diff --git a/TODO b/TODO
index b573592..4ea3440 100644
--- a/TODO
+++ b/TODO
@@ -8,3 +8,4 @@
 [x] Reading time
 [x] Bio component
 [x] Add social image
+[ ] Add hero image to one of the posts
diff --git a/public/robots.txt b/public/robots.txt
index 1f53798..c2a49f4 100644
--- a/public/robots.txt
+++ b/public/robots.txt
@@ -1,2 +1,2 @@
 User-agent: *
-Disallow: /
+Allow: /
diff --git a/src/components/BaseHead.astro b/src/components/BaseHead.astro
index 7f7807b..7ff1b59 100644
--- a/src/components/BaseHead.astro
+++ b/src/components/BaseHead.astro
@@ -41,3 +41,14 @@ const socialUrl = Astro.site.href + 'assets/social.png'
 <!-- Styles -->
 <link rel="stylesheet" href={Astro.resolve('../styles/global.css')} />
 <link rel="stylesheet" href={Astro.resolve('../styles/highlight.css')} />
+
+<!-- This is intentionally inlined to avoid FOUC -->
+<script>
+  const root = document.documentElement;
+  const theme = localStorage.getItem('theme');
+  if (theme === 'dark' || (!theme) && window.matchMedia('(prefers-color-scheme: dark)').matches) {
+    root.classList.add('theme-dark');
+  } else {
+    root.classList.remove('theme-dark');
+  }
+</script>
diff --git a/src/components/Footer.astro b/src/components/Footer.astro
index e6d0b08..f8dedf1 100644
--- a/src/components/Footer.astro
+++ b/src/components/Footer.astro
@@ -1,14 +1,14 @@
 <footer>
   <span>
     &copy; {new Date().getFullYear()} Your Blog.
-    Powered by <a href="https://astro.build" target="_blank">Astro</a>.
-    Template by <a href="https://www.twitter.com/Charca" target="_blank">Maxi Ferreira</a>.
+    Powered by <a href="https://astro.build" target="_blank" rel="noopener">Astro</a>.
+    Template by <a href="https://www.twitter.com/Charca" target="_blank" rel="noopener">Maxi Ferreira</a>.
   </span>
 </footer>
 
 <style>
   footer {
-    color: #AAA;
+    color: var(--text-secondary);
     font-size: 1em;
     font-family: var(--font-family-sans);
     margin: 1em auto;
diff --git a/src/components/Logo.astro b/src/components/Logo.astro
index 08248f3..b065048 100644
--- a/src/components/Logo.astro
+++ b/src/components/Logo.astro
@@ -1,7 +1,7 @@
 <style>
   img {
     display: block;
-    height: 50px;
+    width: 75px;
   }
 </style>
 
diff --git a/src/components/Nav.astro b/src/components/Nav.astro
index 0de3a9e..f5091bb 100644
--- a/src/components/Nav.astro
+++ b/src/components/Nav.astro
@@ -1,4 +1,5 @@
 ---
+import ThemeToggleButton from './ThemeToggleButton.svelte';
 const { current = '' } = Astro.props;
 ---
 
@@ -34,7 +35,7 @@ const { current = '' } = Astro.props;
     bottom: 0;
     width: 100%;
     height: 2px;
-    background: #AAA;
+    background: var(--text-secondary);
     transform: scaleX(0);
   }
 
