diff --git a/assets/css/torchlight.css b/assets/css/torchlight.css
index 5def64b..a864f1a 100644
--- a/assets/css/torchlight.css
+++ b/assets/css/torchlight.css
@@ -126,17 +126,17 @@ opacity: 1;
 Insert prompt indicators on interactive shells.
 */
 .cmd::before {
-  color: var(--base07);
+  color: var(--user-prompt);
   content: "$ ";
 }
 
 .cmd_root::before {
-  color: var(--base08);
+  color: var(--root-prompt);
   content: "# ";
 }
 
 .cmd_pwsh::before {
-  color: var(--base07);
+  color: var(--user-prompt);
   content: "PS> ";
 }
 
diff --git a/assets/js/set-theme.js b/assets/js/set-theme.js
new file mode 100644
index 0000000..5ee4ac4
--- /dev/null
+++ b/assets/js/set-theme.js
@@ -0,0 +1,40 @@
+const toggleButton = document.getElementById('themeToggle');
+const htmlElement = document.documentElement;
+
+function setTheme(theme) {
+  htmlElement.setAttribute('data-theme', theme);
+  localStorage.setItem('theme', theme);
+  updateToggleButton(theme);
+}
+
+function updateToggleButton(theme) {
+  toggleButton.setAttribute('aria-checked', theme === 'dark');
+}
+
+function getPreferredTheme() {
+  const storedTheme = localStorage.getItem('theme');
+  if (storedTheme) {
+    return storedTheme;
+  }
+  return window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
+}
+
+// Ensure the toggle button state is correct on load
+document.addEventListener('DOMContentLoaded', () => {
+  updateToggleButton(getPreferredTheme());
+});
+
+// Listen for toggle button clicks
+toggleButton.addEventListener('click', () => {
+  const currentTheme = htmlElement.getAttribute('data-theme') || getPreferredTheme();
+  const newTheme = currentTheme === 'dark' ? 'light' : 'dark';
+  setTheme(newTheme);
+});
+
+// Listen for system preference changes
+window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', (e) => {
+  if (!localStorage.getItem('theme')) {
+    const newTheme = e.matches ? 'dark' : 'light';
+    setTheme(newTheme);
+  }
+});
\ No newline at end of file
diff --git a/config/_default/params.toml b/config/_default/params.toml
index d990007..5471e29 100644
--- a/config/_default/params.toml
+++ b/config/_default/params.toml
@@ -110,6 +110,7 @@ taglines = [
   "there's no place like $HOME",
   "time jumped backwards, rotating",
   "tonight we test in prod",
+  "unable to decrypt error",
   "unable to open display",
   "undefined reference to function",
   "unexpected token",
diff --git a/content/changelog.md b/content/changelog.md
index af5241a..9055be2 100644
--- a/content/changelog.md
+++ b/content/changelog.md
@@ -1,7 +1,7 @@
 ---
 title: "/changelog"
 date: "2024-05-26T21:19:08Z"
-lastmod: "2024-08-04T22:30:43Z"
+lastmod: "2024-08-15T21:21:05Z"
 description: "Maybe I should keep a log of all my site-related tinkering?"
 featured: false
 toc: false
@@ -10,6 +10,9 @@ categories: slashes
 ---
 *Running list of config/layout changes to the site. The full changelog is of course [on GitHub](https://github.com/jbowdre/runtimeterror/commits/main/).*
 
+**2024-08-15:**
+- Implemented light/dark theme toggle
+
 **2024-08-04:**
 - Dynamically build `robots.txt` based on [ai.robots.txt](https://github.com/ai-robots-txt/ai.robots.txt)
 
