diff --git a/src/components/Header.astro b/src/components/Header.astro
index d7e2f4e..a5da95a 100644
--- a/src/components/Header.astro
+++ b/src/components/Header.astro
@@ -1,9 +1,11 @@
 ---
 import Hamburger from "./Hamburger.astro";
 import Navigation from "./Navigation.astro";
+import ThemeIcon from "./ThemeIcon.astro";
 ---
 
 <header>
   <Hamburger />
+  <ThemeIcon />
   <Navigation />
 </header>
diff --git a/src/components/ThemeIcon.astro b/src/components/ThemeIcon.astro
new file mode 100644
index 0000000..99d660e
--- /dev/null
+++ b/src/components/ThemeIcon.astro
@@ -0,0 +1,66 @@
+<button id="themeToggle">
+  <svg width="30px" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24">
+    <path
+      class="sun"
+      fill-rule="evenodd"
+      d="M12 17.5a5.5 5.5 0 1 0 0-11 5.5 5.5 0 0 0 0 11zm0 1.5a7 7 0 1 0 0-14 7 7 0 0 0 0 14zm12-7a.8.8 0 0 1-.8.8h-2.4a.8.8 0 0 1 0-1.6h2.4a.8.8 0 0 1 .8.8zM4 12a.8.8 0 0 1-.8.8H.8a.8.8 0 0 1 0-1.6h2.5a.8.8 0 0 1 .8.8zm16.5-8.5a.8.8 0 0 1 0 1l-1.8 1.8a.8.8 0 0 1-1-1l1.7-1.8a.8.8 0 0 1 1 0zM6.3 17.7a.8.8 0 0 1 0 1l-1.7 1.8a.8.8 0 1 1-1-1l1.7-1.8a.8.8 0 0 1 1 0zM12 0a.8.8 0 0 1 .8.8v2.5a.8.8 0 0 1-1.6 0V.8A.8.8 0 0 1 12 0zm0 20a.8.8 0 0 1 .8.8v2.4a.8.8 0 0 1-1.6 0v-2.4a.8.8 0 0 1 .8-.8zM3.5 3.5a.8.8 0 0 1 1 0l1.8 1.8a.8.8 0 1 1-1 1L3.5 4.6a.8.8 0 0 1 0-1zm14.2 14.2a.8.8 0 0 1 1 0l1.8 1.7a.8.8 0 0 1-1 1l-1.8-1.7a.8.8 0 0 1 0-1z"
+    ></path>
+    <path
+      class="moon"
+      fill-rule="evenodd"
+      d="M16.5 6A10.5 10.5 0 0 1 4.7 16.4 8.5 8.5 0 1 0 16.4 4.7l.1 1.3zm-1.7-2a9 9 0 0 1 .2 2 9 9 0 0 1-11 8.8 9.4 9.4 0 0 1-.8-.3c-.4 0-.8.3-.7.7a10 10 0 0 0 .3.8 10 10 0 0 0 9.2 6 10 10 0 0 0 4-19.2 9.7 9.7 0 0 0-.9-.3c-.3-.1-.7.3-.6.7a9 9 0 0 1 .3.8z"
+    ></path>
+  </svg>
+</button>
+
+<style>
+  #themeToggle {
+    border: 0;
+    background: none;
+  }
+  .sun {
+    fill: black;
+  }
+  .moon {
+    fill: transparent;
+  }
+
+  :global(.dark) .sun {
+    fill: transparent;
+  }
+  :global(.dark) .moon {
+    fill: white;
+  }
+</style>
+
+<script is:inline>
+  const theme = (() => {
+    if (typeof localStorage !== "undefined" && localStorage.getItem("theme")) {
+      return localStorage.getItem("theme") ?? "light";
+    }
+    if (window.matchMedia("(prefers-color-scheme: dark)").matches) {
+      return "dark";
+    }
+    return "light";
+  })();
+
+  if (theme === "light") {
+    document.documentElement.classList.remove("dark");
+  } else {
+    document.documentElement.classList.add("dark");
+  }
+
+  window.localStorage.setItem("theme", theme);
+
+  const handleToggleClick = () => {
+    const element = document.documentElement;
+    element.classList.toggle("dark");
+
+    const isDark = element.classList.contains("dark");
+    localStorage.setItem("theme", isDark ? "dark" : "light");
+  };
+
+  document
+    .getElementById("themeToggle")
+    ?.addEventListener("click", handleToggleClick);
+</script>
diff --git a/src/styles/global.css b/src/styles/global.css
index db67bd9..4cdba9b 100644
--- a/src/styles/global.css
+++ b/src/styles/global.css
@@ -80,3 +80,12 @@ h1 {
     display: none;
   }
 }
+
+html.dark {
+  background-color: #0d0950;
+  color: #fff;
+}
+
+.dark .nav-links a {
+  color: #fff;
+}