Creating a CSS3 box-shadow on all sides but one

问题:

I've got a tabbed navigation bar where I'd like the open tab to have a shadow to set it apart from the other tabs. I'd also like the whole tab section to have a single shadow (see bottom horizontal line) going up, shading the bottom of all tabs except for the open one.

I'm going to use CSS3's box-shadow property to do it, but I can't figure out a way to shade only the parts I want.

Normally I'd cover up the bottom shadow of the open tab with the content area (higher z-index), but in this case the content area itself has a shadow so that would just wind up covering the tab.

Tab layout

      _______    _______    _______     |       |  |       |  |       | ____|_______|__|       |__|_______|______  

Shadow line.

Shadow would go up from the horizontal lines, and outward of the vertical lines.

                 _______                |       | _______________|       |_________________  

Here is a live example:

Any help out there, geniuses?

回答1:

In your sample create a div inside #content with this style

#content_over_shadow {     padding: 1em;     position: relative; /* look at this */     background:#fff;    /* a solid background (non transparent) */ } 

and change #content style (remove paddings) and add shadow

#content {     font-size: 1.8em;     box-shadow: 0 0 8px 2px #888; /* line shadow */ } 

add shadows to tabs:

#nav li a {     margin-left: 20px;     padding: .7em .5em .5em .5em;     font-size: 1.3em;     color: #FFF;     display: inline-block;     text-transform: uppercase;     position: relative;     box-shadow: 0 0 8px 2px #888; /* the shadow */ } 

回答2:

Cut it off with overflow.

tab
 

回答3:

You can use multiple CSS shadows without any other divs to get desired effect, with the caveat of of no shadows around the corners.

-webkit-box-shadow: 0 -3px 3px -3px black, 3px 0px 3px -3px black, -3px 0px 3px -3px black; -moz-box-shadow:    0 -3px 3px -3px black, 3px 0px 3px -3px black, -3px 0px 3px -3px black; box-shadow:         0 -3px 3px -3px black, 3px 0px 3px -3px black, -3px 0px 3px -3px black; 

Overall though its very unintrusive.

回答4:

Personally I like the solution found here best: http://css3pie.com/demos/tabs/

It allows you to have a zero state or a hover state with a background color that still has the shadow from the content below overlaying it. Not sure that's possible with the method above:

UPDATE:

Actually I was incorrect. You can make the accepted solution support the hover state shown above. Do this:

Instead of having the positive relative on the a, put it on the a.active class with a z-index that is higher than your #content div below (which has the shadow on it) but is lower than the z-index on your content_wrapper.

For example:

My company name
     
Benefits
         
Features
         
Contact
         
Company
     
     
         content goes here     
 
 

then with your css:

#ppPage-Body     box-shadow: 0 0 12px rgba(0,0,0,.75)     position: relative /* IMPORTANT PART */  #ppPage-BodyWrap     background: #F4F4F4     position: relative /* IMPORTANT PART */     z-index: 4 /* IMPORTANT PART */   .ppList_PrimaryNavigation li a:hover     background: #656565     -webkit-border-radius: 6px 6px 0 0     -moz-border-radius: 6px 6px 0 0     border-radius: 6px 6px 0 0  .ppList_PrimaryNavigation li a.ppStyle_Active     background: #f4f4f4     color: #222     -webkit-border-radius: 6px 6px 0 0     -moz-border-radius: 6px 6px 0 0     border-radius: 6px 6px 0 0     -webkit-box-shadow: 0 0 12px rgba(0,0,0,0.75)     -moz-box-shadow: 0 0 12px rgba(0,0,0,0.75)     box-shadow: 0 0 12px rgba(0,0,0,0.75)     position: relative /* IMPORTANT PART */     z-index: 3 /* IMPORTANT PART */ 

回答5:

One more, rather creative, way of solving this problem is adding :after or :before pseudo element to one of the elements. In my case it looks like this:

#magik_megamenu>li:hover>a:after {     height: 5px;     width: 100%;     background: white;     content: '';     position: absolute;     bottom: -3px;     left: 0; } 

See the screenshot, made the pseudo element red to make it more visible.

回答6:

If you added two spans to hook onto then you could use two, something like:

box-shadow: -1px -1px 1px #000; 

on one span and

box-shadow: 1px -1px 1px #000; 

on another. Might work!

If the shadows overlap you could even use 3 shadows - one 1px to the left, one 1px to the right and one 1px up, or however thick you want them.

回答7:

you can cover up shadow using multiple box shadows as well.

box-shadow: 0 10px 0 #fff, 0 0 10px #ccc;

回答8:

If you are willing to use experimental technology with only partial support, you could use the clip-path property.

This will produce the desired effect: a box shadow on the top, left and right sides with a clean cut-off on the bottom edge.

In your case you would use clip-path: inset(px px px px); where the pixel values are calculated from the edge in question (see below).

#container {     box-shadow: 0 0 8px 2px #888;     clip-path: inset(-8px -8px 0px -8px); } 

This will clip the div in question at:

• 8 pixels above the top (to include the shadow)
• 8 pixels outside of the right edge (to include the shadow)
• 0 pixels from the bottom (to hide the shadow)
• 8 pixels outside of the left edge (to include the shadow)

Note that no commas are required between pixel values.

The size of the div can be flexible.

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