diff --git a/layouts/_default/single.html b/layouts/_default/single.html
index 62d73c2..1c28805 100644
--- a/layouts/_default/single.html
+++ b/layouts/_default/single.html
@@ -26,7 +26,7 @@
     {{- if and (gt $ageDays 365) (not .Params.timeless) -}}
     <br>
     <div class="notice note">
-      <p class="first notice-title"><span class="icon-notice baseline"><svg><use href="#note-notice"></use></svg></span>Technology keeps moving but this post has not.</p>
+      <p class="first notice-title"><span class="icon-notice baseline"><svg id="note-notice" viewBox="0 0 512 512" preserveAspectRatio="xMidYMid meet"><path d="M504 256c0 136.997-111.043 248-248 248S8 392.997 8 256C8 119.083 119.043 8 256 8s248 111.083 248 248zm-248 50c-25.405 0-46 20.595-46 46s20.595 46 46 46 46-20.595 46-46-20.595-46-46-46zm-43.673-165.346l7.418 136c.347 6.364 5.609 11.346 11.982 11.346h48.546c6.373 0 11.635-4.982 11.982-11.346l7.418-136c.375-6.874-5.098-12.654-11.982-12.654h-63.383c-6.884 0-12.356 5.78-11.981 12.654z"/></svg></span>Technology keeps moving but this post has not.</p>
       What you're about to read hasn't been updated in more than a year. The information may be out of date. Let me know if you see anything that needs fixing.
     </div>
     {{- end -}}
diff --git a/layouts/partials/about.html b/layouts/partials/about.html
index f78bae7..d0e4a3e 100644
--- a/layouts/partials/about.html
+++ b/layouts/partials/about.html
@@ -1,7 +1,7 @@
 {{ with .Site.Params.about }}
 <div class="aside__about">
     {{ with .logo }}<img class="about__logo" src="{{ . | absURL }}" alt="Logo">{{ end }}
-<h1 class="about__title">{{ .title }}&nbsp;<a href="/feed.xml" aria-label="RSS"><i class="fa-solid fa-square-rss"></i></a>&nbsp;</h1>
+<h1 class="about__title">{{ .title }}&nbsp;<a href="/feed.xml" aria-label="RSS"><i class="fa-solid fa-square-rss"></i></a></h1>
 {{ partial "tagline.html" . }}
 <br>
 <a href="/about/"><i class="fa-regular fa-user"></i></a>&nbsp;<a href="/about/">{{ site.Params.Author.name }}</a>
diff --git a/layouts/partials/footer.html b/layouts/partials/footer.html
index 9f713ba..d1ba2ac 100644
--- a/layouts/partials/footer.html
+++ b/layouts/partials/footer.html
@@ -15,3 +15,7 @@
   {{ $jsCopy := resources.Get "js/code-copy-button.js" | minify }}
   <script src="{{ $jsCopy.RelPermalink }}" async></script>
 {{ end }}
+
+<!-- theme switch -->
+{{ $themeToggle := resources.Get "js/set-theme.js" | minify }}
+<script src="{{ $themeToggle.RelPermalink }}"></script>
diff --git a/layouts/partials/head.html b/layouts/partials/head.html
index 113b5ee..4691e45 100644
--- a/layouts/partials/head.html
+++ b/layouts/partials/head.html
@@ -21,8 +21,20 @@
 {{ partialCached "favicon" . }}
 {{ partial "opengraph" . }}
 
+<!-- load theme preference asap -->
+<script>
+  (function() {
+    var savedTheme = localStorage.getItem('theme');
+    if (savedTheme) {
+      document.documentElement.setAttribute('data-theme', savedTheme);
+    } else if (window.matchMedia && window.matchMedia('(prefers-color-scheme: light)').matches) {
+      document.documentElement.setAttribute('data-theme', 'light');
+    }
+  })();
+</script>
+
 <!-- FontAwesome <https://fontawesome.com/> -->
-<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.1.2/css/all.min.css" integrity="sha512-1sCRPdkRXhBV2PBLUdRb4tMg1w2YPf37qatUFeS7zlBy7jJI8Lf4VHwWfZZfpXtYSLy85pkm9GaYVYMfw5BC1A==" crossorigin="anonymous" />
+<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.6.0/css/all.min.css" integrity="sha512-Kc323vGBEqzTmouAECnVceyQqyqdsSiqLQISBL29aUW4U/M7pSPA/gEUZQqv1cwx4OnYxTxve5UMg5GT6L4JJg==" crossorigin="anonymous" />
 
