How to Customize a WordPress Theme With CSS

When we decide to customize a WordPress Theme with CSS without a solid knowledge, because it seems so easy! (it can be), we usually begin copying and pasting snippets in the WP customizer and end up with a thousand lines of a huge mess.

“Been there. Done that”. It is actually how I started coding. Then, as years went by, I began thinking, “I wish I had known that! This was so easy!” Hence: this guide for you 😉.

Customizing a Theme With CSS Can Be Easy, “If”

Customizing a WP theme with CSS can be very simple for two reasons:

  1. CSS is a language very easy to learn.
  2. A tool to do so, the “WordPress Customizer” is at the palm of our hands.

However, writing in CSS can be simply only if you have at least some idea of the basic concepts.

For instance, if you don’t know what the “box model” is, you’ll be jumping into “something” blindfolded. It can be a pond, a deep pool or a cliff. You don’t know.

And then, regarding working with the WP customizer: How many snippets have you pasted there? Do you have a clear idea of what you’ve done? Do you understand why that snippet that works for everyone doesn’t work for you?

What Are the Steps to Customize a WP Theme With CSS

My goal with this guide is to give you a learning path to follow.

Quick and easy, I’ll be covering the basic concepts you are to know, so that you’ll comprehend what you’ll be doing when you copy and paste a snippet you’ve found.

I will also show you how you can come up with your own snippets! But in order to do that, we need to … “follow a path.”

Overall, this is how it goes

Step 1: Learn the Languages

Before even thinking about customizing a theme with CSS, you are to know exactly what you are doing. A good place to start is to discover the following:

  • Regarding HTML: the structure of a website; the difference between a class and an ID; the parent-children relationship between the elements.
  • Regarding CSS: the Box Model; what we can and cannot do (such as adding links); the difference between selectors and pseudo-selectors; how to keep our theme responsive

And even if you are not going to create a Child Theme, having a notion of PHP and the WordPress Functions, is extremely helpful.

If you download the theme to your machine and read its files, you’ll understand how the theme is built (like a puzzle!) and you’ll come across many of the selectors you need.

Bottom line is: you are to understand what you’re looking at when you have a theme displayed on your screen. What is the header, the main area, the footer, etc.

Step 2: Master WordPress, its Interface and the Use of Blocks

Every theme comes with different features (such as templates, patterns, post-types) and the blocks we use in the WordPress editor also come with different options to customize them.

For instance: in the Twenty Twenty One theme, we can select the padding of the “Group Block” from the WordPress editor; which, we cannot do in the Twenty Twenty theme.

If you haven’t practice enough (with any theme) and you don’t know exactly what your needs and preferences are, customizing or even choosing a theme is going to be a long task.

Step 3: Listen to the Author of the Theme and Test

Each theme was developed by one or more authors that have dedicated their time to leave us good insights about their work (such as the “Details” of the theme, a demo website, a support forum.)

Even though, as we’ll see, that basic information won’t be enough to know everything we need to customize a theme, it must be our starting point.

For instance: the Twenty Twenty theme comes with an “Expanded Menu”, which is a great feature for those who have a lot of links in their primary menu and would like to keep this one cleaner. But, it is not mentioned in the Details nor displayed in the Demo.

Humble advice? Read the details, check out the demo, take notes. And then, give it a try from the WordPress dashboard.

Step 4: Grab the Tools

The WordPress customizer seems to be enough to flip our theme with CSS, but it is not the most efficient way to do so.

There are basic tools to code which you shouldn’t be afraid of using. Tools that are free, and very intuitive and easy to use. In this guide, we’ll be working with:

  • Sublime Text
  • The Developer Tools
  • MAMP / WAMP (if you’re looking forward to test your theme on your machine, or to create a child theme)

To customize a theme, it is imperative that you study it first.

In this guide, I am going to walk you through that process, leaving for you links to great tutorials that you won’t believe that were floating on the web, for free.

Laly York. Neurodivergent Gen-X writer / B.Ed. / Lawyer. Writing, coding and taking pics. From Jupiter, living in a soap opera; flying on the web with three blogs.


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