></span>
</span><span><span><span></span>></span>
</span><span><span><span>></span>
</span>
      <span><span><span><header>></header></span>
</span>         <span><span><span><h1 id="gt">></h1></span><span><?php bloginfo('name'); ?></span><span><span></span>></span>
</span>         <span><span><span><h3 id="gt">></h3></span><span><?php bloginfo('description'); ?></span><span><span></span>></span>
</span>      <span><span><span></span>></span>
</span>
        <span><span><?php </span></span><span>        <span>if ( have_posts() ) :
</span></span><span>            <span>/* Start the Loop */
</span></span><span>            <span>while ( have_posts() ) :
</span></span><span>                <span>the_post();
</span></span><span>            <span>endwhile;
</span></span><span>        <span>endif;
</span></span><span>        <span>?></span>
</span>
<span><span><span></span>></span>
</span></span></span></span></span></span></span></span></span></span></span></span>

We need to fill that while loop with content — or with content-outputting WordPress tags.

If we change our loop, by adding the_title(), the_excerpt(), and we add HTML markup and the_ID(), to look like this:

<span><span><?php </span></span><span><span>if ( have_posts() ) {
</span></span><span>    <span>while ( have_posts() ) {
</span></span><span>        <span>the_post();
</span></span><span>        <span>//
</span></span><span>        <span>// Post Content here
</span></span><span>        <span>//
</span></span><span>    <span>} // end while
</span></span><span><span>} // end if
</span></span><span><span>?></span>
</span></span>

We’ll now get a list of posts on our home page, with no style applied:

WordPress shows A blog page — an archive page for all the blog posts — by default.

If we now visit single post URL — something like http://my-website.com/2018/11/14/sapiente-ad-facilis-quo-repellat-quos/ — we’ll see something like this:

Our loop, albeit very crude, actually works.

Structuring Our Theme into Files and Applying Bootstrap Markup

We’ll now implement partials, like header.php and footer.php and various specialized templates, all using Twitter Bootstrap markup, so that we can style it more easily.

Starting with index.php, we replace all the content before and after the loop with get_header() and get_footer() functions:

    <span><span><?php </span></span><span>    <span>if ( have_posts() ) : while ( have_posts() ): the_post(); ?></span>
</span>
    <span><span><span><div> id<span>="post-<span><?php the_ID(); ?></span>"</span>>
        <span><span><span><h2 id="gt">></h2></span><span><?php the_title(); ?></span><span><span></span>></span>
</span>        <span><span><span><div> class<span>="post-excerpt"</span>><span><?php the_excerpt(); ?></span><span><span></span></span>
</div></span>></span>
</span>    <span><span><span></span></span></span></span>
</div></span>></span>
</span>
    <span><span><?php endwhile;
</span></span><span>    <span>endif;
</span></span><span>    <span>?></span>
</span></span></span>

This means we need to provide all that content in the partials we mentioned.

In line with what we said — that we’ll use Twitter Bootstrap theme — our header.php file will look like this:

<span><span><?php </span></span><span><span>/**
</span></span><span><span> *
</span></span><span><span> * <span>@package Botega_Scratch_Theme
</span></span></span><span><span> */
</span></span><span>
</span><span><span>get_header(); ?></span>
</span>
    <span><span><?php </span></span><span>    <span>if ( have_posts() ) : while ( have_posts() ): the_post(); ?></span>
</span>
    <span><span><span><div> id<span>="post-<span><?php the_ID(); ?></span>"</span>>
        <span><span><span><h2 id="gt">></h2></span><span><?php the_title(); ?></span><span><span></span>></span>
</span>        <span><span><span><div> class<span>="post-excerpt"</span>><span><?php the_excerpt(); ?></span><span><span></span></span>
</div></span>></span>
</span>    <span><span><span></span></span></span></span>
</div></span>></span>
</span>
    <span><span><?php endwhile;
</span></span><span>    <span>endif;
</span></span><span>    <span>?></span>
</span>
<span><span><?php get_footer(); ?></span>
</span></span></span></span>

Our footer.php file will look like this:

<span>/*
</span><span>Theme Name: Botega Simple Theme
</span><span>Theme URI: https://botega.co.uk
</span><span>Author: Tonino Jankov
</span><span>Author URI: https://botega.co.uk
</span><span>Description: Basic WordPress theme for Sitepoint theme building tutorial
</span><span>Text Domain: bsimple
</span><span>Version: 1.0.0
</span><span>License: GNU General Public License v2 or later
</span><span>*/
</span>

We are using Bootstrap classes in our HTML tags, and wp_head() and wp_footer() fire wp_head and wp_footer action hooks.