 <!-- ForkAwesome <https://forkaweso.me/> -->
 <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/fork-awesome@1.2.0/css/fork-awesome.min.css" integrity="sha256-XoaMnoYC5TH6/+ihMEnospgm0J1PM/nioxbOUdnM8HY=" crossorigin="anonymous">
diff --git a/layouts/partials/header.html b/layouts/partials/header.html
index 45c46ce..c3435de 100644
--- a/layouts/partials/header.html
+++ b/layouts/partials/header.html
@@ -7,4 +7,8 @@
     {{ end }}
     </ul>
 </nav>
-
+<button id="themeToggle" class="theme-toggle" aria-label="Toggle light/dark theme" title="Toggle light/dark theme">
+  <svg class="theme-toggle__icon" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512">
+      <path d="M448 256c0-106-86-192-192-192l0 384c106 0 192-86 192-192zM0 256a256 256 0 1 1 512 0A256 256 0 1 1 0 256z"/>
+  </svg>
+</button>
\ No newline at end of file
diff --git a/static/css/custom.css b/static/css/custom.css
index c7c6ddf..41d797f 100644
--- a/static/css/custom.css
+++ b/static/css/custom.css
@@ -1,9 +1,113 @@
-/* color and font overrides */
+/* define fonts */
 :root {
-  --code: var(--base06);
   --font-monospace: 'Berkeley Mono', 'IBM Plex Mono', 'Cascadia Mono', 'Roboto Mono', 'Source Code Pro', 'Fira Mono', 'Courier New', monospace;
 }
 
+/* dark/light theming */
+:root{
+  /* Default dark theme */
+  --bg: var(--dark-base00);
+  --code: var(--dark-base06);
+  --fg: var(--dark-base05);
+  --highlight: var(--dark-base0A);
+  --hover: var(--dark-base0C);
+  --inner-bg: var(--dark-base02);
+  --link: var(--dark-base0D);
+  --logo-text: var(--dark-base09);
+  --logo: var(--dark-base0B);
+  --muted: var(--dark-base03);
+  --off-bg: var(--dark-base01);
+  --off-fg: var(--dark-base04);
+  --root-prompt: var(--dark-base08);
+  --user-prompt: var(--dark-base07);
+}
+
+:root[data-theme="light"] {
+  --bg: var(--light-base00);
+  --off-bg: var(--light-base01);
+  --inner-bg: var(--light-base02);
+  --muted: var(--light-base03);
+  --off-fg: var(--light-base04);
+  --fg: var(--light-base05);
+  --code: var(--light-base06);
+  --user-prompt: var(--light-base07);
+  --root-prompt: var(--light-base08);
+  --logo-text: var(--light-base09);
+  --highlight: var(--light-base0A);
+  --logo: var(--light-base0B);
+  --hover: var(--light-base0C);
+  --link: var(--light-base0D);
+}
+
+@media (prefers-color-scheme: light) {
+  :root:not([data-theme="dark"]) {
+    --bg: var(--light-base00);
+    --off-bg: var(--light-base01);
+    --inner-bg: var(--light-base02);
+    --muted: var(--light-base03);
+    --off-fg: var(--light-base04);
+    --fg: var(--light-base05);
+    --code: var(--light-base06);
+    --user-prompt: var(--light-base07);
+    --root-prompt: var(--light-base08);
+    --logo-text: var(--light-base09);
+    --highlight: var(--light-base0A);
+    --logo: var(--light-base0B);
+    --hover: var(--light-base0C);
+    --link: var(--light-base0D);
+  }
+}
+
+body {
+  transition: background-color 0.3s ease, color 0.3s ease;
+}
+
+.theme-toggle {
+  position: absolute;
+  top: 1rem;
+  right: 1rem;
+  background: none;
+  border: none;
+  cursor: pointer;
+  padding: 0;
+  width: 2rem;
+  height: 2rem;
+  z-index: 1000;
+  transition: opacity 0.3s ease;
+}
+
+.theme-toggle:hover {
+  opacity: 0.7;
+}
+
+.theme-toggle:focus {
+  outline: none;
+}
+
+.theme-toggle:focus-visible {
+  outline: 2px solid var(--hover);
+  outline-offset: 2px;
+}
+
+.theme-toggle__icon {
+  width: 100%;
+  height: 100%;
+  transition: transform 0.3s ease, fill 0.3s ease;
+  fill: var(--off-fg);
+}
+
+.theme-toggle:hover .theme-toggle__icon {
+  fill: var(--hover);
+}
+
+[data-theme="dark"] .theme-toggle__icon {
+  transform: rotate(180deg);
+}
+
+.page__nav ul {
+  padding-right: 3rem;
+}
+
 /* load preferred font */
 @font-face {
   font-family: 'Berkeley Mono';
@@ -30,7 +134,7 @@
 
