I have updated the final code to function properly with the Firefox14 update from July 2012. Firefox stopped using transform skew, and moved to transform matrix code. -Alex

Who doesn’t love Post-it notes? In my previous life, before I started learning CSS, I would ask myself “how can I make a convincing looking Post-it note in Photoshop?” After extensive CSS study and research I have come to realize that some things can be done with CSS alone. That’s right, the post it you see on the right is 100% CSS. Go ahead, check it out. Here is how it is done.

I broke the instructions up into key elements so the uninitiated can get a feel for how I constructed everything. The process itself might be helpful for some people – it was certainly helpful for me. If you aren’t interested in my life story, feel free to skip to the end for a quick ‘plug and play’ code snippet.

Making the Post-it

This is the basic square that will be built around your content. The height is somewhat complicated because I want the text to begin lower on the Post-it rather than at the top. To ensure the padding doesn’t add any height while still lowering the text, set a min and max parameter on the height.

The Yellow Hex Color

This is where much of the magic happens. When you think of a Post-it note you probably think of the yellow hex color, right? It’s true, but we need to think in 3D terms. It needs a yellow gradient that fades at a 45-degree angle into a slightly lighter color at the bottom right. This will help with creating a “peeled up” illusion later on. I just used this amazing tool (http://www.colorzilla.com/gradient-editor) to make mine. This code looks like a huge mess, but it’s mostly due to cross-browser support. Speaking of cross-browser support, Internet Explorer 6-9 does not like diagonal gradients so this website provides a nice fallback and converts our diagonal gradient into a horizontal gradient. This is not optimal so I recommend changing the last line of code here:

Either make startColorstr and endColorstr the same number (which will turn off the gradient and make the Post-it a solid color) or change GradientType from 1 to 0 (this will make the gradient vertical instead of horizontal). I chose to remove the gradient.

I am doing something special with the border. You could easily give this a 1px light grey border and it would look fine, however, Post-its have that sticky glue-like substance on top that, when in use, has a slightly different look than the rest of the Post-it. I created a thick top border that is nearly the same color as the yellow I used. The effect is so slight you almost can’t tell it’s there, but anyone who does will surely appreciate it.

Font Styling

This is my font styling. Consider putting a script font on your post it, something like Marker Felt or Comic Sans, or preferably something interesting from the Google Font API like Reenie Beanie seen here.

A Peeled Corner

Although Post-its are square, the bottom corners tend to peel off the surface a bit when stuck to something. This 3D effect is subtle, but adds a ton to the feel of the note. This is the code to make only the bottom right corner look peeled for most browsers. As usual, sorry IE users.

And there we have it. The final code for the Post-it class looks like this:

I know what you are thinking. Where is the shadow? Well, the shadow is actually a different piece of CSS. We’re doing more than simply adding a box shadow around the note. We could do that, but then it would look like the Post-it is floating rather than stuck on the wall.

Creating a non-box shadow is a bit of a workaround. We are actually going to be making a shape, giving that shape a shadow, and carefully adjusting that shape/shadow so only about 5% of it is visible. Sounds easy, right? I used this website to fine tune my effect (http://www.wordpressthemeshock.com/css-drop-shadow). It took me some playing to get it right, but I am happy with the result.

The Bottom Corner Shadow

Here is our shape. It’s a long rectangle that has been skewed to have more acute angles.

This positioning hides the box behind our Post-it and makes sure it stays underneath. I ran into an interesting problem when using this on a template sites like the one you are on now. The negative z-index actually put the shadow behind the background, making it invisible. I am not sure if this will be the case on other CMS sites, or other templates, but to get around this problem you simply need to give your background a z-index of 0.

Finally, the shadow. It takes a bit of tweaking to make it show up just right. Also you might have noticed that box-shadow is commented out. This is the IE workaround. IE doesn’t support rotation or skew so the shape that is actually making our shadow doesn’t cast the correct shadow. Without a box-shadow, it is just hidden under the yellow not not bothering anyone. The shadow website I provided above wants you to put together your inline code in a funny way. After you wrap your content in the .postit class, you need to make another empty div just to hold the box shadow. Like this:

That is a bit clunky and I always want to do less inline work, so I put my own spin on things. Instead of making a separate class for the cornershadow, which would look like this:

The above code is now obsolete as browsers have moved to using matrix over skew. Here is functionally equivalent code, also updated in the final code. -Alex

…I used the pseudo class :after to simply put the cornershadow code after all postit class divs! So now all you need to do is make a div class=”postit” and put whatever you want in it!

The complete code: (Updated July 2012)

And the inline code:

If you want to further increase your Post-it fun consider separating the colored gradient and borders into its own class, naming that class .yellow. Then create a class for other Post-it colors like .blue, .pink, .orange, and so on. That way you get to name your div class=”postit pink” and get different colors. You can also give your Post-its a rotation (like the one I have at the beginning of this post) by wrapping it in a div and giving that div rotate transformation.