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CSS Flags

Recreating all the flags of the nations of the world in pure CSS, using only one div per flag.

You can see it live on https://pixelastic.github.io/css-flags/

This side-project has no real-world application, it was just an exercise to push the boundaries of what I know about CSS. Trying to use the language to do things it wasn't meant to do in the first place taught me a lot about the language.

Running the project locally

bundle install
npm install
npm run serve

The website will then be available on http://localhost:4001/.

Contributing

If you've spotted an issue with the rendering of a specific flag or if you know how to do one of the missing flags, I'm open to pull requests.

Compatibility

I've only tested the rendering on Chrome and Safari so far. I plan on making it cross-browser but I need to add visual non-regression testing first.

Sources

To create the flags, my three most important sources were the Wikipedia, CRWFlags and Vexilla Mundi. CRWFlags contains valuable information about every flag history, allowing me to better understand how they were constructed. Vexilla Mundi contains handy construction sheet images with dimensions and angles.

I also used this list to get the list of all countries with their three letter ISO code.). This website also gives a nice overview.

Not all flags have an exact definition of the colors to use. Best case scenario, we have the official RGB/Hexa (or even Pantone) name of the color. Worst case, we have nothing and have to use the color used on the Wikipedia or Vexilla Mundi, even if it is not the official one.

Icons

To be able to display some of the very specific symbols used on some flags, I had to craft my own icon font, using icomoon.io.

I had to find svg versions of all the symbols used. Sometimes the symbols already exists in the UTF8 table, so I just have to grab them from existing fonts (or use utf8icons.com).

But more often, I had to use Vexilla Mundi. The website provides nice png images of all the symbols. Unfortunately, the symbols they provide are already colored, and I needed them black to use in the font so I was able to define the color myself.

The following script will do exactly that:

convert input.png \
        -alpha off \
        -fill black \
        -colorize 100 \
        -alpha on \
        output.png

I then had to trim the image to remove any whitespace left around the symbol:

convert input.png -trim output.png

Then, I need to convert the png to an svg. I couldn't find any commandline tool giving satisfying results, so I had to use an online service to do it: online-convert.com

Once I got the svg, it is just a matter of uploading it to icomoon, center the symbol, scale it and adjust the border. I also used the reserved namespace in the UTF8 table for custom characters. And finally exported the font.

FAQS

You're using half pixels. That does not make any sense.

Ok, that's not really a question, but I'll explain anyway.

I try to use percentage as much as I can, when it makes sense. Percentage are relative to either the width or the height of the flag. When doing a tricolore flag, I will use 33.33% as the width of each stripe for example. But as soon as I need to draw a square that has the same width than height, I can no longer user percentage values, I need real, absolute, pixel values.

Related projects

img2css

http://github.com/pixelastic/img2css/

Commandline tool to convert any image (jpg or png) to full CSS. This will replicate all pixels of the initial image using numerous box-shadows.

This works wel but results in really heavy generated CSS (several MB), so I choose not to use it in this project.

pantone2hex

http://github.com/pixelastic/pantone2hex/

Commandline tool to get an approximation in hexadecimal of a Pantone color value. Really useful as Vexilla Mundi gives color values in Pantone.

Vexillum

https://github.com/talgautb/vexillum

Someone else had the same idea.

Tips and tricks

Here is an incomplete list of the tricks I had to use:

Invisible text-shadow

I sometimes put an invisible symbol in an after or before element (through color: transparent) and positioned it at top:0; left: 0.

Then I added several text-shadow to it, with a full color. Doing so helped in getting the coordinates right because everything is then relative to the origin 0,0.

first-letter / first-line

When I needed to add more than 1 symbol in an after/before, or if I needed the same symbol, but on different sizes, I had to be sneaky.

By setting a content of "XY\AZ" and then using both first-letter and first-line, I was able to independently target X, Y and Z. \A is the special character to add a new line in a content.

Doing so let me use three different symbols, with different color and sizes with only one pseudo-element.

It is impossible to apply any transform (like a rotation) on those elements, though.

TODO

This project is not over, there are still some elements that I would like to add:

  • Link to codepen to let users play with the code
  • Making it work on more browsers...
  • ...which implies that I need to add a visual testing framework on top if it
  • Adding the missing flags
  • Using a clip-path when only one star instead of a font
  • Building the font with npm instead of icomoon.io
  • Adding stars to Brazil
  • Doing the Nepal flag
  • Check if Lea Verou has a background pattern close to the British India
  • Add the Leather Pride flag as an easter egg