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    Chain Simple CSS Selectors for Fine-grain DOM Element Targeting

    Garth BraithwaiteGarth Braithwaite

    To be more specific when targeting DOM elements, we can combine selectors or chain them to style children or multiple groups.

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    Instructor: 00:00 CSS rule sets can add multiple selectors to reduce code repetition. You can also combine selectors to be more specific with which elements to target. We're going to look at some simple selector combinations in a fairly common example, a website navigation.

    00:16 Looking at the markup, you can see we have a bunch of list items or nav items here that have links. This one doesn't have a link, but it has a selected class. This one's actually a button. Let's go ahead and start to style this up.

    00:30 Here, I've got some already predefined stuff, but let's start with the site nav. We're going to go ahead and set the padding to 0and 20 pixels, because we're going to move it away from the edge a little bit.

    00:41 We'll actually remove some of the styling of the list itself. We'll turn the list style to none, and we'll set the padding on this to zero. We'll also change the font size to be something just a little bit smaller, because we're actually going to change the text transform to be uppercase.

    01:03 We will also space out the letters a little bit. We're going to uncomment out this, which is going to change the background color to this gradient, and we'll also change the font family to a san serif.

    01:20 Now, let's go ahead and style up the list items. We're going to set their display to inline block to make them go on a straight line. In both of these last ones, the site nav UL and the site nav LI, these are combined selectors.

    01:35 We could have just targeted the unordered list and the list items, but because we have prefaced it with the .site nav with the space, that's going to be much more specific.

    01:45 If we ever use another unordered list or a list item, which is very likely in this website, we don't have to worry about accidentally styling those items as well. This is very specific to just these list items and unordered list inside the site nav.

    02:01 The space is a descendant selector. If I'm using just the space, that means that this is going to target any UL that is a descendant of the site nav class. If we look at the HTML, the site nav is here, and then you've got a URL right underneath it. Then you've got list items right inside of that.

    02:20 If we look, this .site nav space LI, this is going to be any list item that falls within the .site nav, even if it's not a direct descendant. To use direct descendant, we actually use the greater than symbol. That would work here for the unordered list, but if I went ahead and added it to the list items, that would stop targeting them, because these list items are not directly underneath the .site nav.

    02:48 We could add it to the unordered list, but that is a little too specific for what we need, because to be honest, it's not likely we're going to have nested unordered lists in this nav. If we did and we needed to target those specifically, we could use that.

    03:01 Let's go ahead and keep styling. Let's change these nav items. We'll space them out a little bit here, set the margin right to 30 pixels. Let's go ahead and style the links. They've got the blue color in that underline. To be able to change that, I have to target them specifically.

    03:21 We also have this selected nav item that doesn't have a link inside of it or an a tag inside of it. Let's add that selector. Let's change the color to white. I actually have a typo here. The nav item shouldn't -selected. It should be .selected.

    03:39 We don't actually have the space here between these two classes. That's because this is no longer a descendant selector. We're actually targeting the same element. If we look at the HTML, our selected item has nav item and selected as classes that are applied to this list item.

    03:56 To target that with the CSS, we can actually combine the two selectors without a space. That means that this is one element that has two classes on it. Let's go ahead and get rid of that text decoration, that underline.

    04:10 We'll set that to none so the underline will go away on the links and also on the selected item. Not that it has it, but if it did, it would go away.

    04:18 Then let's change the padding on the bottom. We're going to do this because we're actually going to add and underline using a border, which gives us a little bit of control on hover state. To add that, let's go ahead and add a selector for the a hover.

    04:33 We also want this to be the styles for the actual selected item. It'll have this underline if the item's the current selected item, like we're on that page, or if they hover over it. Border bottom, we'll set that to one pixel, solid, and it'll pick up the white from the font color. If I hover over these, you can see the underlines there, and the contact has the underline. We're good.

    05:00 Let's go ahead and style this login button. We'll use the descendant selector here. Button is actually inside of the .login button class. We're going to set the background to transparent. We'll set the color to white as well.

    05:16 Let's set the border to one pixel, solid. We'll set the padding just to space out things a little bit inside that button. Let's style the typography to actually match the rest of the items. We'll do the font size, the text transform to be uppercase. Let's do the letter spacing as well.

    05:51 Those have sharp corners. Let's adjust the border radius. We want it to look like it's clickable. Let's change the cursor to pointer. Let's also change the hover state on this. We'll go ahead and change the background to be white. We'll just flip the colors. We'll change the color.

    06:17 We can't make it transparent, but we will try and match the closest color to the location, which is that greenish color, teal. We've got to also set the border color, because it's going to be different than the font color.

    06:33 I'm looking here in this typography styling that we did. We actually did up above, and there's no reason to repeat ourselves. Let's go ahead and take that out, and let's figure out where we have this up above. Looks like it's in the unordered list.

    06:46 There are some styles here that don't apply to this item. That's fine, because we'll ignore those. Let's copy this selector or use the comma. What the comma does is it actually makes it so that I can apply the same rule set to two different selectors.

    07:03 We used it down below, and it's a way to avoid having to repeat code. Any time I want to change the font size now for these items, it's only in one place. If I change it here, it'll apply to all the UL, but also to the button, which has different styling.

    07:20 I also don't have to worry about the padding zero here, because I actually set it to the correct padding down below, which will override the styling. Everything looks good.

    07:29 We've looked at how we can combine selectors to be more specific, or we can actually add multiple selectors to save on repeating ourselves and making the code just a little bit easier to maintain.

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