duncanlock.net

cssmin is unmaintained & has a bug with complex :is selectors


Sometimes I want to have a just a tiny bit of CSS that’s unique, just for one page or post. I don’t want a whole stylesheet, or to have to add this to my site-wide theme, just for one post – I want a simple way to add it in the post itself.

This is how I did it:

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You can use the new CSS :is selector to write complex CSS selectors in a much more compact way


The content-type guessing done by AWS CLI is based on the mimetype definitions available on your system. You can improve the mimetype guessing by updating these definitions.


I had an issue where the AWS CLI wasn't guessing the content-type of SVG files correctly on sync and was setting them to `application/octet-stream` - the default "I don't know" mimetype. This is a quick fix for that.


Blueprint style diagram showing a Teapot.
Figure 1. A teapot, cut in half. Sort of. Original clipart Kitchen Utensils Silhouette, by GDJ, Public Domain. More on Teapots.

I’ve had a mysterious broken page on this site for a while - but been too busy to look into it. My Comprehensive Linux Backups with etckeeper & backupninja article has been refusing to load, and returning a weird HTTP 418 Unused status code instead. I finally made the time to figure out the cause.

It turned out that this was being caused by the Apache/PHP mod_security module. This is a static website - there’s no PHP anywhere - so why would that be a problem? Well, so far I’ve been very happily hosting the site on my old DreamHost shared hosting account - which comes with Apache & PHP installed whether you want it or not. At some point I …

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This site has been generated using Pelican 3.3 for over two years - and I finally found some time to upgrade to the current version of Pelican, 3.6.3. This is how I did the upgrade.

I decided to be lazy and do the upgrade in-place, instead of creating a new virtualenv and copying the content & settings over. Luckily, this worked out OK, after a bit of fiddling around.

I also decided, rather cavalierly, to upgrade all the packages in the virtualenv to their latest versions while I was at it. To do this, I upgraded pip, then used pip-review. To upgrade pip & install pip-review system wide, run this on the command line:

$ sudo -H pip install --upgrade pip
$ sudo -H pip install pip-review

Then upgrade eveything in the sites virtualenv:

$ sudo apt-get install libjpeg-dev
$ workon duncanlock.net
$ pip-review …
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There are quite a few changes in Pelican 3.3 - most of them minor, but a few which might mean making some changes to your site in order to upgrade. This is what I did to move my site from Pelican 3.2 to 3.3.

The change that had the biggest impact and took the most work was around image linking - caused by a combination of things. I think I was doing it wrong before and things changed in a way that meant this no longer worked. I also had to update my Better Figures & Images plugin to take this into account.

Previously, I’d been linking to my images like this, both in my theme:

/* Theme CSS Image Link */
background: #2C71B8 url(/static/images/blueprint-background.png) repeat;
{# Theme HTML/Jinja image link #}
<meta name="twitter:image" content …
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Compressing Limited Colour PNG images

Most of the .PNG files on this site are the ‘blueprint’ style diagrams, like this one:

Blueprint style diagram showing an optical microscope. The sample inside is magnified in a bubble to 2500 times
Figure 1. This illustration is a large 5.6MB SVG file, mostly because of the very detailed paisley pattern that I used. Exported to PNG - and then compressed using the process below, you can get this down to 118.5kB.

I create these in Inkscape as vector .SVG files & export them to bitmap .PNG files. I then re-compress them, to ensure that the image files that are used on the live website are as small & quick to load as possible.

As these diagrams have a fairly limited colour palette, I can get lots of extra compression by reducing the colour depth of the final .PNG files from the default 32bit (millions of colours) to 8bit (256 colours) - without any …

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reddit bots diagram
Figure 1. How much does a software bot weigh, anyway? Heavily modified & adapted from the original public domain robot on openclipart, posted by johnny_automatic.

reddit, the insanely popular internet community, had 71,435,935 unique visitors last month, with over 2,360,783 people logged in [1].

I say people - but it turns out that not all the denizens of reddit are human. There are also bots. Lots and lots of bots. How many? No-one really knows. [2]

This is an interesting and somewhat shadowy facet of the otherwise very public reddit community, so I thought I’d take a closer look…​

What is a reddit bot?

A reddit bot is no different from any other user, as far as reddit is concerned. The only difference is that rather than a human logging in to upvote cat pictures and post …

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As I mentioned previously, this site was put together using Pelican - a static site generator, written in Python.

Blueprint style diagram showing a brown Pelican
Figure 1. Pelecanus Occidentalis - the Brown Pelican. Original clipart Flying Pelican from OpenClipart, by molumen, Public Domain. More on Pelican, the bird.

Static site generators take your content, pour it into your templates and output the result as static pre-generated HTML, CSS, JS & image files. You can then just upload the resulting folder of output to your server and you’re done. All you need on the server is a web server of some sort, like Apache or Nginx - anything really - all it’s doing is serving static pages.

The huge advantage of this setup is simplicity:

  1. You can write your content in Markdown [1], reStructuredText [2] or AsciiDoc [3] - all simple text formats, designed to facilitate writing and get out of …
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