The next thing we’ll do is include the CSS and JavaScript from clean bootstrap template from startbootstrap.com, which comes with an MIT license, so we can freely use it. This way, our theme will come with predefined styles, responsiveness, and we’ll still be able to style it further.

functions.php

functions.php is a file that comes with any serious WordPress theme. This is a file that acts as a poor man’s plugin archive. It allows us to include any custom functionality in our theme.

We’ll firstly use this file to include Bootstrap and our bootstrap theme’s styles and scripts:

<span><span><?php </span></span><span><span>/**
</span></span><span><span> *
</span></span><span><span> * <span>@package Botega_Scratch_Theme
</span></span></span><span><span> */
</span></span><span><span>?></span>
</span>
<span><span>
</span><span><span><span> <span><span><?php language_attributes(); ?></span></span>></span>
</span><span><span><span>></span>
</span>    <span><span><span><title>></title></span><span><?php bloginfo('name'); ?></span><span><span></span>></span>
</span>    <span><span><span><link> rel<span>="stylesheet"</span> href<span>="<span><?php bloginfo('stylesheet_url'); ?></span>"</span>></span>
</span>    <span><span><?php wp_head(); ?></span>
</span><span><span><span></span>></span>
</span><span><span><span>></span>
</span>
      <span><span><span><header>></header></span>
</span>         <span><span><span><h1 id="gt">></h1></span><span><?php bloginfo('name'); ?></span><span><span></span>></span>
</span>         <span><span><span><h3 id="gt">></h3></span><span><?php bloginfo('description'); ?></span><span><span></span>></span>
</span>      <span><span><span></span>></span>
</span>
        <span><span><?php </span></span><span>        <span>if ( have_posts() ) :
</span></span><span>            <span>/* Start the Loop */
</span></span><span>            <span>while ( have_posts() ) :
</span></span><span>                <span>the_post();
</span></span><span>            <span>endwhile;
</span></span><span>        <span>endif;
</span></span><span>        <span>?></span>
</span>
<span><span><span></span>></span>
</span></span></span></span></span></span></span></span></span></span></span></span>

This is a WordPress-idiomatic way of including scripts and styles in a theme. It allows us to specify that the position of the scripts will be enqueued (header vs footer) and the priority of enqueuing. We can even specify the dependency of each particular resource on the other. This will ensure resources will be loaded in the right order.

We’re using the wp_enqueue_scripts action hook here. We can learn more about it in the Codex. (We covered action hooks in the previous article.)

Inside our custom bsimple_scripts() function — which we hook to wp_enqueue_scripts action hook — we use two WordPress functions to load our scripts and styles — wp_enqueue_script() and wp_enqueue_style(). Arguments for these functions — as specified in its linked reference pages — allow us to fully leverage flexibility that we mentioned.

We can see that we’re loading styles from the Internet (Google fonts) and from our theme folder. Therefore, we create css, js and webfonts directories in our theme folder, and copy our Bootstrap theme’s CSS, JavaScript files, and FontAwesome icon-font files.

We also copy our index.php file to archive.php, page.php and single.php files, which we’ll modify.

Now our theme file structure will look something like this:

Adjusting the Markup

If we now visit our home page, we’ll see the menu on the top — though it and the page are still a mess – because the following line in our header is still outputting the menu wrapped in div and its own ul tags, so it isn’t affected by our bootstrap styles:

<span><span><?php </span></span><span><span>if ( have_posts() ) {
</span></span><span>    <span>while ( have_posts() ) {
</span></span><span>        <span>the_post();
</span></span><span>        <span>//
</span></span><span>        <span>// Post Content here
</span></span><span>        <span>//
</span></span><span>    <span>} // end while
</span></span><span><span>} // end if
</span></span><span><span>?></span>
</span></span>

To solve this, we first need to go to our wp-admin dashboard and create — in the customizer — a new menu. we’ll name it Top Menu.

