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In this hands-on course, James Williamson demonstrates the concepts that form the foundation of Cascading Style Sheets (CSS), including styling text, adding margins and padding, and controlling how images display. The course also explores the tools needed to work with CSS, the differences between embedded and external styles, how to use selectors to target elements, and what to do when styles conflict.
In addition to dynamic pseudo- class selectors, you have structural pseudo-class selectors that allow you to target elements based on more complex patterns within the DOM. Now what this means is that you can target elements based on conditions like whether or not they are the first child of an element, whether they are the only child of it, and other factors. So let's take a closer look at some of those selectors. And before we get into the code of this, I just want to show you the page that we are going to be targeting. So I am going to switch over to my browser, and here I can see that it's a little bit more complex of a page than what we've been using.
It looks a lot like one we were using in one of the previous exercises, however, where we were targeting the first paragraph after heading, for example, and we're going to sort of extend what we're doing there. So we still have those styling needs. We are going to be styling some of those headlines, some of the main text that comes directly after them. And one of the things I really want to do is I want to indicate the beginning of each section by using this line. But not all of the subheadings are the beginning of a section, so I need some way of sort of filtering those out. And that's one of the things I really like about the structural pseudo-class selectors: they allow me to do this really complex targeting without using any class attributes, so I am a big fan of that.
All right, I am going to jump back into my code, and just again to sort of reinforce what we were talking about, we have an article and inside that article we have multiple sections. The first section is followed immediately by an h1, but every other section after that has an h2 that begins the section. Now, one of the sections has multiple h2s in it. So if we go to this one, for example, we have a beginning h2, and then we have another h2 that's still inside the section, but it's not the first heading of the section. And then at the very bottom of this, we have a paragraph that happens to be the only element of the section.
Okay, so now that we know kind of how the page is structured and kind of some of the things what we want to target, let's go back up and see how structural pseudo-class selectors can help us do that. Okay, so the first thing I want to do is target these spans. You'll notice that each of the initial paragraphs in a section have part of their first paragraph wrapped in a span tag, and this is going to allow me to sort of do some really customized styling to the first paragraph of every section. So I am going to right up to where it says add styles here, and inside that I am going to type in span and then a colon, because remember every pseudo-class selector uses that colon as part of the syntax with no space, and then I am just going to type in first-child.
So I am going to open up my brackets. And essentially what first-child is is it's saying hey, find every span in the document and if it's the first child of its parent element, go ahead and give it this styling. So it won't apply to every single span, just when that span happens to be the first child of its parent element. So what I am going to do here is I am going to say font-size 1.3ems, font-weight, and that's going to be bold, and color is going to be maroon.
Okay, so I am going to go ahead and save that. I am going to go back into my browser, refresh the page, and you can see that all of those initial paragraphs, the text that I have surrounded with the span tag because it's the first child of its parent paragraph, goes ahead and gets that styling. Cool! Now back in my code, I want to address the problem that I was having with those subheadings. I only want the subheadings to have a border underneath it if they're the first subheading in a section--and I don't want every subheading, just the first one-- because that indicates sort of the beginning of the section.
So what I am going to do is I am going to go ahead and write the selector for this just below the span. I am going to type in h2:first-of- type and open up my curly braces. So what this is doing is it's saying, hey, go ahead and take a look at h2s. I'll find all the h2s, and then look and see when they are inside of another element, inside of a parent element. When they are the first h2 within that parent element, style them. So it'll ignore every single one after it.
It's just first of type. So I am going to scroll up a little bit into my existing styles, and I can see that all the h2s have this border-bottom property applied to it. I am going to cut that property out--so I am just using Command+X or Ctrl+X to do that--and then if I scroll back down to that selector, I can just paste that styling right in the selector. I don't have to write that over again. So I am going to save that, and now if I preview this and refresh my page, I can see as I scroll down, the first subheading in this section is getting the border, but the second subheading is not.
That's allowing me to target that very complex pattern without using class attributes or class selectors, so that's really nice. Now I should point out that typically if you see a first-child, there is also a last-child option. If you see a first-of-type, there is also a last-of-type option. You know you can match those also if they are the last element within a parent element as well. Now let's go down and do one more structural pseudo-class selector. I just want the h2. I am going to do p:only-child, and I am going to go ahead and just do some really basic styling here.
I am just going to do font-style: italic; text-align: center. I am going to save that and now if I go back into my browser and refresh this page, when I scroll down, I can see right here where this paragraph says, "I am the only element within this section," it goes ahead and gets that styling. Now there are some variations on this as well. This p:only-child is basically saying that hey, whenever you find a paragraph and that paragraph is the only child inside of a parent, go ahead and give it that styling.
There is also only of type, so you could basically say that hey, when I'm the only paragraph inside of a parent element style me like this. But in terms of only-child, you're targeting it only when it's the only child within that. So the thing I like about these is that you can use these structural pseudo-class selectors to achieve far more complex targeting than we could ever do with simple selectors. Like I said earlier, in many cases it's going to save you from having to resort to using non- semantic classes to mainly go in and target those elements where you just want to add some visual styling.
Now I do feel like I should point out here that not all pseudo-class selectors are supported evenly across browsers, and especially browser versions, so older ones don't have as widespread support for some of these really specific ones. So be sure to go ahead and check for browser compatibility before you begin using them. Now there are also a few other structural pseudo-class selectors that I didn't cover here. One of them specifically is called nth- child, and we're going to talk about that in its own movie, because there's so much that you can do with nth-child. But be sure to read through the Selectors Level 3 Specification and explore all of the structural pseudo-class selectors that you have available to you.
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