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Monthly Meanderings: July 2026

2026-08-01T00:00:00Z

Another month, another roundup post. This month has been very… exercise-y. Which is, for the record, not normal for me. For the previous year my only source of exercise has basically been walking, but that’s not a great fitness activity for me. When my regular walks entered the 10-15km territory it got more and more annoying to find the time and/or an interesting route.

I also managed to injure my knee while walking through a particularly muddy field, and spent a few months going slightly stir crazy. Coming out of that I started running three times a week, bought a bicycle, and added in some strength exercises along with the ones the physio recommended. If you told me a few months ago that I’d be annoyed at not being able to exercise too much on rest days I’d think you were mad.

Website updates and other projects

Before we talk even more about exercise, let’s do the usual topics I cover in these posts. The only website update this month has been a post about… exercise. Maybe I have a problem. Anyway, in Tracking PBs without the dark patterns I talk about building a slimmed-down, single-player Strava to track my personal bests, without all the nonsense that annoys me.

Other than the PB tracker, I’ve not been working much on personal projects. I’ve not really had any other itches that need scratching, just the usual background noise of dependency updates and other project maintenance.

Entertainment

Behold, the section where I normally talk about the films, TV programmes, and board games that have kept me entertained this month: […]. Yep, not a single one.

I have played a few games, though. A friend and I finally got around to trying out Escape Simulator 2, and it’s just as good as the original. The rooms feel a bit more detailed, and there are a few cool interactions that probably wouldn’t be possible in the old version. There’s also a hard mode for all the rooms which we’ve not yet tried, but sounds like it’ll keep us amused for a bit longer.

I’ve also been playing a bit of World of Warcraft, but it’s now in the awkward stage where I’ve done most things I can reasonably do this season, and there’s not really any point in doing anything else. All the gear will become mostly irrelevant in a few weeks when season two releases, and we’ve hit the major milestone achievements for Mythic+. Feels a bit anticlimactic to get to a fairly good stage and then just… not play for a bit.

Fitness

Given how much exercise I’ve done, it probably deserves its own section in these monthly posts. I have the vague idea of aiming to run a marathon before I turn 40 (i.e., within around 15 months). That’s both scary and yet not completely impossible. I’m going to work up through the distances and see how it goes. A 5k at the start of September, 10k in November, half marathon around Easter next year, then a full marathon just before my birthday in October. That way even if it gets too tough or something goes wrong I’ll have accomplished something.

New hobbies mean new toys. My bike is nothing particularly special: a hybrid from Halfords that’s about one step up from entry-level. But it gets the job done, and has helped me remember how much I enjoy cycling. The infrastructure around here is pretty terrible, though. There are lots of little bits of multi-use paths and a few dedicated bike lanes, but they’re not joined up or signed well in the slightest. In most cases it’s easier to just stay on the road and deal with the traffic. It’s a bit sad that they’ve spent time and money to do something and it’s not very useful.

On the running side, I picked up a Garmin Forerunner 165 watch. I’ve been wearing an Apple Watch for a little over a year now, but using the touchscreen to navigate screens and start/stop activities while running is annoyingly fiddly. The digital crown keeps getting gummed up with sunscreen and requiring cleaning, too. The Forerunner has physical buttons, and is much better at showing the data I want to see in a clear format, and letting me set things up like target pace or distance on the watch itself, instead of via a phone app. Oh, and the battery seems like it’s going to last for a week rather than a day, which is a nice change of pace.

I’m going to need to make a nice widget to show off my monthly runs and bike rides, but for now here’s some artisanal stats:

I went out for 14 runs, totalling 48km, although a significant portion of that was walking for warmup, cooldown or recovery.
My longest actual run was a 20 minute straight run covering 2.5km.
My average running pace is 8min/km, which is a “conversational” pace for me right now.
I went for 9 cycle rides: 2 on rented mountain bikes, then the rest on my own bike. They covered 128km.
When cycling I made 8 coffee shop stops, which works out to exactly one every 16km on average.

Next month I’m hoping to ramp the running up to hit 5k by the very end. I’m mostly following the NHS Couch to 5k plan but I’m tweaking it a little bit as otherwise I’d finish on 3.75km at my current pace. I guess “Couch to 30 minutes of running” isn’t quite as catchy. I made a Couch to 5k page to track my progress and adjustments.

