new post: Dark mode for the ages

_posts/2024-05-18-dark-mode-for-the-ages.md

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+---
+permalink: "/{{ year }}/{{ month }}/{{ day }}/dark-mode-for-the-ages"
+title: "Dark mode for the ages"
+published_date: "2024-05-18 13:23:00 +0200"
+layout: post.liquid
+data:
+  route: blog
+excerpt: |
+  blub
+---
+
+They say projects are not finished until you write about them.
+So here we go.
+
+Last night I was still up and awake at 2 am.
+I opened this website and ... BOOM ... bright light in my eyes.
+I do like this site's simple colorscheme,
+but when everything around you is dark it does kinda burn in your eyes.
+So I did what anyone who can't sleep at that hour does:
+I went on the internet, looked up how to change colors in CSS and implemented a theme toggle on my website (Look for the sun or moon on the top right!)
+
+There's many articles on this topic, the one I found was
+[The simplest CSS variable dark mode theme][theme-switcher] by Luke Lowrey.
+
+My site is a very simple plain ol' HTML & CSS page.
+I use [Writ] as the base style and provide just a few things on top in my [style.css].
+The colors are now defined like this:
+
+```css
+:root,
+html[data-theme='light'] {
+  --main-bg-color: white;
+  --text-color: #111;
+  --alt-text-color: black;
+  --code-bg: rgba(0,0,0,.05);;
+  --border-color: rgba(0,0,0,.05);
+  --link-color: #00e;
+  --link-color-visited: #60b;
+  --inline-code: #111;
+}
+
+html[data-theme='dark'] {
+  --main-bg-color: #111;
+  --text-color: #b3b3b3;
+  --alt-text-color: #999999;
+  --code-bg: #ccc;
+  --border-color: #414141;
+  --link-color: #478be6;
+  --link-color-visited: #c988ff;
+  --inline-code: #323232;
+}
+```
+
+and then used with `var(--main-bg-color)` further below.
+
+The theme toggle button requires a bit of JavaScript, which I straight out copied from Luke's blogpost (and put into [theme.js]).
+
+```javascript
+var toggle = document.getElementById("theme-toggle");
+
+var storedTheme = localStorage.getItem('theme') || (window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light");
+if (storedTheme) {
+    document.documentElement.setAttribute('data-theme', storedTheme)
+}
+
+toggle.onclick = function() {
+  var currentTheme = document.documentElement.getAttribute("data-theme");
+  var targetTheme = "light";
+
+  if (currentTheme === "light") {
+    targetTheme = "dark";
+  }
+
+  document.documentElement.setAttribute('data-theme', targetTheme)
+  localStorage.setItem('theme', targetTheme);
+};
+```
+
+It stores the user's preference in local storage and defaults to the system's prefered color scheme (see [`prefers-color-scheme`][mdn]).
+
+Once I had it all in place I realized I've been testing the colors with my macOS' Night Shift mode on.
+Oh well, looks good with it on, looks still decent with it off I guess.
+The dark theme is not perfect and probably could use a bit more contrast.
+Code blocks look odd as they are essentially still light mode (just slightly dimmed),
+because the current code syntax highlighting does the styling inline
+and so it's a bit hard to overwrite that in the external CSS.
+But I decided it's better to ship the 80% solution then never get to shipping at all.
+
+
+[theme-switcher]: https://lukelowrey.com/css-variable-theme-switcher/
+[writ]: https://writ.cmcenroe.me/
+[style.css]: https://fnordig.de/style.css
+[theme.js]: https://fnordig.de/theme.js
+[mdn]: https://developer.mozilla.org/en-US/docs/Web/CSS/@media/prefers-color-scheme