After we’ve done this, we’ll go to our header.php file remove these lines:

<span>/*
</span><span>Theme Name: Botega Simple Theme
</span><span>Theme URI: https://botega.co.uk
</span><span>Author: Tonino Jankov
</span><span>Author URI: https://botega.co.uk
</span><span>Description: Basic WordPress theme for Sitepoint theme building tutorial
</span><span>Text Domain: bsimple
</span><span>Version: 1.0.0
</span><span>License: GNU General Public License v2 or later
</span><span>*/
</span>

In their place we put these lines:

<span><span><?php </span></span><span><span>/**
</span></span><span><span> *
</span></span><span><span> * <span>@package Botega_Scratch_Theme
</span></span></span><span><span> */
</span></span><span><span>?></span>
</span>
<span><span>
</span><span><span><span> <span><span><?php language_attributes(); ?></span></span>></span>
</span><span><span><span>></span>
</span>    <span><span><span><title>></title></span><span><?php bloginfo('name'); ?></span><span><span></span>></span>
</span>    <span><span><span><link> rel<span>="stylesheet"</span> href<span>="<span><?php bloginfo('stylesheet_url'); ?></span>"</span>></span>
</span>    <span><span><?php wp_head(); ?></span>
</span><span><span><span></span>></span>
</span><span><span><span>></span>
</span>
      <span><span><span><header>></header></span>
</span>         <span><span><span><h1 id="gt">></h1></span><span><?php bloginfo('name'); ?></span><span><span></span>></span>
</span>         <span><span><span><h3 id="gt">></h3></span><span><?php bloginfo('description'); ?></span><span><span></span>></span>
</span>      <span><span><span></span>></span>
</span>
        <span><span><?php </span></span><span>        <span>if ( have_posts() ) :
</span></span><span>            <span>/* Start the Loop */
</span></span><span>            <span>while ( have_posts() ) :
</span></span><span>                <span>the_post();
</span></span><span>            <span>endwhile;
</span></span><span>        <span>endif;
</span></span><span>        <span>?></span>
</span>
<span><span><span></span>></span>
</span></span></span></span></span></span></span></span></span></span></span></span>

This will remove the div tag and the duplication of the ul tag for us, but we still need to apply nav-item and nav-link to our menu items (to li and a tags respectively). How will we go about this? wp_nav_menu does not provide arguments for this. We’ll use the nav_menu_link_attributes and nav_menu_css_class filter hooks. We put this into our functions.php file:

<span><span><?php </span></span><span><span>if ( have_posts() ) {
</span></span><span>    <span>while ( have_posts() ) {
</span></span><span>        <span>the_post();
</span></span><span>        <span>//
</span></span><span>        <span>// Post Content here
</span></span><span>        <span>//
</span></span><span>    <span>} // end while
</span></span><span><span>} // end if
</span></span><span><span>?></span>
</span></span>

Now we can specify new attributes in our wp_nav_menu in our header.php:

    <span><span><?php </span></span><span>    <span>if ( have_posts() ) : while ( have_posts() ): the_post(); ?></span>
</span>
    <span><span><span><div> id<span>="post-<span><?php the_ID(); ?></span>"</span>>
        <span><span><span><h2 id="gt">></h2></span><span><?php the_title(); ?></span><span><span></span>></span>
</span>        <span><span><span><div> class<span>="post-excerpt"</span>><span><?php the_excerpt(); ?></span><span><span></span></span>
</div></span>></span>
</span>    <span><span><span></span></span></span></span>
</div></span>></span>
</span>
    <span><span><?php endwhile;
</span></span><span>    <span>endif;
</span></span><span>    <span>?></span>
</span></span></span>

Now our top menu links can take advantage of styles already defined in our Bootstrap theme’s CSS.

Dynamic Header

To be able to use a dynamic header — that is, a different header for the front page, for other selected pages, or for archives — we’ll define a dynamic_header() function in our functions.php file, where we’ll output our header markup dependent on the page the visitor loads.