Around the web

Blogging Can Just Be Stating The Obvious

I often look at my own posts and think, “There’s nothing novel, or important, or deep in here at all — is this even worth saying?”

I’ve written before about The Curse of Knowledge and Blogging, and this is a very similar take from Jim Nielsen, but it’s still super interesting to see a similar idea expressed in another way by another person.

I Built a Voice Opening Door to Moria (My Garage)

A YouTube video documenting a really cool project. What grabs me is the amount of disciplines he dabbles in: he’s part blacksmith, part carpenter, part electrician, part programmer, and so on. It’s one of the best examples of maker culture I’ve seen in ages.

There’s one bit in particular that sticks in my mind: he tried to find a rendering of the door online, and realised all the existing ones were gibberish or illegible, so he downloaded a font and worked out the exact inscription himself. It makes my inner perfectionist feel validated.

Linus Torvalds on AI in the Linux kernel

LLMs are very divisive, and there are a lot of unsettled moral and ethical issues. But at the end of the day they’re a tool that’s not going to go away any time soon. There are people on crusades to try and ban LLM tools in projects, boycott any projects that accept contributions, and so on. It’s a bit like militant veganism. I can understand where they’re coming from, but also please stop shouting at me. Anyway, this take from Linus seems pretty spot on to me.

Buttons

An interactive, graphical history of how buttons have been rendered in various operating systems and desktop environments over time. Maybe it’s just my age and nostalgia, but it really does feel like they peaked around the late 90s/early 2000s. I’m not quite sure why we went from elegant skeuomorphic buttons to ugly plain squares with weird accent colours when you click them.

Rotating sandwiches

For some reason I expected this to be static pictures of sandwiches which spun in a circle, but it’s actually recordings of sandwiches rotating on a turntable. It’s oddly mesmerising. I wonder why I’ve never seen a restaurant menu with gifs like that?

Tracking PBs without the dark patterns

2026-07-23T00:00:00Z

I’ve recently been bitten by some kind of strange exercise bug. I’ve gone from being mostly sedentary to struggling to not go out for a cheeky bike ride on a day that’s meant to be a rest day. Maybe this is what a midlife crisis feels like?

Anyway, one of the things I’ve enjoyed about this development is seeing my personal best efforts gradually go up. There’s something incredibly rewarding about doing a run, and then seeing a nice little gold medal because as part of that you ran your fastest 1km ever. Unfortunately the only software I’ve found that does that is Strava, and boy do I not get on with it.

The many shortcomings of Strava

Strava is basically the app for running and cycling. Everyone talks about it. It sounds like they like it. But I really, really don’t. It’s like someone went through a catalogue of user-hostile behaviours and said “we’ll take them all!”.

The problems started in the setup wizard: it touts a load of privacy features, but doesn’t offer any way to enable them. All your activities are public by default, and you have to spelunk around in the settings to turn that off. I wasn’t actually sure if I wanted my activities to be public or not, and ended up flip-flopping around a bit. There is a clunky workflow to bulk change past activities, but it’s arbitrarily time-gated so you can’t use it too often…

The bulk operations are extremely limited, too: you can set the activity visibility, and your heart rate visibility, and that’s it. Want to bulk delete things? You’re out of luck. Bulk rename? No chance. You either do them one-by-one or use some janky third-party script. I think I pressed around 300 little ‘delete’ links in the course of trying to get my activity history imported in a way I liked.

Those problems give a bit of a signal about Strava’s priorities, but I could live with them. Once I’ve stopped faffing with the initial import I’m not really going to want to change the privacy settings or bulk edit things. Alas, the problems didn’t end there.

Look at me! Look at me! GIVE ME ENGAGEMENT!

The most obvious one is that everything is an upsell. Vast swathes of the app are premium-only, and they don’t ever get out of your way: they stick around acting as adverts. We’re all used to freemium apps that try to hawk upgrades, but the sheer amount of screen real estate taken up by these is egregious. I started a premium trial, expecting things to get a lot better, and… they didn’t really. All the premium features are still branded as such, so now instead of “look at what you could have if you paid us” it’s “look at what you’re getting for paying us (don’t even think about cancelling)”. Subscribing also makes your avatar get a premium outline, and there’s no way to disable it. I really hate that. Now I’m an advert myself. I don’t want to be part of their weird dark patterns, thank you very much.