@@ -52,4 +53,5 @@ const { current = '' } = Astro.props;
   <a class={current === "" ? "selected" : ""} href='/'>home</a>
   <a class={current === "about" ? "selected" : ""} href='/about'>about</a>
   <a class={current === "blog" ? "selected" : ""} href='/blog'>blog</a>
+  <ThemeToggleButton client:load />
 </nav>
diff --git a/src/components/ThemeToggleButton.svelte b/src/components/ThemeToggleButton.svelte
new file mode 100644
index 0000000..a15dd2c
--- /dev/null
+++ b/src/components/ThemeToggleButton.svelte
@@ -0,0 +1,65 @@
+<script>
+  const rootEl = typeof document !== 'undefined' ? document.documentElement : null;
+  const themes = ['light', 'dark'];
+  let theme = ''
+
+  if (typeof localStorage !== 'undefined' && localStorage.getItem('theme')) {
+    theme = localStorage.getItem('theme');
+  } else if (typeof window !== 'undefined' && window.matchMedia('(prefers-color-scheme: dark)').matches) {
+    theme = 'dark';
+  }
+
+  function handleChange(event) {
+    theme = event.target.value;
+    localStorage.setItem('theme', theme);
+  }
+
+  $: if (rootEl && theme === 'light') {
+    rootEl.classList.remove('theme-dark');
+  } else if (rootEl && theme === 'dark') {
+    rootEl.classList.add('theme-dark');
+  }
+
+  const icons = [
+    `<svg
+      xmlns="http://www.w3.org/2000/svg"
+      width="20"
+      height="20"
+      viewBox="0 0 20 20"
+      fill="currentColor"
+    >
+      <path
+        fill-rule="evenodd"
+        d="M10 2a1 1 0 011 1v1a1 1 0 11-2 0V3a1 1 0 011-1zm4 8a4 4 0 11-8 0 4 4 0 018 0zm-.464 4.95l.707.707a1 1 0 001.414-1.414l-.707-.707a1 1 0 00-1.414 1.414zm2.12-10.607a1 1 0 010 1.414l-.706.707a1 1 0 11-1.414-1.414l.707-.707a1 1 0 011.414 0zM17 11a1 1 0 100-2h-1a1 1 0 100 2h1zm-7 4a1 1 0 011 1v1a1 1 0 11-2 0v-1a1 1 0 011-1zM5.05 6.464A1 1 0 106.465 5.05l-.708-.707a1 1 0 00-1.414 1.414l.707.707zm1.414 8.486l-.707.707a1 1 0 01-1.414-1.414l.707-.707a1 1 0 011.414 1.414zM4 11a1 1 0 100-2H3a1 1 0 000 2h1z"
+        clip-rule="evenodd"
+      />
+    </svg>`,
+    `<svg
+      xmlns="http://www.w3.org/2000/svg"
+      width="20"
+      height="20"
+      viewBox="0 0 20 20"
+      fill="currentColor"
+    >
+      <path d="M17.293 13.293A8 8 0 016.707 2.707a8.001 8.001 0 1010.586 10.586z" />
+    </svg>`,
+  ];
+</script>
+
+
+<div class="theme-toggle">
+  {#each themes as t, i}
+    <label class={theme === t ? 'checked' : ''}>
+      {@html icons[i]}
+      <input
+        type="radio"
+        name="theme-toggle"
+        checked={theme === t}
+        value={t}
+        title={`Use ${t} theme`}
+        aria-label={`Use ${t} theme`}
+        on:change={handleChange}
+      />
+    </label>
+  {/each}
+</div>
diff --git a/src/pages/about.astro b/src/pages/about.astro
index 63d4d75..4ce50b5 100644
--- a/src/pages/about.astro
+++ b/src/pages/about.astro
@@ -12,7 +12,10 @@ const permalink = `${Astro.site.href}about`;
     <figure>
       <img src="/assets/about-illustration.webp" alt="Illustration of a notebook">
       <figcaption>
-        Illustration by <a href="https://icons8.com/illustrations/author/5c07e68d82bcbc0092519bb6">Icons 8</a> from <a href="https://icons8.com/illustrations">Ouch!</a>
+        Illustration by
+        <a href="https://icons8.com/illustrations/author/5c07e68d82bcbc0092519bb6" target="_blank" rel="noopener">Icons 8</a>
+        from
+        <a href="https://icons8.com/illustrations" target="_blank" rel="noopener">Ouch!</a>
       </figcaption>
     </figure>
     <p>Text placeholder via <a href="https://jeffsum.com/" target="_blank">Jeffsum</a>.</p>
diff --git a/src/pages/blog/[slug].astro b/src/pages/blog/[slug].astro
index 4603536..1a025fc 100644
--- a/src/pages/blog/[slug].astro
+++ b/src/pages/blog/[slug].astro
@@ -41,7 +41,7 @@ const permalink = `${Astro.site.href}${slug}`;
   }
 
   header p {
-    color: #AAA;
+    color: var(--text-secondary);
     text-transform: uppercase;
     font-family: var(--font-family-sans);
     font-weight: 600;
diff --git a/src/pages/blog/index.astro b/src/pages/blog/index.astro
index 82b9c4b..52b2e09 100644
--- a/src/pages/blog/index.astro
+++ b/src/pages/blog/index.astro
@@ -40,7 +40,7 @@ allPosts = allPosts.sort((a, b) => new Date(b.publishDate).valueOf() - new Date(
   }
 