 /* logo tweaks */
 .page__logo {
-  color: var(--off-fg);
+  color: var(--logo-text);
 }
 
 .page__logo-inner {
@@ -70,59 +174,24 @@
 
 /* Notice CSS Built on hugo-notice by Nicolas Martignoni: https://github.com/martignoni/hugo-notice */
 .notice {
-  --root-color: #444;
-  --root-background: #eff;
-  --title-color: #fff;
-  --title-background: #7bd;
-  --warning-title: #c33;
-  --warning-content: #fee;
-  --info-title: #fb7;
-  --info-content: #fec;
-  --note-title: #6be;
-  --note-content: #e7f2fa;
-  --tip-title: #5a5;
-  --tip-content: #efe;
-}
+  --notice-title-color: #fff;
+  --notice-warn-color: #c33;
+  --notice-info-color: #fb7;
+  --notice-note-color: #6be;
+  --notice-tip-color: #5a5;
 
-@media (prefers-color-scheme: dark) {
-  .notice {
-    --root-color: #ddd;
-    --root-background: #eff;
-    --title-color: #fff;
-    --title-background: #7bd;
-    --warning-title: #800;
-    --warning-content: #400;
-    --info-title: #a50;
-    --info-content: #420;
-    --note-title: #069;
-    --note-content: #023;
-    --tip-title: #363;
-    --tip-content: #121;
-  }
-}
+  --notice-padding: 18px;
+  --notice-line-height: 24px;
+  --notice-margin-bottom: 24px;
+  --notice-border-radius: 4px;
+  --notice-title-margin: 12px;
+  --notice-bg-opacity: 10%;
 
-body.dark .notice {
-  --root-color: #ddd;
-  --root-background: #eff;
-  --title-color: #fff;
-  --title-background: #7bd;
-  --warning-title: #800;
-  --warning-content: #400;
-  --info-title: #a50;
-  --info-content: #420;
-  --note-title: #069;
-  --note-content: #023;
-  --tip-title: #363;
-  --tip-content: #121;
-}
-
-.notice {
-  padding: 18px;
-  line-height: 24px;
-  margin-bottom: 24px;
-  border-radius: 4px;
-  color: var(--root-color);
-  background: var(--root-background);
+  padding: var(--notice-padding);
+  line-height: var(--notice-line-height);
+  margin-bottom: var(--notice-margin-bottom);
+  border-radius: var(--notice-border-radius);
+  color: var(--fg);
 }
 
 .notice p:last-child {
@@ -130,45 +199,23 @@ body.dark .notice {
 }
 
 .notice-title {
-  margin: -18px -18px 12px;
-  padding: 4px 18px;
-  border-radius: 4px 4px 0 0;
+  margin: calc(-1 * var(--notice-padding));
+  margin-bottom: var(--notice-title-margin);
+  padding: 4px var(--notice-padding);
+  border-radius: var(--notice-border-radius) var(--notice-border-radius) 0 0;
   font-weight: 700;
-  color: var(--title-color);
-  background: var(--title-background);
+  color: var(--notice-title-color);
 }
 
-.notice.warning .notice-title {
-  background: var(--warning-title);
-}
+.notice.warning .notice-title { background: var(--notice-warning-color); }
+.notice.info .notice-title { background: var(--notice-info-color); }
+.notice.note .notice-title { background: var(--notice-note-color); }
+.notice.tip .notice-title { background: var(--notice-tip-color); }
 