And while we’re talking about dark patterns: there’s so much engagement bait that I physically cringe at it. You get a notification for logging an activity with a vague call to action to check it out. You get a separate notification when you break or come close to one of your PBs, but it doesn’t tell you which; there’s plenty of space in the notification for it, but they want you to hit the app instead. It all just feels so slimy to me. I don’t know whether it doesn’t bother other people as much, or if they’re desensitised to it, or just don’t realise how pleasant things could actually be.

Making a replacement

I realised pretty early on that if I only want automatic PB tracking, I could just write something myself to do it. I already use Health Auto Export to exfiltrate data from Apple Health, including workouts. I can just make a service that receives that data, crunches some numbers, and activates the dopamine receivers in my brain when I set a new record. But I didn’t really want to bother doing that if I could avoid it. I tried a whole slew of different apps and none of them did the thing, at least not without a subscription. And Strava had soured me on fitness subscriptions. I finally resigned myself to making something.

And by “myself” I mean “an LLM”. This is one of the first projects where I’ve not written a single line of code, and I’ve barely even reviewed anything produced by the LLM. I gave it an overall architecture and some sample data, and had it write a plan. I critiqued the plan, had it broken down into a few different phases, and then had it work through them. I occasionally stopped it when I saw it doing something stupid, and gave it a couple of technical steers, but my feedback has mostly been functional. I’m probably not going to be releasing it publicly any time soon for that reason — I don’t want to publish it under my name when I’ve not even looked at the code. I also wouldn’t be comfortable making software this way if other people were going to rely on it, but for non-critical, personal-use-only software I’m happy with the approach.

Anyway, I called it “Pompei Band”. Project names are hard. One of my common techniques is to put a term into an anagram finder; in this case “PB dopamine” anagrams to “Pompei Band”, and it even abbreviates to PB. Weird, but I like it. This is how it shows recent activities on the homepage:

Dashboard entry for a recent run in PB

You can click through to see the standard activity details most tracking apps show: a map, heart rate, pace, gradient, and heart rate zones. You can also click on each effort to see a history of them, which gives a nice overview of progress:

1 mile run PB history

It pretty much does exactly what I want, and has none of the annoying behaviours that Strava leans into. When I first drafted this post I wrote “there’s a few more bits I’d like to add at some point, but I can happily prompt them into existence when I want them”, but in the time I spent procrastinating before taking screenshots I ended up implementing them all. My favourite is this little history widget I added to the homepage, shown here next to Strava’s:

Recent activity calendar in Pompei Band and in Strava

The Strava one just confuses me. I’m not sure what the scale of the circles means. I’m guessing it’s time, which in effect means it just highlights my bike rides which are longer than runs. The colours for the line charts don’t work for me, and I’m not sure what three zig-zag lines are meant to represent. Pompei Band’s version uses distinct, obvious colours for different activities, and scales the brightness independently for each type of activity based on length (so long cycle rides don’t affect the short runs). I also flipped the axes so it looks more like a GitHub activity timeline, because that’s how my brain works. Nothing groundbreaking, but also none of the paper-cuts the Strava version inflicted on me.

Software doesn’t have to be awful

This blog post has been rattling around in my head for a few days. I didn’t want it to just be a litany about Strava being bad, and I didn’t want to sound like an LLM hype piece, which made it tricky to figure out what I was actually trying to say. I think the core of it is: software doesn’t have to be awful.

Everyone’s heard of enshittification, and it’s so prevalent that it’s easy to accept it as a fact of life. That’s just how late-stage capitalism works, right? But we can just make better software. And as LLMs slowly become more and more capable, that “we” grows to a broader and broader group. It’s easy to be negative about that: we’re going to drown in vibe-coded products, much like we’re already drowning in written LLM slop. On the other hand, a future where you can just say “make me single-player Strava without all the dark patterns” and get something that works just how you want it is pretty exciting.

The one thing I can’t decide: if everyone can whip up their own individual software, will the existing platforms actually improve? If Strava didn’t have all the dark patterns and engagement bait I would have just have paid for it. Will they realise that? Or will they double down even harder, try to lock you into their platform, and build moats around user data? Now I’ve said it, it seems pretty obvious they’ll try to do that. But I hope they won’t.