   .post-item-date {
-    color: #AAA;
+    color: var(--text-secondary);
     text-align: left;
     text-transform: uppercase;
     margin-right: 16px;
diff --git a/src/pages/index.astro b/src/pages/index.astro
index de4744e..4f98668 100644
--- a/src/pages/index.astro
+++ b/src/pages/index.astro
@@ -10,13 +10,16 @@ const permalink = Astro.site.href;
   <div class="home-container">
     <div class="home-copy">
       <h1>Welcome to your new Astro Blog</h1>
-      <p>Check out the docs on <a href="https://www.github.com/Charca/astro-blog-template" target="_blank">GitHub</a> to get started.</p>
+      <p>Check out the docs on <a href="https://www.github.com/Charca/astro-blog-template" target="_blank" rel="noopener">GitHub</a> to get started.</p>
     </div>
 
     <figure>
       <img alt='Illustration of person reading a book' src='/assets/home-illustration.webp'>
       <figcaption>
-        Illustration by <a href="https://icons8.com/illustrations/author/5c07e68d82bcbc0092519bb6">Icons 8</a> from <a href="https://icons8.com/illustrations">Ouch!</a>
+        Illustration by
+        <a href="https://icons8.com/illustrations/author/5c07e68d82bcbc0092519bb6" target="_blank" rel="noopener">Icons 8</a>
+        from
+        <a href="https://icons8.com/illustrations" target="_blank" rel="noopener">Ouch!</a>
       </figcaption>
     </figure>
   </div>
@@ -54,11 +57,13 @@ const permalink = Astro.site.href;
   figcaption {
     font-size: .8em;
     font-style: italic;
+    text-align: left;
   }
 
   img {
     width: 100%;
     max-width: 550px;
+    margin-bottom: 1em;
   }
 
   @media (max-width: 1200px) {
diff --git a/src/styles/global.css b/src/styles/global.css
index 20fce27..3c2015c 100644
--- a/src/styles/global.css
+++ b/src/styles/global.css
@@ -1,16 +1,18 @@
 :root {
   --background-body: #fff;
   --text-main: #36393b;
+  --text-secondary: #6b6f72;
   --primary-color: #548E9B;
   --font-family-serif: Merriweather, serif;
   --font-family-sans: 'Fira Sans', sans-serif;
 }
 
-/* :root {
-  --background-body: #36393b;
+:root.theme-dark {
+  --background-body: #202122;
   --text-main: #fff;
+  --text-secondary: #ccc;
   --primary-color: #548E9B;
-} */
+}
 
 *, *:before, *:after {
   box-sizing: border-box;
@@ -189,6 +191,48 @@ td {
   margin: 1em 0;
 }
 
+.theme-toggle {
+  display: inline-flex;
+  align-items: center;
+  height: 100%;
+  padding: 0.33em 0.67em;
+  padding-top: 8px;
+  margin-left: 10px;
+  gap: 0.6em;
+  border-radius: 99em;
+  background-color: var(--theme-code-inline-bg);
+}
+
+.theme-toggle > label:focus-within {
+  outline: 2px solid transparent;
+  box-shadow: 0 0 0 0.08em var(--theme-accent), 0 0 0 0.12em white;
+}
+
+.theme-toggle > label {
+  color: var(--theme-code-inline-text);
+  position: relative;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  opacity: 0.5;
+  cursor: pointer;
+}
+
+.theme-toggle .checked {
+  color: var(--theme-accent);
+  opacity: 1;
+}
+
+input[name='theme-toggle'] {
+  position: absolute;
+  opacity: 0;
+  top: 0;
+  right: 0;
+  bottom: 0;
+  left: 0;
+  z-index: -1;
+}
+
 @media (max-width: 1020px) {
   h1 {
     font-size: 3em;