-.notice.warning {
-  background: var(--warning-content);
-}
-
-.notice.info .notice-title {
-  background: var(--info-title);
-}
-
-.notice.info {
-  background: var(--info-content);
-}
-
-.notice.note .notice-title {
-  background: var(--note-title);
-}
-
-.notice.note {
-  background: var(--note-content);
-}
-
-.notice.tip .notice-title {
-  background: var(--tip-title);
-}
-
-.notice.tip {
-  background: var(--tip-content);
-}
+.notice.warning { background: color-mix(in srgb, var(--notice-warning-color) var(--notice-bg-opacity), transparent); }
+.notice.info { background: color-mix(in srgb, var(--notice-info-color) var(--notice-bg-opacity), transparent); }
+.notice.note { background: color-mix(in srgb, var(--notice-note-color) var(--notice-bg-opacity), transparent); }
+.notice.tip { background: color-mix(in srgb, var(--notice-tip-color) var(--notice-bg-opacity), transparent); }
 
 .icon-notice {
   display: inline-flex;
diff --git a/static/css/palettes/runtimeterror.css b/static/css/palettes/runtimeterror.css
index 76e566e..5d6b2a9 100644
--- a/static/css/palettes/runtimeterror.css
+++ b/static/css/palettes/runtimeterror.css
@@ -2,20 +2,35 @@
  */
 
 :root {
-	--base00: #090909;  /* bg */
-	--base01: #1c1c1c;  /* off-bg */
-	--base02: #292929;  /* inner-bg */
-	--base03: #6d6c6c;  /* muted */
-	--base04: #abaaaa;  /* off-fg */
-	--base05: #d8d8d8;  /* fg */
-	--base06: #75f558;  /* code */
-	--base07: #5f8700;  /* user prompt */
-	--base08: #ab4642;  /* root prompt */
-	--base09: #dc9656;
-	--base0A: #f7ca88;  /* highlight */
-	--base0B: #682523;  /* logo */
-	--base0C: #ab2321;  /* hover */
-	--base0D: #d36060;  /* link */
-	--base0E: #ba8baf;
-	--base0F: #a16946;
+  /* dark theme colors */
+  --dark-base00: #090909;  /* bg */
+  --dark-base01: #1c1c1c;  /* off-bg */
+  --dark-base02: #292929;  /* inner-bg */
+  --dark-base03: #6d6c6c;  /* muted */
+  --dark-base04: #abaaaa;  /* off-fg */
+  --dark-base05: #d8d8d8;  /* fg */
+  --dark-base06: #75f558;  /* code */
+  --dark-base07: #5f8700;  /* user prompt */
+  --dark-base08: #ab4642;  /* root prompt */
+  --dark-base09: #abaaaa;  /* logo text */
+  --dark-base0A: #f7ca88;  /* highlight */
+  --dark-base0B: #682523;  /* logo */
+  --dark-base0C: #ab2321;  /* hover */
+  --dark-base0D: #d36060;  /* link */
+
+  /* light theme colors */
+  --light-base00: #ffffff;  /* bg */
+  --light-base01: #f0f0f0;  /* off-bg */
+  --light-base02: #dbdbdb;  /* inner-bg */
+  --light-base03: #909090;  /* muted */
+  --light-base04: #707070;  /* off-fg */
+  --light-base05: #303030;  /* fg */
+  --light-base06: #2a8f1f;  /* code */
+  --light-base07: #3f5900;  /* user prompt */
+  --light-base08: #c23d3d;  /* root prompt */
+  --light-base09: #f0f0f0;  /* logo-text */
+  --light-base0A: #d4a960;  /* highlight */
+  --light-base0B: #af3a37;  /* logo */
+  --light-base0C: #c62a28;  /* hover */
+  --light-base0D: #a04545;  /* link */
 }
diff --git a/torchlight.config.js b/torchlight.config.js
index bc799f9..8c44c81 100644
--- a/torchlight.config.js
+++ b/torchlight.config.js
@@ -11,7 +11,7 @@ module.exports = {
 
   // Which theme you want to use. You can find all of the themes at
   // https://torchlight.dev/docs/themes.
-  theme: 'synthwave-84',
+  theme: 'material-theme-lighter',
 
   // The Host of the API.
   host: 'https://api.torchlight.dev',