Monthly Meanderings: March 2026

2026-04-01T00:00:00Z

Since last month’s update I’ve been unpleasantly reminded that I’m middle aged, through the medium of a dodgy knee. There’s nothing quite like not being able to stand up without groaning to underscore that you’re not young any more. The ongoing game of “will this seemingly mundane activity make my knee go funny again?” is a delight to play, too. I’m great at it.

Website updates

Two new blog posts this month: the longest way to represent a date is a short thought experiment on absurd date formats, and modern CSS is fun goes through some neat new CSS features I’ve used recently for this site.

I did some design tweaks this month: headers now have a blue background behind them¹, and a lot of components have been redesigned to have a consistent style. You can see that component in action in the new “now playing” widget I’ve added:

Lil Nas X — Old Town Road (remix) 7 Scrobbled 51m ago

Instead of each component defining its own styles (which were mostly copied and pasted), there’s now a single class that handles the drop shadow, border, background colour, and the optional title. It also applies a consistent format to elements that are clickable: they use the blue accent colour for their borders, and have a glow effect shown on hover.

The now playing widget is part of a larger bit of work I did on importing some music stats. I’m pulling in the data from my Navidrome instance. A new music page shows my most listened albums and artists. Navidrome doesn’t store a complete play history, just the last play and the count, so I can’t do “what I listened to last month” stats until next month.

Other projects

Other than a minor bug-fix update to contempt, my Dockerfile templating/updating tool, I’ve not done much on my other open source projects. I’ve got a bit more work to do finish migrating all my repositories from GitHub to my private Forgejo instance. I’ve also been thinking about mirroring my public repositories to Codeberg so there’s a non-GitHub way to access them.

Entertainment

I apparently only watched a single film in March:

The Substance

2026-03-18

I really didn’t get on with this. It’s too long for what it is, and over-the-top in a way that just didn’t work for me.

Demi Moore and Margaret Qualley were great, but nothing else really was. The cinematography and sound design were too affected, the plot was pretty shallow and obvious, most of the body horror fell into the uncanny CGI valley for me.

It’s not completely without merit: there were around 40 minutes in the middle where I was really into it, but that’s not really enough given it’s closing in on a 2.5 hour runtime.

There’s something to be said for the message it’s presenting about women in Hollywood, too, but it was very heavy handed. Dennis Quaid’s character is even called Harvey; it’s not so much a subtle nod as a sledgehammer to the face.

Instead of films, I’ve been watching a bunch of TV. After devouring The Pitt last month, I struggled to find something to fill the hole it left. I settled on catching up on Chicago Fire and Chicago P.D.. They’re both mostly about getting things done without personal drama becoming the primary focus. They’re not quite as grounded as The Pitt, but at least they’ve not completely gone off the deep end like 9-1-1 where the first responders end up in space somehow?

I’ve also watched the first two episodes of SNL UK. I didn’t have very high expectations, and it gave me a pleasant surprise. Both episodes so far have some hilarious sketches, and are obviously written by British comics with the typical darker, more sardonic humour that separates us from the USA.

Last but not least, board games! I spent a weekend at a tabletop/LAN event with friends, so got to physically play some games for a change. I also kept up with some turn-based games on Board Game Arena, as usual.

6 plays
4 plays
4 plays
4 plays
3 plays
3 plays
3 plays
2 plays
2 plays
2 plays
2 plays
2 plays
1 play

Around the web

Warranty Void if Regenerated

Some really cool speculative fiction about a future where all software is written by LLMs, and the social effects that may have. Unfortunately the story itself is written with an LLM, and that becomes painfully obvious about a third of the way in. By that point I was already hooked, though.

My 2-step process for AI-free blogging

Speaking of LLM-generated text, this short piece by Manuel Moreale made me laugh. I’m by no means anti-LLM, but I really hate people publishing the output like it’s their own work. It breaks the social assumption that the writer put more effort in than the reader, and makes me wonder how much is hallucinated.

25 Years of Eggs

An interesting applied use of coding agents. I’m a sucker for personal statistics. I have no explicit desire to keep my receipts, or generate graphs of my egg consumption, but seeing the graphs makes me question that. The journey to get there is a great read, too.