So now our header.php file will end like this:

<span><span><?php </span></span><span><span>/**
</span></span><span><span> *
</span></span><span><span> * <span>@package Botega_Scratch_Theme
</span></span></span><span><span> */
</span></span><span>
</span><span><span>get_header(); ?></span>
</span>
    <span><span><?php </span></span><span>    <span>if ( have_posts() ) : while ( have_posts() ): the_post(); ?></span>
</span>
    <span><span><span><div> id<span>="post-<span><?php the_ID(); ?></span>"</span>>
        <span><span><span><h2 id="gt">></h2></span><span><?php the_title(); ?></span><span><span></span>></span>
</span>        <span><span><span><div> class<span>="post-excerpt"</span>><span><?php the_excerpt(); ?></span><span><span></span></span>
</div></span>></span>
</span>    <span><span><span></span></span></span></span>
</div></span>></span>
</span>
    <span><span><?php endwhile;
</span></span><span>    <span>endif;
</span></span><span>    <span>?></span>
</span>
<span><span><?php get_footer(); ?></span>
</span></span></span></span>

We’ll also define that function like this:

<span><span><?php </span></span><span><span>/**
</span></span><span><span> * The header for our theme.
</span></span><span><span> *
</span></span><span><span> * <span>@package Botega_Scratch_Theme
</span></span></span><span><span> *
</span></span><span><span> */
</span></span><span><span>?></span>
</span><span><span>
</span><span><span><span>></span>
</span><span><span><span>></span>
</span><span><span><span><meta> charset<span>="<span><?php bloginfo( 'charset' ); ?></span>"</span>></span>
</span><span><span><span><meta> name<span>="viewport"</span> content<span>="width=device-width, initial-scale=1"</span>></span>
</span>
<span><span><?php wp_head(); ?></span>
</span><span><span><span></span>></span>
</span>
<span><span><span> <span><span><?php body_class(); ?></span></span>></span>
</span>
  <span><span><span><nav> class<span>="navbar navbar-default navbar-custom navbar-fixed-top"</span>></nav></span>
</span>    <span><span><span><div> class<span>="container-fluid"</span>>
      <span><span><span><div> class<span>="navbar-header page-scroll"</span>>
              <span><span><span><a> href<span>="<span><?php echo esc_url( home_url( '/' ) ); ?></span>"</span> rel<span>="home"</span> class<span>="navbar-brand"</span>></a></span><span><?php bloginfo( 'name' ); ?></span><span><span></span>></span>
</span>      <span><span><span></span></span></span></span>
</div></span>></span>
</span>
      <span><span><span><div> class<span>="collapse navbar-collapse"</span> id<span>="bs-example-navbar-collapse-1"</span>>
          <span><span><span><ul> class<span>="nav navbar-nav navbar-right"</span>></ul></span>
</span>          <span><span><?php wp_nav_menu( array( 'theme_location' => 'primary', 'items_wrap' => '%3$s' ) ); ?></span>
</span>          <span><span><span></span>></span>
</span>      <span><span><span></span></span></span></span>
</div></span>></span>
</span>    <span><span><span></span></span></span>
</div></span>></span>
</span>  <span><span><span></span>></span>
</span>
  <span><span><span><div> class<span>="container"</span>>
      <span><span><span><div> class<span>="row"</span>>

<p>To be able to use all the current URL or post data — like in the loop — we declare a $post variable global. Then we just fill different page or request cases with filler header HTML, which we’ll finish later. This sets the foundation for a truly dynamic header.</p>
<p>We need to make sure that our front page — with dynamic top menu — will look good even when the user is logged in. WordPress shows an <em>admin bar</em> when visitors are logged in, even when they visit the front page. Because it has position: fixed, it overlays the top zone on our website, covering whatever is there, so we need to specify an offset for our top menu.</p>
<p>We’ll add this to our style.css:</p>
<pre class="brush:php;toolbar:false"><span><span><?php </span></span><span><span>/**
</span></span><span><span> * Footer template partial
</span></span><span><span> *
</span></span><span><span> * <span>@package Botega_Scratch_Theme
</span></span></span><span><span> *
</span></span><span><span> */
</span></span><span><span>?></span>
</span>     <span><span><span></span></span></span></span>