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Basic Box Shadows

Basic Box Shadows

5:52

This video will teach you how the box-shadow property in CSS3 allows you to put drop shadows around your elements. A drop shadow effect on a dynamically sized element can be tricky to pull off, but box-shadow can do it with just a single line of code.

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    [?upbeat music?]

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    [Think Vitamin Membership] [??]

  • 0:07

    [CSS3 Borders - Basic Box Shadows - with Nick Pettit] [??]

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    Box shadow is a new CSS3 property that allows you to put drop shadows

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    behind your page elements.

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    If you've ever tried to create this effect before without the use of box shadow,

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    you know just how unnecessarily difficult it can be.

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    Box shadow aims to make it a whole lot easier.

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    Let's check it out.

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    Here you can see I've created a basic page for us to work with.

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    There is a div in the center of the page

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    that we'll be applying our box shadow to.

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    Switching over to my text editor, you can see that the markup is also pretty standard stuff.

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    There's a wrapper div, and there's the div right in the center of the page.

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    I've also applied some basic styling just to bootstrap the page

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    and make it a little bit prettier for us to look at.

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    We are going to be working in a separate style sheet just for the sake of clarity.

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    First I'm going to select my div,

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    and then I'm just going to apply a basic box shadow,

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    and then after it's been applied I'll step through it one piece at a time with you.

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    So we'll type WebKit box shadow,

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    and I'll set the X offset, Y offset,

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    and we'll apply color.

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    And we'll switch back to Google Chrome,

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    and you can see that a very rough shadow has been applied.

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    We can also do this in Firefox just by using the same syntax

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    and switching the browser prefix from WebKit to Mozilla.

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    You can see that this works in Firefox as well.

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    Pretty cool.

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    The first thing you probably notice are the browser prefixes, WebKit and Moz.

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    That's just there so that should the W3C decide to change the box shadow property

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    in the final specification, that we don't have compatibility problems down the road.

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    The first two parts of box shadow are the X offset and the Y offset.

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    In this case I've set them both to 10 pixels,

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    but you can also use ems as your unit of measurement.

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    However, you cannot use percentages.

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    Each one of these values measures from the upper left-hand corner of the element,

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    and the higher the number, the greater the offset will be.

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    You can also apply negative values to each one of these,

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    and I'll show you what that looks like in Google Chrome.

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    Just by applying a negative value, you can see that the shadow

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    has been flipped over to the upper left-hand side.

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    Now, what we've done so far is pretty interesting,

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    but it doesn't look very realistic.

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    We can add some realism by adjusting the blur radius and the opacity.

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    The first value is always the X offset.

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    The second value is always the Y offset.

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    But the third value is optional, and if you leave it blank,

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    there will be no blur radius.

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    However, if we were to add a value like 10 pixels here, for example,

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    we could switch back to our browser and see that the shadow has been blurred slightly.

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    Of course the higher the value for the blur radius,

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    the fuzzier the shadow will end up looking.

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    This also works in Firefox.

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    [clicking]

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    Next up is the color of the shadow.

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    In this case I've set it to a hexadecimal value,

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    and I've set the color to black,

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    but this can actually be any color that you want.

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    We could use a solid color like normal,

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    but CSS3 introduces several new color models.

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    The RGBa color model allows for more subtle effects,

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    so let's give that a try.

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    RGBa is a function just like the URL function,

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    so you type RGBa and then you put parentheses right after that.

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    The RGBa function accepts four values.

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    There's the red value, the green value, the blue value, and finally, an alpha value.

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    The first three values are numbered between 0 and 255.

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    In this case I've set them all to be 0.

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    But the alpha value is a bit different.

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    Alpha has to be a number between 0 and 1.

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    We probably don't want our shadow to be 100% opaque,

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    so we'll take the alpha value down a little bit from 1 and we'll try 0.8.

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    Switching over to Google Chrome, you can see that the shadow

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    has lightened up a little bit, and when it's against patterned backgrounds

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    or other solid colors, this allows the shadow to blend in with the background,

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    and it makes it look a lot more realistic.

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    Just to show you some of the other things that you can do with the RGBa function,

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    we'll add in a little bit of blue,

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    and we'll dial down the opacity a little bit more.

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    Switching back to Google Chrome, you can see that our shadow

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    now has a slightly blue hue to it.

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    Of course this also works in Firefox,

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    so I'll just go ahead and copy and paste here

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    and change the browser prefix to Mozilla.

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    Switching over to Firefox, you can see that our shadow is also slightly blue in Firefox.

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    Pretty cool.

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    [?upbeat music?] [Think Vitamin Membership]

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    [??]

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