I made a one-page notebook

The clever paper folding is interesting, but I really like some of the small touches on the page. There’s a nice little “in reply to” callout providing context at the top of the page, you can click to rotate the image further down, and there’s a details element containing a textual version of it. It has that great ‘small web’ vibe of someone who really cares about what they’re doing.

Workers who love ‘synergizing paradigms’ might be bad at their jobs

I haven’t read the full paper, but the summary given by the article is equal parts interesting and amusing. They developed a “Corporate Bullshit Receptivity Scale”, what more is there to say?

It’s meant to resemble painter’s tape, but I’m not sure quite how well it works. ↩︎

Modern CSS is fun

2026-03-17T00:00:00Z

I’ve been doing a bunch of CSS tweaking recently, and keep being surprised by how nice modern CSS is to work with. As someone grey-haired enough to remember writing HTML without CSS, it’s amazing to think how far along web technology has come¹. I wanted to demonstrate some of the handy bits and pieces I’ve used recently.

:has

The :has selector allows you to effectively query for child elements. While a span will match a <span> within an <a>, a:has(span) will match an <a> that contains a <span>. This really shines when combined with more complex selectors, for example:

input {
    border-radius: var(--border-radius);

    &:has(+ .results:not(:empty)) {
        border-bottom-left-radius: 0;
        border-bottom-right-radius: 0;
    }
}

This is part of the styling for my film search box. When the search box is presented initially it has fully rounded corners. But when it is followed by a non-empty results element, it removes the rounding on the bottom corners so that the border continues in a straight line down into the results. You can see it in action below; just enter a few characters (like “the”) to get some results:

You could achieve the same effect by having JavaScript add a class to the <input> element, but I’ll take a CSS solution over a JavaScript solution any day.

Nested rules

You probably spotted this in the example above. It’s what finally made me switch from SCSS to plain CSS. If you have a rule for .foo and a rule for .foo .bar you can just nest them. Not only does it save repeating yourself an awful lot, it keeps everything organised nicely. For example, the CSS for my film list embeds looks like this:

a.film-list {
    display: grid;
    grid-template-areas: "header images" "description images" "meta images";
    grid-template-columns: 1fr auto;
    grid-template-rows: auto 1fr auto;
    row-gap: var(--small-space);

    @media (width <= 800px) {
        grid-template-areas: "header" "description" "images" "meta";
        grid-template-columns: 1fr;
        grid-template-rows: auto auto auto auto;
    }

    & + & {
        margin-top: var(--medium-space);
    }

    h3 {
        font-size: var(--font-size-xxlarge);
    }

    .description {
        /* ... */
    }
}

Everything is wrapped up in a single bundle, including the @media rules for changing the layout on smaller screens, the lovely little & + & rule that adds some extra margin if there are two lists in a row, etc. The & syntax refers to the parent selector, so & + & in this case is the same as a.film-list + a.film-list: it’s very handy! The best part about this is that it’s the exact same syntax as SCSS, so converting is easy². The styled element looks like this:

Watched films ranked

Every film I’ve watched since I started logging, ranked.

Obviously super subjective, and subject to change often and arbitrarily.

264 films

Media range syntax

Once again, you might have spotted this in the previous snippet. I’m not deliberately teasing things, I promise! Back in the day, you did media queries like so:

@media (min-width: 1000px) and (max-width: 2000px) {
    /* some rules that work for screens at least 1000px wide and at most 2000px wide */
}

I always hated this syntax. I always got muddled up as to whether I wanted “min” or “max”, and whether they were inclusive or not. It’s easy to reason through, but it never came naturally. Fortunately you can now just use ranges:

@media (1000px <= width <= 2000px) {
    /* some rules that work for screens at least 1000px wide and at most 2000px wide */
}

I find this style so much easier to write and understand.

Anchor positioning

Trying to dynamically position one element next to another used to exclusively fall within the purview of JavaScript. Fortunately anchor positioning fixes all this. I use this in the film search field I showed above:

.film-search {
    input {
        anchor-name: --film-search-box;
    }
    .results {
        position: absolute;
        position-anchor: --film-search-box;
        position-area: bottom center;
        position-visibility: always;
        width: anchor-size();
    }
}

This does lots of fun things. The .results element is anchored to the input field (via the --film-search-box name), and it’s positioned on the bottom, directly under the anchor. The position-area rule describes a 3x3 grid, with the anchor at the center, so top left would put it diagonally adjacent to the anchor. Next, position-visibility keeps the .results element visible when the anchor isn’t; otherwise when you scroll the anchor off the screen the results would immediately vanish. Finally, the special anchor-size() function makes the .results element take up the same exact width as the anchor.

All-in-all, this puts the results exactly where I want them, without having to deal with any JavaScript at all. I can see how it’d also be amazingly useful trying to do tooltips or other forms of ‘floating’ content too. You can even leave the positioning up to the browser, giving it hints about which order to try, or what property to optimise for (e.g. you can say “anchor to the left or right, whichever has more horizontal space”).

attr() function

This one blew my mind a little. In some of the elements on the site, I’ve added a little label to the top. It looks something like this:

It’s meant to just be a visual flourish, not a semantic title or anything, so I initially just added a ::before selector to each element, customising the content to have the right value. I didn’t like the duplication, though. Now, instead, I do this:

&::before {
    content: attr(data-title);
}

Each component defines its title in a data attribute: <div class="raised-box" data-title="an example">, and the attr function plucks it out and puts it in the content rule. It’s worth noting that this is only widely supported for the content rule, you can’t yet use it for colours or dimensions or other things. It still feels a bit magical, though. Like you’re making a reusable, customisable component with just HTML and CSS.

layers

I’d come across layers a few times, but I never found a need for them. It seemed like something you’d only really need with complicated design systems, or something. Then I had a problem and layers were the perfect solution!

The headings on this site have a whole bunch of CSS attached to them. Currently they look a bit like blue painter’s tape with handwriting on them. This style is applied to all headers, and then the various places that don’t want it had to manually reset everything. I got fed up with that, so decided to add a plain-header class which would “disable” the extra styling:

h2,
h3,
h4,
h5,
h6 {
    /* common styles for all headers, regardless */
    font-family: "Chris Hand", sans-serif;
    font-size: var(--font-size-xxlarge);
    color: var(--text-highlight-colour);
    margin: var(--medium-space) 0;
    line-height: 1;

    &:not(.plain-header) {
        /* do fancy stuff if it _doesn't_ have the .plain-header class */
        transform: rotate(-0.15deg);
        padding: var(--smedium-space);
        font-weight: 800;
        filter: drop-shadow(3px 3px 5px rgb(0, 0, 0));

        a {
            background: none;
            text-decoration-skip-ink: auto;
        }
    }
}

This might seem a bit backwards but I want the default to be styled, as those are far more common. I added this change, sprinkled around some “plain-header” classes, tidied up a lot of duplicate CSS, and things mostly worked. Mostly. Some things stopped working. In a few places the headers had slight tweaks, and they stopped working entirely.

It turns out in moving the rules from a plain h2 selector to a h2:not(.plain-header), I’d made them more specific. Previously a selector like h2.special would have been more specific, so its properties would override those from the less specific h2 selector. My first reaction was to try and hack around it. Changing all the overrides to body h2.special would make them more specific again, but I didn’t want to have to remember to do that forever more.

Instead, I defined some custom layers, and put the header definitions in one:

@layer reset, links, headings

@layer headings {
    h2,
    h3 {
        /* etc */
    }
}

The first @layer rule defines some layers that will be handled in a specific order: first the “reset” layer, then the “links” layer, then the “headings” layer, and then anything not in a layer after that. Rules in one layer don’t have to worry about beating the specificity of rules in another layer, because they’re handled separately.

Note that I couldn’t just put the headings in a layer and call it a day: their rules have to come after the CSS reset, and after the normal link styles, as headers have a bit of extra styling for nested links. If the CSS reset weren’t in a layer, then the * { margin: 0; padding: 0; } type reset would apply over the rules from the headings layer.

Using layers is definitely a bit fiddly, and is not necessary for a lot of sites, but it’s a much cleaner alternative to ugly specificity hacking.

Things I’m looking forward to

There are a few things that aren’t (widely) available yet, that particularly interest me:

sibling-index() and sibling-count()

These new functions are available in WebKit and Blink based browsers, but not Firefox. They give you the index of the element within its siblings, or the count of siblings. For the film list component above, I currently have this abomination for the overlapping posters:

&:nth-child(1) {
    z-index: 5;
    left: 0;
}
&:nth-child(2) {
    z-index: 4;
    left: calc(133px * var(--overlap) * 1);
}
&:nth-child(3) {
    z-index: 3;
    left: calc(133px * var(--overlap) * 2);
}
&:nth-child(4) {
    z-index: 2;
    left: calc(133px * var(--overlap) * 3);
}
&:nth-child(5) {
    z-index: 1;
    left: calc(133px * var(--overlap) * 4);
}

These could be replaced with something like:

z-index: calc(1 + sibling-count() - sibling-index());
left: calc(133px * var(--overlap) * (sibling-index() - 1));

As an added bonus, it would scale to any number of posters. index being 1-based not 0-based is a bit unfortunate as it makes using it in calculations awkward (see 1 offset in both of those rules!), but it’s leagues better than writing 5 separate rules.

random()

Currently only available in Safari. There are a few places where I’d like to have slight random variations of the style. Things like elements that are rotated slightly for aesthetics; they look a bit silly if they’re all identically positioned. I also randomise the icons and positions of my rating stars to break up the visual monotony. Here are a few examples:

Currently I do the stars by hardcoding a bunch of classes and having the backend randomly apply one when it generates the markup for stars. Being able to do it in CSS would be great, though.

Mixins

This one’s so far off it’s not even listed on caniuse.com yet. Mixins are another handy feature of SCSS, that allow you to define reusable blocks of rules, then import them when needed:

@mixin fancy-background {
    background: /*...*/;
}

.some-element {
    @include fancy-background;
}

#other-element {
    @include fancy-background;
}

This would be particularly useful if you can’t easily control the markup to add classes to everything. For example, my footnotes are rendered by a markdown plugin, and don’t easily have a way to add extra classes to them. To style it the same as another element, I currently duplicate a bunch of rules between them both. Mixins would allow me to define those rules once, and then import them in both places.

Aside from JavaScript, which seems to just endlessly reinvent new frameworks and ways to make the most sprawling dependency tree possible. ↩︎
It also means that if your website’s syntax highlighting library doesn’t seem to understand nested rules, you can just pretend your perfectly valid CSS is actually SCSS and it’ll magically work. Grumble, grumble. ↩︎

An interesting Tailscale + Docker gotcha

2026-01-29T00:00:00Z

As I’ve written about before, I use Tailscale for a lot of things. I thought I had it set up in a reasonably secure manner, but I recently noticed a problem.

I use Tailscale’s ACLs to limit what each node can access, based on the tags I apply to it. So an app node can’t access anything via Tailscale, while an integration or server node can access things tagged with either app or integration. This is expressed pretty simply in the Tailscale ACL JSON:

{
	"tagOwners": {
		// Servers that can be SSH'd into
		"tag:server": [],
		// Applications that are exposed on tailscale but never connect out
		"tag:app": [],
		// Things which talk to other services over tailscale (connecting to apps etc)
		"tag:integration": [],
	},
	"grants": [
		{
			// Users can access everything
			"src": ["autogroup:member"],
			"dst": ["*"],
			"ip":  ["*"],
		},
		{
			// Servers and integrations can access integrations and apps
			"src": ["tag:server", "tag:integration"],
			"dst": ["tag:integration", "tag:app"],
			"ip":  ["*"],
		},
	],
}

Over the past week I’ve been setting up a private Forgejo instance behind Tailscale, complete with an actions runner that runs things using a docker-in-docker container. I didn’t want the runner knowing anything about Tailscale, so I had it configured to speak to Forgejo direct over HTTP (forgejo:3000) instead of using full Tailscale HTTPS URL that I use when accessing it (http://git.example-net.ts.net/)¹.

Everything was going fine, until I forgot to do that translation… and it worked. My Forgejo action runners could access anything on my tailnet. I run several things on Tailscale that just have authentication turned off, on the basis that only authorised devices can access them. Things like the admin interface for this website. I definitely didn’t intend for any workflow I run on my git server to have access to edit my website!

This wasn’t just limited to Forgejo, either. Any docker container I was running could access the tailnet. In hindsight it’s fairly obvious why: the host is running Tailscale, connected as a node tagged with my server tag. That creates a tailscale0 interface, and automagically sets up iptables rules to route Tailscale traffic over the interface. Docker also automagically sets up iptables rules to bridge traffic, and apparently these two sets of rules interact in such a way that traffic from Docker containers is allowed to route via the tailscale0 interface.

I say it’s fairly obvious in hindsight — there’s no reason why Docker would special case any particular host interface after all — but it still feels pretty surprising. Because both bits of software inject their own iptables rules, I never really had a good mental model for how they interact. The host Tailscale node was a completely separate building block to Docker. It would be a pain to use either of them if they didn’t do these rules, but it’s also one of the reasons I don’t really like “magical” things².

There are lots of ways to fix this, but none of them feel particularly great. You can configure both Tailscale and Docker to not automatically fiddle with iptables and handle the rules yourself, but I really hate dealing with iptables³. As a stopgap I did hold my nose and add some iptables rules to drop traffic to the tailscale0 interface if it originated from the IP ranges that Docker was configured to use:

iptables -I DOCKER-USER -s 192.168.0.0/16 -o tailscale0 -j DROP
iptables -I DOCKER-USER -s 172.17.0.0/12 -o tailscale0 -j DROP

The DOCKER-USER chain is a nice little escape hatch; it comes before the main auto-generated DOCKER chain, and Docker leaves the rules in it alone.

So I added these rules, and felt pretty good about myself, and then… everything started breaking in weird ways. After some debugging I realised the problem was DNS⁴. The server’s DNS resolver is 100.100.100.100, a special Tailscale address. This is so that it can resolve tailnet hostnames via MagicDNS (and so I don’t have to configure my custom DNS servers manually on each device; Tailscale does it for me). My new iptables rules inadvertently dropped all the DNS packets coming from docker containers. D’oh.

Obviously the solution here is to double down and add MORE iptables rules:

iptables -I DOCKER-USER -s 192.168.0.0/16 -d 100.100.100.100 -o tailscale0 -j ACCEPT
iptables -I DOCKER-USER -s 172.17.0.0/12 -d 100.100.100.100 -o tailscale0 -j ACCEPT

This got DNS working again, but it all feels a bit gross. Not least because to actually make these persist you need to use iptables-save, and then you also get all the rules that both Docker and Tailscale have inserted. I came across a script to filter out the Docker ones, but… yuck⁵.

I realised a cleaner idea might just be to lock down what server tagged nodes could access within Tailscale itself. That way I can avoid touching iptables at all. It’s handy to be able to curl services from the host when debugging, but it’s not really necessary. So I removed that access, and… stuff broke again. I’m using my Forgejo instance as a registry for some of the docker images I run, so the docker daemon needs to be able to reach it. I ended up making a new tag for infrastructure, which can be accessed from server devices. This does still allow all the docker containers to reach Forgejo, but I already have it set up with appropriate access controls and public/private repository splits. Forgejo is a service designed to run publicly, so this seems a reasonable trade-off for convenience. I used the tests feature of Tailscale’s ACL config to make sure I’d got the rules right:

{
	"tests": [
		{
			// Servers can only access infrastructure
			"src":   "tag:server",
			"proto": "tcp",
			"allow": [
				"tag:infrastructure:8080",
			],
			"deny": [
				"100.84.16.43:8080",
				"me@example.com:8080",
				"tag:server:8080",
				"tag:app:8080",
				"tag:integration:8080",
			],
		},
	],
}

The whole situation still feels a bit messy. If I ever get around to switching to nftables I might loop back and manually craft some rules for routing traffic, instead of leaving Tailscale and Docker to do their own thing.

I discovered later on that logging into the container registry at forgejo:3000 actually issued a redirect to https://git.example-net.ts.net/ so this was all basically for naught… ↩︎
I didn’t use Tailscale’s MagicDNS for a long time just because the word “magic” put me off. Only when I eventually got around to learning how it worked, and seeing that it wasn’t really that magical under the hood, did I change my mind. ↩︎
nftables seems far better in lots of ways, but I can’t really be bothered migrating. Maybe next time I reimage the server for whatever reason… ↩︎
It’s always DNS… ↩︎
Again, nftables would almost certainly help here. It actually has (gasp) configuration files. But again, I really didn’t want to spend the time migrating. ↩︎